Optoprep Flashcards
Which area of the extrastriate cortex is involved in the perception of motion?
A. The inferotemporal cortex (IT) B. Visual area 5 (V5) C. Visual area 2 (V2) D. Visual area 4 (V4) E. Visual area 1 (V1)
B. Visual area 5 (V5)
What is the name for the phenomenon in which a flickering light that is 10 Hz is seen as brighter than a steady light (one that does not flicker) that possesses the same average luminance?
A. The Troxler effect
B. The Purkinje tree
C. The Granit-Harper law
D. The Brucke-Bartley effect
D. The Brucke-Bartley effect
Which of the following is the correct order of structures through which the pupillary fiber pathway passes?
A. Optic nerve -> optic chiasm -> brachium of the superior colliculus -> pretectal region of the midbrain -> Edinger-Westphal nucleus
B. Optic nerve-> optic chiasm -> Lateral geniculate nucleus in the thalamus-> Edinger-Westphal nucleus
C. Optic nerve -> optic chiasm -> optic tract -> Lateral geniculate nucleus in the thalamus
D. Optic nerve -> optic chiasm -> optic tract -> pretectal region of the midbrain -> Lateral geniculate nucleus in the thalamus
A. Optic nerve -> optic chiasm -> brachium of the superior colliculus -> pretectal region of the midbrain -> Edinger-Westphal nucleus
Which of the bifocal lens designs below will create the largest amount of image jump?
A. Round 28 bifocal
B. Executive bifocal
C. FT 35 bifocal
D. FT 28 bifocal
A. Round 28 bifocal
What is the relationship between the Abbe number and chromatic aberration?
A. No relationship
B. Equal
C. Inversely proportional
D. Proportional
C. Inversely proportional
What is the power of a concave mirror (in diopters) located in air with a radius of curvature of 20 cm?
A. +10.00 D
B. -5.00 D
C. -10.00 D
D. +5.00 D
A. +10.00 D
What is the front surface power of a lens in air with a refractive index of 1.50 and radius of curvature of 50 cm?
A. 1.50 D
B. 3.00 D
C. 2.00 D
D. 1.00 D
D. 1.00 D
Which organism can be contracted in a newborn via an infected mother and was previously treated prophylactically with silver nitrate?
A. Neisseria gonorrhoeae
B. Staphylococcus aureus
C. Neisseria meningiditis
D. Corynebacterium spp
A. Neisseria gonorrhoeae
Which of the following microorganisms is associated with peptic ulcer formation?
A. Vibrio cholerae
B. Clostridium tetani
C. Helicobacter pylori
D. Campylobacter spp
C. Helicobacter pylori
Which of the following genus of organisms is responsible for tuberculosis and leprosy?
A. Mycobacterium
B. Klebsiella
C. Salmonella
D. Borrelia
A. Mycobacterium
Which of the following classifications refers to an organism that can survive in an environment with or without oxygen?
A. Facultative anaerobe
B. Strict anaerobe
C. Obligate aerobe
D. Microaerophile
A. Facultative anaerobe
What type of agar is commonly used to culture fungi?
A. Cetrimide agar B. Sabouraud's agar C. Hay infusion agar D. Blood agar plate E. Thayer-Martin agar
B. Sabouraud’s agar
What term describes the phenomenon in which a bacterium directs its movement TOWARD a chemical in its environment?
A. Phagocytosis
B. Apoptosis
C. Chemotaxis
D. Transposition
C. Chemotaxis
Which patient would be considered legally blind?
A. A retinitis pigmentosa patient who has 20/20 central vision in each eye and a 30 degree in diameter visual field
B. A wet macular degeneration patient with best central acuities of 10/120 OD and 10/200 OS
C. A patient with a total retinal detachment of the right eye, no light perception and a best corrected central acuity of 8/60 due to wet macular degeneration
D. A patient with Best’s disease with best corrected central acuities measure OD 10/80 and OS 10/100
E. A myopic patient with acuities of 20/400 OD and OS uncorrected
B. A wet macular degeneration patient with best central acuities of 10/120 OD and 10/200 OS
Which of the following skin conditions is considered to be benign and has the LOWEST risk of malignancy?
A. Keratoacanthoma
B. Actinic keratosis
C. Squamous cell carcinoma
D. Basal cell carcinoma
A. Keratoacanthoma
Which of the following is the correct pathway for the drainage of tears through the nasolacrimal drainage system?
A. Nasolacrimal duct, lacrimal sac, valve of Hasner, lacrimal canaliculus, ampulla, lacrimal punctum
B. Lacrimal punctum, lacrimal canaliculus, ampulla, valve of Hasner, nasolacrimal duct, lacrimal sac
C. Lacrimal punctum, lacrimal canaliculus, ampulla, lacrimal sac, nasolacrimal duct, valve of Hasner
D. Lacrimal sac, lacrimal punctum, lacrimal canaliculus, ampulla, nasolacrimal duct, valve of Hasner
C. Lacrimal punctum, lacrimal canaliculus, ampulla, lacrimal sac, nasolacrimal duct, valve of Hasner
You are measuring the palpebral fissure height in a patient reporting drooping of his upper eyelid. Which of the following BEST describes the normal positioning of the upper and lower eyelids in comparison to the limbus?
A. The upper lid normally rests about 2mm lower than the upper limbus, and the lower lid rests about 1mm above the lower limbus
B. The upper lid normally rests about 1mm lower than the upper limbus, and the lower lid rests about 2mm lower than the lower limbus
C. The upper lid normally rests about 1mm lower than the upper limbus, and the lower lid rests about 2mm above the lower limbus
D. The upper lid normally rests about 2mm lower than the upper limbus, and the lower lid rests about 1mm lower than the lower limbus
A. The upper lid normally rests about 2mm lower than the upper limbus, and the lower lid rests about 1mm above the lower limbus
Which of the following types of congenital cataracts are characteristic of galactosemia?
A. Blue dot (Cerulean) opacities
B. Oil droplet opacities
C. Christmas tree cataracts
D. Sunflower cataracts
B. Oil droplet opacities
When examining a patient, a pinpoint spot of the posterior surface of the lens known as Mittendorf’s dot is seen. What is this a remnant of?
A. Pupillary membrane
B. Hyaloid artery
C. Vitreous
D. Glial tissue of the optic nerve
B. Hyaloid artery
Which of the following drugs decrease intraocular pressure by increasing uveoscleral outflow?
A- Dorzolamide B- Timolol C- Brinzolamide D- Pilocarpine E- Brimonidine
E. Brimonidine
Which type of anterior scleritis is associated with the highest risk of perforation?
A. Necrotizing
B. Scleromalacia perforans
C. Nodular
D. Diffuse
A. Necrotizing
Which of the following types of scleritis presents without ocular inflammation, has a low risk for perforation, and does not typically result in pain or decreased visual acuity?
A. Granulomatous necrotizing scleritis B. Vaso-occlusive necrotizing scleritis C. Anterior non-necrotizing diffuse scleritis D. Posterior scleritis E. Nodular scleritis F. Scleromalacia perforans
F. Scleromalacia perforans
Which of the following correctly describes the autonomic innervation of the iris muscles?
A. The iris sphincter and iris dilator are both innervated parasympathetically
B. The iris sphincter is innervated parasympathetically and the iris dilator is innervated sympathetically
C. The iris sphincter is innervated sympathetically and the iris dilator is innervated parasympathetically
D. The iris sphincter and iris dilator are both innervated sympathetically
B. The iris sphincter is innervated parasympathetically and the iris dilator is innervated sympathetically
You are fitting a toric soft contact lens to your patient’s right eye. The patient’s manifest refraction is -2.00 -1.50 X 095. You apply a -1.75 -1.25 X 085 diagnostic toric soft contact lens. It fits well, and the prism base down marking consistently locates halfway between the 6 o’clock and 7 o’clock hours. What axis should you order?
A. 70 degrees B. 95 degrees C. 100 degrees D. 80 degrees E. 110 degrees
B. 95 degrees
Which one of the following bitoric GP contact lenses would NOT induce cylinder if rotated to a misaligned position on the eye?
A. 7.58 mm / -5.37 D ——————— 8.18 mm / -0.50 D
B. All of the options listed would induce cylinder if rotated off axis
C. 7.63 mm / -1.50 D ——————— 8.11 mm / +1.12 D
D. 7.54 mm / +1.50 D ——————— 7.99 mm / +2.75 D
E. 7.46 mm / -4.25 D ——————— 8.13 mm / -1.75 D
C. 7.63 mm / -1.50 D ——————— 8.11 mm / +1.12 D
Which of the following will occur if you increase the water content of a soft contact lens?
A. The tendency of lens deposits will decrease
B. The patient will report an increase in dry eye symptoms
C. The oxygen permeability will decrease
D. The lens durability will increase
B. The patient will report an increase in dry eye symptoms
Which of the following alterations will help to loosen a tightly-fitting gas-permeable lens?
A. Steepen the peripheral curve system B. Reduce the width of the peripheral curve system C. Reduce the size of the optic zone D. Increase the overall diameter E. Steepen the base curve of the lens
C. Reduce the size of the optic zone
Which of the following ocular signs is virtually pathognomonic for trachoma caused by chlamydia?
A. Superior tarsal follicles
B. Inferior tarsal papillae
C. Tranta’s dots
D. Lymphadenopathy
A. Superior tarsal follicles
Which layer of the cornea, if penetrated, will leave a scar?
A. The tear film
B. The epithelium
C. The stroma
D. The wing cell layer
C. The stroma
What is the name of the surgical procedure in which thermal laser burns are placed in the mid-periphery of the cornea in an attempt to steepen the corneal curvature?
A. Laser-assisted in-situ keratomileusis B. Radial keratotomy C. Conductive keratoplasty D. Photorefractive keratectomy E. Limbal relaxation incisions
C. Conductive keratoplasty
What is the name of the pigmented line that represents the leading edge of a pterygium?
A. Stocker's line B. Fleischer's ring C. Krukenberg's line D. Ferry's line E. Hudson-Stahli line F. Coat's white ring
A. Stocker’s line
Which of the following is a precursor to steroid hormones such as testosterone?
A. Sphingolipids
B. Triglycerides
C. Phospholipids
E. Cholesterol
E. Cholesterol
What is the net overall moles of ATP produced by the electron transport chain (i.e. not including glycolysis)?
A. 30 moles of ATP B. 6 moles of ATP C. 2 moles of ATP D. 34 moles of ATP E. 38 moles of ATP
D. 34 moles of ATP
While performing the astigmatic clock dial, your patient reports that the clearest/blackest line is the 2-8 line while the 5-11 line is the least clear. What would be the corresponding axis of astigmatism?
A. 180 degrees
B. 150 degrees
C. 60 degrees
D. 30 degrees
C. 60 degrees
Which type of light scattering is responsible for the reddish-orange colors that are often observed during sunsets?
A. Raman scattering B. Rayleigh scattering C. Brillouin scattering D. Mie scattering E. Tyndall scattering
B. Rayleigh scattering
Which of the following BEST describes the definition of irregular astigmatism?
A. The principal meridians of the cornea are not perpendicular to each other
B. The axis of astigmatism is located along the 90 degree meridian
C. The principal meridians of the cornea are located 90 degrees apart
D. The axis of astigmatism is located along an oblique axis
A. The principal meridians of the cornea are not perpendicular to each other
What separation distance will make the combination of a +3.00 and a +10.00 thin lens afocal?
A. 2.3 cm B. 17 cm C. 43 cm D. 0.43 cm E. 1.7 cm F. 23 cm
C. 43 cm
What is the minimum thickness necessary for an antireflective coating (n=1.9) to be useful against incident light of 530 nm wavelength?
A. 139.5 nm B. 58.3 nm C. 132.5 nm D. 278.9 nm E. 69.7 nm
E. 69.7 nm
What is the Interval of Sturm for a spherocylindrical lens with a power of +6.00 -2.00 x 090?
A. 41.7 cm B. 16.7 cm C. 25 cm D. 8.3 cm E. 20 cm
D. 8.3 cm
What is the equivalent of a Reduced Snellen 20/50 optotype in metric notation (assuming a working distance of 40 cm)?
A. 2M
B. 0.5M
C. 0.67M
D. 1M
D. 1M
Which of the following types of refractive error would have the greatest tendency to lead to amblyopia?
A. A four-year old boy with an uncorrected refractive error of OD: +6.00 DS and OS: +1.50 DS
B. A five-year old girl with an uncorrected refractive error of OD: -3.25 DS and OS: -0.75 DS
C. A three-year old boy with an uncorrected refractive error of OD: +1.50 DS and OS: -2.00 DS
D. A four-year old girl with an uncorrected refractive error of OD: +1.00-1.50 x 180 and OS: +1.50-1.25 x 180
A. A four-year old boy with an uncorrected refractive error of OD: +6.00 DS and OS: +1.50 DS
A chin fissure is a dominant trait. If a father who is homozygous-dominant for this trait and a mother who is homozygous-recessive for this trait mate, what are the chances that their first child will have a chin fissure?
A. 100% B. 0% C. 75% D. 25% E. 50%
A. 100%
A 31-year old male patient presents to your office for a photorefractive keratectomy (PRK) pre-operative examination. As you review his required ocular medication schedule, which of the following prescribed drops must you remember to tell him to “shake well” before instillation?
A. FreshKote®
B. Acular®
C. Pred Forte®
D. Zymaxid®
C. Pred Forte®
A 24-year old female patient presents at your office complaining of side effects that began when she started using Patanol® to treat her ocular allergies. She reports complete compliance with her eye drop administration. Which of the following symptoms is MOST likely associated with olopatadine (Patanol®) use?
A. Headache B. Visual Hallucinations C. Depression D. Gastrointestinal discomfort E. Tachycardia
A. Headache
A person who is missing the photopigment chlorolabe is categorized as which of the following?
A. A deuteranomalous trichromat B. A protanomalous trichromat C. A tritanope D. A protanope E. A deuteranope
E. A deuteranope
What is the MOST common side effect associated with intravenous administration of sodium fluorescein in patients requiring a fluorescein angiography?
A. Localized tissue necrosis B. Bronchospasm C. Nausea and vomiting D. Anaphylaxis E. Elevated temper
C. Nausea and vomiting
What is the total cumulative dosage of chloroquine that is MOST commonly associated with retinal toxicity?
A. 1,000 grams B. 1500 grams C. 4,000 grams D. 300 grams E. 100 grams
D. 300 grams
Which of the following antibiotics is classified as a macrolide?
A. Tetracycline
B. Amoxicillin
C. Erythromycin
D. Tobramycin
C. Erythromycin
Which of the following BEST describes the reasoning for the need to taper topical ocular corticosteroids?
A. Minimize the risk of developing steroid-induced elevation of IOP
B. Decrease the risk of posterior subcapsular cataract formation
C. Minimize risk of adrenal insufficiency due to decreased production of natural cortisol
D. Avoid signs and symptoms of rebound ocular inflammation
E. Prevent possible secondary ocular infections
D. Avoid signs and symptoms of rebound ocular inflammation
Which of the following medications should be taken with an empty stomach?
A. Tetracycline
B. Cephalexin (Keflex®)
C. Doxycycline
D. Amoxicillin with clavulanate (Augmentin®)
Tetracycline
What substance is secreted by the alveolar epithelium to reduce the surface tension between alveoli of the lungs?
A. Intrapleural fluid
B. Surfactant
C. Angiotensin
D. Carbon dioxide
B. Surfactant
Which class of antibody crosses the blood-placenta barrier and protects newborns for the first months of life until they produce their own antibodies?
A. IgD B. IgA C. IgM D. IgE E. IgG
E. IgG
Which of the following actions does not require input from the brain and therefore is referred to as a spinal reflex?
A. Catching a ball
B. Painting a picture
C. Maintaining balance while riding a bicycle
D. Pulling your hand away from a hot stove
E. Dodging out of the way when an object is thrown in your direction
D. Pulling your hand away from a hot stove
Which of the following antibodies is the first to be secreted during an immune response?
A. IgD antibodies B. IgM antibodies C. IgE antibodies D. IgA antibodies E. IgG antibodies
B. IgM antibodies
Which of the following walls of the orbit is MOST susceptible to a blowout fracture secondary to blunt ocular trauma?
A. Medial wall
B. Floor
C. Lateral wall
D. Roof
B. Floor
Which of the primary germ layers of embryonic development take part in the development of ocular structures?
A. Ectoderm only B. Endoderm only C. Mesoderm and ectoderm D. Mesoderm and endoderm E. Ectoderm and endoderm
C. Mesoderm and ectoderm
Which two layers of the iris are derived from mesoderm?
A. The anterior limiting layer and the stroma
B. The stroma and the anterior epithelium
C. The stroma and the posterior pigmented epithelium
D. The epithelium and the posterior pigmented epithelium
E. The posterior pigmented epithelium and the anterior limiting layer
A. The anterior limiting layer and the stroma
Which of the following components of the AREDS I ocular vitamin formula used for dry age-related macular degeneration is contraindicated in smokers?
A. Copper B. Beta-carotene C. Zinc E. Vitamin C D. Vitamin E
B. Beta-carotene
Which of the following correctly lists the layers of the retina beginning with the retinal pigment epithelium and moving anteriorly?
A. Retinal pigment epithelium, outer nuclear layer, external limiting membrane, photoreceptor layer, outer plexiform layer, inner plexiform layer, inner nuclear layer, nerve fiber layer, ganglion cell layer, internal limiting membrane
B. Retinal pigment epithelium, photoreceptor layer, outer nuclear layer, external limiting membrane, outer plexiform layer, inner plexiform layer, inner nuclear layer, ganglion cell layer, nerve fiber layer, internal limiting membrane
C. Retinal pigment epithelium, photoreceptor layer, external limiting membrane, outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, ganglion cell layer, nerve fiber layer, internal limiting membrane
D. Retinal pigment epithelium, external limiting membrane, outer nuclear layer, photoreceptor layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, nerve fiber layer, ganglion cell layer, internal limiting membrane
C. Retinal pigment epithelium, photoreceptor layer, external limiting membrane, outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, ganglion cell layer, nerve fiber layer, internal limiting membrane
Which of the following structures serves as the strongest attachment point of the vitreous?
A. The ora serrata
B. Blood vessels
C. The optic nerve head
D. The macula
A. The ora serrata
Which of the following organisms can penetrate an INTACT cornea?
A. Streptococcus aureus
B. Haemophilus influenza
C. Salmonella enterica
D. Staphylococcus epidermis
B. Haemophilus influenza
What is the vergence demand using a Variable Tranaglyph when the separation is measured as 4 cm at a distance of 80 cm when training divergence?
A. 20 prism diopters base-out
B. 5 prism diopters base-in
C. 20 prism diopters base-in
D. 5 prism diopters base-out
B. 5 prism diopters base-in
When analyzing a gas-permeable lens, you measure base curves of 7.58 and 7.84 with a radiuscope, and -1.00 and -2.50 on lensometry. What type of toric gas-permeable contact lens design do you have?
A. Cylinder power effect (CPE) bitoric B. Spherical power effect (SPE) bitoric C. Thin-flex D. Back surface (base curve) toric E. Front surface (F1) toric
B. Spherical power effect (SPE) bitoric
Which of the following is the MOST common early pattern of a glaucomatous visual field defect?
A. Para-central scotoma B. Inferior arcuate C. Enlarged blind spot D. Superior nasal step E. Inferior nasal step F. Superior arcuate
A. Para-central scotoma
What portion of the progressive lens should be used to verify the distance prescription when the lenses arrive from the lab?
A. The major reference point (MRP)
B. The prism reference point (PRP)
C. The center of the fitting cross
D. The center of the distance arc
D. The center of the distance arc
Which of the following acquired color vision deficiencies would you MOST expect to see in optic nerve disease and macular disease, respectively?
A. Red-green, blue-yellow
B. Red-green, rod monochromacy
C. Blue-yellow, rod monochromacy
D. Blue-yellow, red-green
A. Red-green, blue-yellow
What is the main mechanism of action of fluticasone and salmeterol, which are components found in Advair®, respectively?
A. Bronchodilator; anti-inflammatory
B. Anti-histamine; anti-inflammatory
C. Anti-inflammatory; anti-histamine
D. Anti-inflammatory; bronchodilator
E. Anti-inflammatory; leukotriene inhibitor
F. Leukotriene inhibitor; anti-inflammatory
D. Anti-inflammatory; bronchodilator
In which of the following conditions are bandage contact lenses NOT typically utilized?
A. Eyelid entropion B. Filamentary keratitis C. Post-LASIK surgery D. Recurrent corneal erosion E. Bullous keratopathy
C. Post-LASIK surgery
Which of the following infections must be reported to the CDC (Centers for Disease Control and Prevention)?
A. Acanthamoeba
B. Herpes Simplex
C. Syphilis
D. Epidemic keratoconjunctivitis (EKC)
C. Syphilis
Which of the following systemic conditions can cause a falsely low measurement of a patient’s hemoglobin A1c level?
A. Chronic opioid use B. Alcoholism C. Hyperbilirubinemia D. Pregnancy E. Iron deficient anemia
D. Pregnancy
A father brings in his two-year old son for evaluation at your office. The father remarks that his son was born with what appears as a small red birthmark on his forehead. He wishes to know if it requires treatment or warrants removal. Applying pressure over the area of interest causes blanching of the lesion, and the father reports that the birthmark appears darker when his son cries. What is your prognosis?
A. Benign but is likely to be permanent and will darken will time
B. Malignant and requires immediate biopsy
C. Benign and will likely regress by the time the child is 5 years of age
D. A pre-cursor to a malignant condition and will continue to increase in size with time
C. Benign and will likely regress by the time the child is 5 years of age
A +3.00 D hyperope is corrected with a +1.50 D contact lens bilaterally. If he views a near object located at 22.0 cm, what degree of accommodation is required to achieve a clear retinal image (rounded to the nearest 0.25 D)?
A. +4.50 D
B. +1.50 D
C. +6.00 D
D. +7.50 D
C. +6.00 D
A 12 year-old patient is seen at your office complaining of distance blur. Cover test reveals 4 prism diopters of exophoria at near. Subjective refraction reveals -2.25 DS OU. The patient returns 4 weeks later and reports that her vision is clear at distance with the glasses, but when she reads her eyes become fatigued and she reports frontal headaches, all of which she did not experience prior to getting her glasses. What is the MOST likely etiology of her headaches while reading?
A. Resultant esophoria at near induced by her glasses
B. The pantoscopic tilt is incorrect and is inducing unwanted astigmatism
C. The optical center of her glasses was measured too low
D. Her glasses are too tight and are putting pressure on her temples
A. Resultant esophoria at near induced by her glasses
You ask your patient to place a red lens in front of their right eye and proceed to perform the red lens test. Your patient reports seeing two images with the red image being perceived to the left of the white light. What type of deviation corresponds with the above findings?
A. Esophoria
B. Exophoria or exotropia
C. Hyperphoria
D. Hypophoria
B. Exophoria or exotropia
While performing the astigmatic clock dial, your patient reports that the 1-7 and 2-8 lines are equally blacker and clearer than all of the other lines. What would be the corresponding axis of astigmatism?
A. 90 degrees
B. 45 degrees
C. 30 degrees
D. 60 degrees
B. 45 degrees
Myasthenia gravis is an autoimmune disease that affects which of the following types of receptors in the body?
A. Beta-adrenergic receptors B. Muscarinic acetylcholine receptors C. Nicotinic acetylcholine receptors D. Alpha-adrenergic E. Adenosine receptors
C. Nicotinic acetylcholine receptors
You suspect allergic conjunctivitis as the cause of your 22 year-old patient’s symptoms of red, watery, itchy eyes. If you were to perform a conjunctival scraping, the presence of which of the following types of cells would confirm your diagnosis?
A. Monocytes B. Basophils C. Neutrophils D. Eosinophils E. Lymphocytes
D. Eosinophils
What is the mean horizontal and vertical diameter of the human cornea, respectively (when viewed ANTERIORLY)? A. 11.7mm, 10.6mm B. 10.6mm, 11.7mm C. 10.2mm, 11.5mm D. 11.5mm, 10.2mm
A. 11.7mm, 10.6mm
You suspect allergic conjunctivitis as the cause of your 22 year-old patient’s symptoms of red, watery, itchy eyes. If you were to perform a conjunctival scraping, the presence of which of the following types of cells would confirm your diagnosis?
A. Monocytes B. Basophils C. Neutrophils D. Eosinophils E. Lymphocytes
D. Eosinophils
Your last patient of the day insists on being fit with a soft toric contact lens. Her subjective refraction is -3.00 -2.50 x 178. Which of the following lenses would be the BEST choice to use as a trial lens for her fitting evaluation?
A. -3.00 -0.75 x 180 B. -2.75 -2.25 x 140 C. -2.75 -1.75 x 090 D. -1.00 -2.25 x 180 E. +2.00 -2.25 x 180
A. -3.00 -0.75 x 180
The blood-aqueous barrier is formed by tight junctions between which cells of the ciliary body?
A. The non-pigmented epithelial cells B. The pigmented epithelial cells C. The stromal cells D. Basal laminar cells E. The circular cells
A. The non-pigmented epithelial cells
The lens changes significantly as we age. One of these changes is the formation of vacuoles. What causes this?
A. Loss of lenticular capsule elasticity causing decreased accommodation
B. Glutathione loss with age causing cross linking between proteins
C. Decreased function of the sodium/potassium pump causing decreased protein synthesis
D. The separation of water from proteins causing agglutination of proteins and pooling of water
D. The separation of water from proteins causing agglutination of proteins and pooling of water
The presence of foam at the canthus is thought to be pathognomonic for blepharitis. What is the direct etiology of the foam?
A. A detergent effect from altered meibomian gland lipids
B. Tear film debris such as sloughed epithelial cellular material that is increased in dry eye
C. Increased lysozymes react with free radicals to produce a froth-like material
D. Mucin balls form from increased ocular surface shear forces exerted by the eyelids in dry eye
E. Bacterial lipases resulting from low-grade infection within the meibomian glands
A. A detergent effect from altered meibomian gland lipids
A patient is seen at your office complaining of distance blur with his glasses. With his current prescription of -1.25 D in place, you determine that his far point is 50 cm from the spectacle plane for his left eye. Given this information, which of the following is the MOST appropriate spectacle prescription to obtain a clear retinal image when an object is viewed at optical infinity (rounded to the nearest 0.25 D)?
A. +0.75 D B. -2.00 D C. -0.75 D D. -1.25 D E. -3.25 D
E. -3.25 D
How much image jump will be created by a +2.00 D flat top 25 mm segment add with a carrier lens of +2.25 DS?
A. 1.125 prism diopters B. 1 prism diopter C. 2.125 prism diopters D. 5.31 prism diopters E. 2.5 prism diopters
B. 1 prism diopter
Hutchinson’s sign associated with herpes zoster is an indication of reactivation of which of the following cranial nerves?
A. Nasociliary branch of the trigeminal nerve
B. Lacrimal branch of the trigeminal nerve
C. Facial nerve
D. Frontal branch of the trigeminal nerve
A. Nasociliary branch of the trigeminal nerve
Cyclosporine is commonly used topically to treat certain eye conditions including keratoconjunctivitis sicca (KCS). Which of the following is a known mechanism of action for cyclosporine?
A. Inhibition of T-cell activation
B. Stabilization of mast cells
C. Inhibition of cyclooxygenase (COX)
D. Antagonism of vitamin K
A. Inhibition of T-cell activation
In order to maximize drug penetration through the cornea an ophthalmic drug or its vehicle should possess which property?
A. High alcohol content
B. Highly polar component
C. High pH
D. Lipid solubility
D. Lipid solubility
Explanation - Ophthalmic drops that are comprised of both lipid (non-polar) and water-soluble (polar) components result in the most effective preparation. The tight junctions of the corneal epithelium keep hydrophilic drugs out but allow good penetration for lipid-soluble drugs. In contrast, the corneal stroma demonstrates good penetration for water-soluble agents. However, a HIGHLY polar agent will not cross the corneal epithelium; therefore, a mildly polar substance is advantageous over a highly polar agent. One should NEVER place alcohol on the eye as it will instantly debride the corneal epithelium; ALWAYS rinse all instruments used for ocular procedures with saline solution after sterilization with any agent that could be toxic to the cornea. Solutions with high pH (basic) are more damaging to the cornea than solutions with a lower pH (acidic). It is important to use solutions that are close to a neutral pH (7.0) to eliminate possible damage to the cornea.
A 66 year-old male presents with a facial nerve palsy resulting in weakness of both the upper and lower portions of the right side of his face. Which of the following BEST describes the characteristics of the involved motor neuron?
A. Right lower motor neuron
B. Left lower motor neuron
C. Left upper motor neuron
D. Right upper motor neuron
A. Right lower motor neuron
Explanation - A unilateral lesion to a lower motor neuron of the facial nerve will result in weakness of upper and lower portions of the face on the ipsilateral side of the lesion. Therefore, in this case, because the upper and lower portions of the right side of the face are affected, the involved motor neuron would be a right lower motor neuron.
The branch of the facial nerve that serves the upper portion of the face receives innervation from both the right and left corticobulbar tracts, while the branch of the facial nerve that serves the lower portion of the face only receives innervation from the contralateral side of the brain. If a lower motor neuron lesion occurs, both of these branches are affected, and all muscles of facial expressions beyond that point on the ipsilateral side of the face will experience weakness.
Central serous retinopathy (CSR) is associated with an acute decrease in vision along with central distortion. The condition usually occurs unilaterally. Which gender and age group tends to have the highest incidence of CSR?
A. Males; ages 50-70
B. Males; ages 30-50
C. Females; ages 20-40
D. Females; ages 10-20
B. Males; ages 30-50
This condition causes fluid to leak from the choriocapillaries into the subretinal area, causing a serous detachment of the neurosensory retina. There is an associated loss of the foveal reflex, a hyperopic shift, a potential relative scotoma, and metamorphopsia. Flourescein angiography will reveal hyperfluorescence that appears like a smoke-stack. Evaluation of the posterior pole will typically display a blister-like elevation of the neurosensory retina. The patient is monitored monthly and intervention is rarely required, as most cases of CSR will resolve within roughly 6 months.
Which of the following wavelengths of visible light has an increased association with the development of macular degeneration?
A. 415nm-455nm
B. 520nm-555nm
C. 485nm-510nm
D. 570nm-620nm
A. 415nm-455nm
Explanation - Recent studies have demonstrated a correlation between blue-violet light that lies within the range of 415nm-455nm and the development of macular degeneration. Excessive exposure to light that falls within this bandwidth is associated with death of the retinal pigment epithelial cells. However, blue-turquoise light (465-495nm) does not appear to possess detrimental effects to ocular health. Blue-turquoise light is important in activation of the pupillary reflex as well as management of the circadian sleep/wake cycle. There is increasing evidence that compact fluorescent lamps, LED lights as well as sunlight all transmit blue-violet light, which over time may be linked with retinal damage
A 24-year old female wears soft contact lenses with a Dk/t of 175 and admits to sleeping in her lenses. She is very satisfied with both the comfort and the vision of her lenses. Biomicroscopy reveals mucin balls under her lenses bilaterally that leave impressions in her central corneas upon removal of her lenses. Which of the following actions would BEST help to eliminate the formation of mucin balls?
A. Maintaining the same lens material but changing to a steeper base curve
B. Changing her multi-purpose solution
C. Altering the power of the contact lens but maintaining the same lens material
D. Instructing the patient to increase her blinking frequency
A. Maintaining the same lens material but changing to a steeper base curve
Explanation - Mucin balls appear as small, white, pearl-like debris that occur behind the posterior surface of contact lenses. They generally occur with silicone hydrogel lenses that are fit too flat and are used for extended wear purposes. Mucin balls do not actually pose a threat to vision and do not generally compromise the integrity of the cornea. However, if they are severe enough, there are several options available to clinicians to combat their formation. An easy way to decrease generation of mucin balls is to steepen the base curve of the lens. Alternatively, one can decrease the amount of extended wear or add re-wetting drops to the patient’s contact lens regimen. Upon removal, mucin balls will cause pooling of sodium fluorescein but will not cause staining of the cornea.
A 23-year old female is seen at your office with concerns of eye fatigue, diplopia and headaches after 30 minutes of computer use. Her subjective refraction is +0.25 D OU. Her near point of convergence is 15 centimeters. What is the most likely diagnosis based solely upon this information?
A. Brain tumor
B. Convergence excess
C. Latent hyperopia
D. Convergence insufficiency
D. Convergence insufficiency
Explanation - The most notable of the exam findings is the near point of convergence (NPC) -generally one expects an NPC of less than 6cm (closer is better with NPC). Her NPC is receded to 15 cm. Normally, if patients display a receded NPC but they are asymptomatic, no treatment is necessary. In the above case, the patient is experiencing diplopia and asthenopia with prolonged near work which infers some type of intervention may be required (likely vision therapy). Brain tumors typically present as headaches that are present in the morning and worsen over a time period of weeks to months. Latent hyperopia normally presents as blurry vision and headaches with prolonged near work, but diplopia is generally absent.
A 47-year old man sustained orbital trauma and now presents with complaints of retro-orbital pain, impaired ability to move the eye, a droopy eyelid, and diplopia. These signs are most consistent with damage to which of the following structures?
A. Internal auditory meatus
B. Superficial temporal artery
C. Superior orbital fissure
D. Stylomastoid foramen
C. Superior orbital fissure
A 6-year old white male presents with a mild left head turn. Wet retinoscopy reveals OD: +0.25 OS: +0.50 with best corrected acuities of 20/20 in each eye. Extraocular movements show limited adduction of the left eye in right gaze. It is also noted that the left eye retracts with a narrowing of the eyelid fissure. What is the most appropriate diagnosis for this patient?
A. Brown syndrome OS B. Duane Syndrome Type II OD C. Bilateral Brown Syndrome D. Duane Syndrome Type II OS E. Duane Syndrome Type III OS F. Duane Syndrome Type I OS
D. Duane Syndrome Type II OS
Explanation - Limited adduction to an affected eye usually points to a lateral rectus problem. In this case, Duane Syndrome is suspected due to the additional sign of eye retraction and narrowing of the eyelid fissure. Duane Syndrome Type III is the most appropriate diagnosis due to the limited ADDuction of the affected eye on right gaze, along with the left head tilt, which also implies limited ABDuction as well.
Duane Syndrome Type I describes limited ABDuction of the affected eye (the most common) as well as a possible compensatory head tilt toward the involved side.
Duane Syndrome Type II describes limited ADDuction of the affected eye, as well as a possible compensatory head tilt toward the uninvolved side.
Duane Syndrome Type III describes limited ABDuction AND limited ADDuction of the affected eye. It also usually presents with a compensatory head tilt toward the involved side.
A good way to remember the difference between the three types is that type I results in an aBDuction deficit (aBDuction has one D therefore it is type I).
Type II causes an aDDuction deficit (aDDuction has two Ds therefore it is type II). Type III has three Ds, aBDuction and aDDuction-the number of the types matches the number of Ds in the deficit.
Brown syndrome describes a limitation of elevation in adduction. It is a limitation of the superior oblique tendon.
A patient with a high AC/A ratio (8/1) displays esophoria at a 6 m distance. Based on the AC/A ratio, how would you expect the phoria to change as the target is brought closer to the patient?
A. Increase in eso deviation
B. Increase in exo deviation
C. Decrease in eso deviation
D. Remain unchanged
A. Increase in eso deviation
Explanation - The AC/A ratio denotes the amount of change to convergence resulting from a change in accommodation. If a patient possesses a high AC/A ratio (6/1 is considered the normal range), a one-diopter increase in accommodation will theoretically cause a greater increase in convergence. Regardless of the initial phoria, with decreasing viewing distance the phoria will become more eso (or less exo). The opposite holds true for a low AC/A ratio (less than 6/1); as the target gets closer, the resultant phoria becomes more exo or less eso.
As the interpupillary distance increases what happens to the amount of convergence (in prism diopters) needed to maintain fusion for a near target ?
A. It increases, but only for targets closer than 4 cm
B. It increases
C. It remains the same
D. In decreases, but only for targets closer than 4 cm
E. It decreases
B. It increases
Explanation - There is a direct correlation between the amount of convergence necessary to maintain fusion on a near target and interpupillary distance (IPD). As the IPD increases, so does the amount of convergence required to maintain fusion. Logically, this makes sense: if the eyes are further apart then they must rotate to a greater degree around the horizontal axis to maintain fusion if the target distance remains the same.
A concerned father reports that one of his 12-month-old infant’s eyes does not appear straight. You decide to perform the Hirschberg test to evaluate for strabismus. The corneal reflex of the right eye is centered, while the left reflex is displaced 0.5 mm superiorly relative to the center of the pupil. Angle Kappa (Lambda) is zero for each eye. What is the correct deviation and magnitude of the observed strabismus?
A. Left hypertropia of 11 prism diopters
B. Left hypertropia of 22 prism diopters
C. Left hypotropia of 11 prism diopters
D. Left hypotropia of 22 prism diopters
C. Left hypotropia of 11 prism diopters
Explanation - The Hirshberg test is performed at a distance of 50 cm. A penlight or transilluminator is held just below the doctor’s preferred eye and the doctor then sits in front of the patient and directs the beam towards the patient’s nose while the patient is instructed to fixate on the light. The position of the corneal reflexes relative to the center of the pupil is assessed in each eye. Superior displacement of the corneal reflex suggests hypotropia, while inferior displacement infers hypertropia. Each millimeter of displacement of the reflex from the center of the pupil equates to roughly 22 prism diopters of deviation.
In order to determine if environmental elements aid in the development of ametropia, researchers reared an infant monkey with a clear lens placed over one eye. These studies determined that putting a minus lens over one eye induced which type of refractive error?
A. Large amounts of astigmatism
B. Myopia
C. Presbyopia
D. Hyperopia
B. Myopia
Explanation - Although there has been much debate in the past over whether or not the etiology of refractive errors was environmental versus inherited, it is now believed that both factors contribute to the development of ametropias. Hung et al, 1995 demonstrated that by placing a prescription lens over one eye of an infant monkey and removing it after the eye had reached maturity, the mature eye developed the refractive error that the lens is normally meant to neutralize. A minus lens induced myopia and a plus lens induced hyperopia. Regardless of whether the etiology of the refractive error is inherited or environmental, it is absolutely essential that a clear retinal image be present in order for emmetropization to occur.
A young strabismic child presents at your office. Using visuoscopy you ask the patient to fixate the center of the target with their right eye (the left eye is occluded). The foveal reflex is positioned three hash marks to the LEFT of the center of the target. This finding suggests which type of fixation? (assume each hash mark is equal to 1 prism diopter)
A. 3 prism diopters superior eccentric fixation
B. 3 prism diopters inferior eccentric fixation
C. 3 prism diopters nasal eccentric fixation
D. The patient does not possess any eccentric fixation
E. 3 prism diopters temporal eccentric fixation
C. 3 prism diopters nasal eccentric fixation
Explanation - Visuoscopy is an excellent technique to evaluate for eccentric fixation. This is performed by using the cross-hair target of your direct ophthalmoscope and projecting it onto the macula of the unoccluded eye. The patient is asked to fixate on the center of the target. No eccentric fixation is present if the foveal reflex aligns with the center of the cross-hairs. If the foveal reflex is to the left of the center (for the right eye), then the patient has nasal eccentric fixation. If the foveal reflex is located to the right of the target center, the patient possesses temporal eccentric fixation. The opposite holds true for the left eye (if the foveal reflex is to the right of the target center, the patient has nasal eccentric fixation). If the foveal reflex is located above the target, then the patient has inferior eccentric fixation, whereas a foveal reflex below the target is classified as superior eccentric fixation.
In order to calculate the amount of eccentric fixation, you will have to know that from the center of the circle on the visuoscopy target to the edge of the circle is one prism diopter, and then each hash mark away from the center circle is an additional prism diopter. Therefore, the above patient has a total of 4 prism diopters of eccentric fixation (1 to the edge of the circle, and 3 for each additional hash mark).
A convex crown glass lens in air has a radius of curvature of 4 cm. What is the dioptric power of the lens?
A. -4 diopters B. -13 diopters C. +13.0 diopters D. -8.25 diopters E. +8.25 diopters F. +4 diopters
C. +13.0 diopters
Explanation - The equation for the power of a curved surface is:
D= (n’-n/r)
D= power of the lens (may also be notated as F or P)
n’= 2nd index (image), n= 1st index (object)
r= radius of curvature (in meters)
D= (1.52-1.0)/ 0.04 D= (+)13.0 diopters
Remember that converging (or convex) surfaces will have positive power, and diverging (or concave) surfaces will have negative power. If this question was changed to a concave glass lens, the radius of curvature would be negative; therefore, the power of the lens would be (-) 13 diopters.
A cornea that displays toricity is said to have with-the-rule astigmatism if it possesses which of the following keratometry readings?
A. The vertical meridian is flatter than the other principal meridian
B. The horizontal meridian has a shorter radius of curvature
C. The horizontal meridian is steeper than the other principal meridian
D. The vertical meridian is steeper than the other principal meridian
D. The vertical meridian is steeper than the other principal meridian
Explanation - With-the-rule astigmatism occurs when the vertical meridian is steeper than the other principal meridian; that is, the horizontal meridian is flatter and corresponds with the axis of the astigmatism. In this case, the vertical meridian would have a shorter radius of curvature indicating that it possesses a greater dioptric power than the horizontal meridian. If the steeper meridian lies between 60 and 120 degrees, the cornea is said to have with-the-rule astigmatism. If the steeper meridian lies between 150 and 30 degrees, the cornea displays against-the-rule astigmatism. Anything outside of these meridians is considered oblique astigmatism.
A lens system in air consists of a +4.00 diopter and +6.00 diopter lens separated by 10 cm. What is the equivalent power of this optical system?
A. +12.4 diopters B. +9.76 diopters C. +7.6 diopters D. +10.0 diopters E. +10.24 dioptersC
C. +7.6 diopters
Explanation - De = D1 + D2 - (t/n) x D1D2
De = equivalent power, D1 = front surface power, D2 = back surface power
t = thickness of lens system, n = index between the 2 surfaces
In the above question, t = 10 cm (0.1 m), n=1.0, D1 = +4.00 and D2 = +6.00
De = 4 + 6 - ((0.1/1.0) x (4) x (6)) De = 10 - (0.1 x 4 x 6) De = 10 - (2.4) De = +7.6 diopters
A patient views a bichrome visual acuity chart with no lenses before his eyes. With the patient’s left eye occluded, he reports that the letters on the red side of the chart appear blacker and darker. With his right eye occluded, the letters on the green side appear blacker and darker. Given these observations and assuming that accommodation is at rest, what would likely be the refractive condition of the right eye and left eye respectively?
A. Hyperopia and myopia B. Myopia and myopia C. Myopia and hyperopia D. Hyperopia and emmetropia F. Myopia and emmetropia E. Emmetropia and hyperopia
C. Myopia and hyperopia
Explanation - For an emmetropic eye that is not accommodating, the chromatic interval within the eye would be positioned so that the anterior (green) and posterior (red) ends of the interval are equidistance from the retina (i.e. the midpoint of the interval would be at the retina) and thus the letters on the red and green sides of the chart would appear equally black and dark. For uncorrected myopia, the interval would shift forward and thus the red end of the interval moves closer to the retina. In this case, the letters on the red side would appear blacker and darker. For uncorrected hyperopia, the interval would shift backward and thus the green end of the interval moves closer to the retina. In this case, the letters on the green side would appear blacker and darker.
Any optical system in air has first and second nodal points that coincide with which of the following corresponding points?
A. Front and back surfaces of the optical system
B. The geometrical center of the optical system
C. First and second focal points
D. First and second principal points
D. First and second principal points
Explanation - The first and second nodal points (N and N’) of an optical system are unique conjugate points such that an incident ray directed at N yields a final ray emerging from N’ that is undeviated and parallel to the initial ray.
For any optical system in air, the first and second nodal points (N and N’) correspond to the first and second principal points (P and P’).
How does uncorrected myopia affect a near phoria?
A. It results in greater hypophoria
B. It results in greater hyperphoria
C. It results in greater esophoria or less exophoria
D. It will not change the degree of phoria
E. It results in greater exophoria or less esophoria
E. It results in greater exophoria or less esophoria
Explanation - If myopia is not corrected the stimulus for accommodation is decreased resulting in less “accommodative” convergence; this will likely lead to less esophoria, or more exophoria. The opposite is true for an uncorrected hyperope. Uncorrected hyperopia will cause an increased accommodative convergence response leading to greater convergence and therefore less exophoria or more esophoria
If a thin lens with an index of 1.5 has a dioptric power of +4.00 in air, what is its power if placed in water?
A. +11.76 diopters
B. +4.00 diopters
C. +1.36 diopters
D. +1.18 diopters
C. +1.36 diopters
Explanation - D (air) / D (water) = n (lens) - n (air) / n (lens) - n (water)
+4.00 / D (water) = 1.5 - 1.0 / 1.5 - 1.33
D (water) = +1.36 diopters
Alpha helices and beta sheets are considered which level of protein structure?
A. Quaternary
B. Primary
C. Tertiary
D. Secondary
D. Secondary
An amphipathic molecule will react in what manner when exposed to water?
A. It will completely dissolve
B. It will form micelles
C. It will form a gas
D. It will combust
B. It will form micelles
Explanation - Amphipathic molecules, such as phosphatidylcholine, contain both polar and non-polar components. Because water is polar, it will dissolve other polar compounds (like dissolves like). Upon exposure to water, the hydrophilic polar elements of the amphipathic molecule will begin to align and point outwards towards the water, eventually forming small spheres called micelles. The inner portion of the micelle is comprised of the non-polar elements which are hydrophobic. Micelle formation increases the entropy of water molecules; therefore, the water molecules are less ordered; this is a more favorable outcome. If the solvent is non-polar, then an inverse micelle will form, with the hydrophobic portions pointing outwards. Entropy is a measure of disorder; higher entropy entails less order. Lipid bilayers are formed based on the principals of micelle formation.
Coenzyme Q, vitamins A, D, E, and K, and cholesterol are all derived from which of the following lipids?
A. Isoprenes and terpenes
B. Sphingolipids
C. Phospholipids
D.Triglycerides
A. Isoprenes and terpenes
Explanation
Coenzyme Q, all steroids, cholesterol, and vitamins A, D, E, and K are derived from isoprenes or terpenes. These agents contain or at some point originated from precursors that were comprised of isoprene units. Isoprene units have the chemical formula C5H8.
Sphingolipids are important in cell membranes, especially those located in the central nervous system such as myelin sheath. Shingolipids contain shingosine as a backbone and are then further classified depending upon which molecules are attached to that backbone, such are ceremides, gangliosides, sphingomyelin, etc.
Phospholipids contain a polar and non-polar end, thus making them amphoteric. This property allows for the formation of bilayers (polar ends aligned together and pointed outwards) resulting in the lipid bilayer commonly seen in cell membranes. Phospholipids are generally comprised of a phosphate group, a choline group (polar), and two fatty acid chains (non-polar) attached to glycerol, which serves as the backbone.
Triglycerides are comprised of three fatty acid chains attached to a glycerol backbone. Triglycerides are important in long-term energy storage for use by cells.
Dietary triglycerides are metabolized primarily by which organ of the body?
A. Stomach
B. Liver and gall bladder
C. Intestine
D. Kidney
C. Intestine
Explanation
Fat is digested primary in the intestine. It enters the intestine from the stomach, where it becomes emulsified by bile salts and hydrolyzed by lipases released from the pancreas. These end products are then absorbed by enterocytes that line the walls of the intestine. Once in the enterocytes, triglycerides are then rebuilt and packaged along with cholesterol and protein to form chylomicrons. The chylomicrons are able to enter the lymph system, where they are absorbed into the blood stream and transported to the liver or adipose tissue. Triglycerides cannot directly diffuse through the cell membranes of the liver or adipose tissue; they must first be broken down into fatty acids and glycerol. This process is made possible by lipoprotein lipases located on the walls of blood vessels. The fatty acids and glycerol are then absorbed by the liver for energy or taken up by adipose tissue and re-synthesized into triglycerides for storage purposes.
Fatty acid synthesis is activated during which of the following situations?
A. Increased levels of citrate and insulin, decreased levels of glucagon
B. Increased levels of citrate, decreased levels of glucagon and insulin
C. Decreased levels of citrate, increased levels of glucagon and insulin
D. Increased levels of citrate and glucagon, decreased levels of insulin
E. Decreased levels citrate and insulin, increased levels of glucagon
F. Decreased levels of citrate and glucagon, increased levels of insulin
A. Increased levels of citrate and insulin, decreased levels of glucagon
Explanation
Fatty acid synthesis is stimulated by insulin and inhibited by glucagon and epinephrine. The formation of fatty acids is catalyzed via the enzyme acetyl CoA reductase, which is activated by citrate. Acetyl CoA reductase is allosterically inhibited by palmitoyl-CoA. Fatty acid synthesis occurs in the cytosol and requires the use of ATP and NADPH, as this is a complex anabolic process.
A brief overview and important points of the pathway are as follows: Essentially, acetyl CoA combines with oxaloacetate (OAA) in the mitochondria to form citrate, which is then shuttled out into the cytosol by the citrate shuttle. Once in the cytosol, citrate is broken down again into its constituents, OAA and acetyl CoA. OAA is converted back into pyruvate to re-gain entry into the mitochondria. Acetyl CoA is converted to malonyl-CoA via acetyl CoA carboxylase (rate-limiting step and uses biotin as a cofactor). Malonyl CoA and the acyl carrier protein undergo several reactions to create fatty acid.
Glycolysis occurs at which location within a eukaryotic cell?
A. Mitochondrion B. Cellular membrane C. Endoplasmic reticulum D. Cytosol E. Nucleus
D. Cytosol
Explanation
Glycolysis is an important metabolic pathway that breaks down glucose into pyruvate. Then, pyruvate can either be converted anaerobically into lactate or undergo oxidative phosphorylation yielding 36 moles of ATP. Glycolysis occurs in the cytosol of a cell.
To help remember the above, think of this little rhyme: glycol occurs in the cytosol.
A 10-year old child presents in your office with a unilateral follicular conjunctivitis along with ipsilateral adenopathy. You correctly diagnose oculoglandular syndrome. Because it is the most common etiology, which of the following causes are you MOST likely to suspect?
A. Cat-scratch disease B. Toxoplasmosis C. Coccidioidomycosis D. Measles E. Diabetes
A. Cat-scratch disease
Explanation
Oculoglandular syndrome can be caused by a myriad of organisms and presents as a unilateral follicular conjunctivitis along with lymphadenopathy on the same side as the affected eye. Other signs and symptomology vary depending on the causative organism. Causes include but are not limited to: cat-scratch disease, tularemia, syphilis, tuberculosis, sprotrichosis, mononucleosis, coccidioidomycosis, sarcoidosis, Hansen’s disease, mumps, actinomycosis, Listeria and Herpes simplex.
Based solely upon the age of the child, one would first assume cat-scratch disease, which is the most common cause of oculoglandular syndrome. This assumption would be verified by asking if the child had recently been scratched by a cat and by performing the Hanger-Rose skin test for confirmation.
A 10-year old male is seen at your office complaining of itchy eyes and severe photophobia. He has a history of eczema and hay fever. Biomicroscopy reveals bilateral cobblestone papillae of the superior eyelids, ropy discharge, and mild superior corneal disruption that stains with sodium fluorescein. Given the above findings, what is your diagnosis?
A. Vernal keratoconjunctivitis (VKC)
B. Epidemic keratoconjunctivitis (EKC)
C. Bacterial conjunctivitis
D. Iritis
A. Vernal keratoconjunctivitis (VKC)
Explanation
VKC is a condition of the young and presents with an increased frequency in males. This type of allergy typically develops before age 14 and lasts for 4-10 years before the child outgrows it; VKC occurs predominantly in the spring and summer. The condition progressively lessens in severity, with the first episode being the worst. Usually VKC is seen in patients who are prone to atopy; therefore they suffer from eczema, asthma, or hay fever. Patients typically suffer from itchy eyes and photophobia. The condition basically presents as a very severe type of allergic conjunctivitis. Signs include cobblestone papillae of the upper lid, lid swelling, and ropy discharge that is worse in the morning. Corneal defects (usually superiorly) known as keratitis of Togby may also be present. Occasionally, patients will develop a shield ulcer and Trantas’ dots (calcified eosinophils seen circumlimbally that appear as chalky concretions), which may lead to the feeling of an associated foreign body sensation. Treatment includes mast cell stabilizers that should be started several weeks prior to re-occurring episodes, pulse steroid therapy, cool compresses, and sunglasses to help alleviate ensuing photophobia.
EKC and bacterial conjunctivitis typically do not cause extreme itching and should not present with cobblestone papillae.
The number one symptom associated with iritis is photophobia, and the patient should be neither complaining of itching nor have cobblestone papillae present on biomicroscopy.
A 24-year old female patient is seen at your office and reports that her eyes have been red for a few days. Biomicroscopy reveals bilateral diffuse superficial punctate keratitis (SPK) that stains with sodium fluorescein with no mucopurulent discharge. Based ONLY upon the corneal staining pattern, what is the MOST likely origin of her condition?
A. Bacterial
B. Viral
C. Dry eyes
D. Foreign body
B. Viral
Explanation
Diffuse SPK likely signals either a viral origin or a toxic reaction to solution or topical ophthalmic drops.
A bacterial etiology will cause staining of the inferior third of the cornea.
Interpalpebral corneal staining is usually caused by lagophthalmos or environmental desiccation.
A foreign body will either leave small punctate staining or tracks (especially if it is trapped under a contact lens).
A 32-year old male is seen at your office and is in a fair amount of pain. He can barely open his right eye and reports that the pain began this morning when he first opened his eyes. His medical history is unremarkable, and he does not wear contact lenses. His ocular history is remarkable for a mild corneal abrasion of the right eye from a tree branch that occurred over a month ago but had since healed. Biomicroscopy (after instillation of a topical anesthetic) reveals an epithelial defect 1.5 mm wide and 1.0 mm long that stains with sodium fluorescein. There is no anterior chamber reaction and no visible discharge. What is the MOST appropriate diagnosis?
A. Corneal abrasion
B. Corneal ulcer (microbial keratitis)
C. Recurrent corneal erosion
D. Epithelial basement membrane dystrophy
C. Recurrent corneal erosion
Explanation
This patient is suffering from a recurrent corneal erosion. These types of corneal defects frequently occur in response to a corneal abrasion incurred by something organic (like a fingernail or a tree branch). The initial abrasion heals, but a short time afterwards the patient will experience another episode without any incidence of trauma. The second occurrence tends to transpire first thing in the morning as the eyelids stick to that unstable flap of tissue overnight and rip it off like a band-aid when the eyes open. The best way to treat a recurrent corneal erosion is through the use of a topical antibiotic (unpreserved is best) to ensure sterility (as the cornea is exposed) as well as a bandage contact lens to speed up the healing process if the area of erosion is large. Hyperosmotic drops or artificial tears (preservative-free of course) should be prescribed for roughly 6-8 weeks (sometimes longer) to ensure healing and to allow for proper formation of hemidesmosomes that will help to alleviate future episodes. Other treatments include stromal micropuncture, debridement, phototherapeutic keratectomy (PTK), or oral tetracycline, which inhibits matrix metalloproteinases and allows for proper corneal healing.
A corneal abrasion occurs secondary to some type of trauma or injury, and this was not the case in the above example. Recurrent corneal erosions are a common occurrence with epithelial basement membrane dystrophies, but that is not the resultant diagnosis of the current problem experienced by the patient. An ulcer is ruled out on the basis that there is no active infection and is unlikely, as these more commonly occur in patients who wear contact lenses.
A 42-year old construction worker presents to you with a history of getting plaster in his right eye. He complains of pain, foreign body sensation, and photophobia. His acuity is reduced in that eye to 20/50 with a normal pupillary response. What type of chemical trauma did the worker experience, and what would be your first therapeutic intervention?
A. Acid burn and lavage eye with balanced saline solution for 30 minutes
B. Alkali burn and lavage eye with balanced saline solution for 30 minutes
C. Ultraviolet (UV) burn and lavage eye with balanced saline solution for 30 minutes
D. Thermal burn and lavage eye with balanced saline solution for 30 m
B. Alkali burn and lavage eye with balanced saline solution for 30 minutes
Explanation
Lime, particularly in the form of plaster, is the most commonly encountered alkali injury. Fortunately, it tends to cause a less severe burn than other types of alkali burns.
The rapidity with which pH abnormalities of the ocular surface are neutralized has a significant impact on the subsequent clinical course. Irrigation for a minimum of 30 minutes and checking pH of tears for evidence of neutrality is recommended.
The explanations for the alternative answers are as follows:
Acid burn and Lavage eye with balanced saline solution for 30 minutes;
plaster contains lime, which is alkali and not acid.
Thermal burn and lavage eye with balanced saline solution for 30 minutes;
there is no mention of heat (cigarette or matches) during the injury to the eye.
Ultraviolet (UV) burn and lavage eye with balanced saline solution for 30 minutes; UV burns usually are associated with delayed response after exposure to UV light.
A newborn presenting with symptoms of ophthalmia neonatorum 3 days after birth is MOST likely infected with which of the following organisms?
A. Chlamydia trachomatis B. Staphylococcus aureus C. Haemophilus influenza D. Streptococcus pneumonia E. Neisseria gonorrhoeae F. Herpes simplex virus
E. Neisseria gonorrhoeae
Explanation
Ophthalmia neonatorum is a conjunctivitis that typically develops within the first 3 weeks after birth as a result of transmission of infection from mother to child during delivery. This condition is particularly serious due to the lack of immunity in infants as well as the immaturity of the ocular surface (poor tear film and undeveloped lymphoid tissue).
Ophthalmia neonatorum secondary to N. gonorrhoeae typically develops within 2-5 days postpartum as hyperacute conjunctivitis. Most cases present bilaterally with periorbital edema, conjunctival chemosis, and excessive amounts of purulent discharge. It is extremely important to quickly and aggressively treat this infection due to the ability of N. gonorrhoeae to penetrate an intact corneal epithelium.
When C. trachomatis is the organism responsible for ophthalmia neonatorum, mild to moderate symptoms of unilateral or bilateral conjunctivitis commonly occur between 5 to 14 days after birth. C. trachomatis is the most common cause of ophthalmia neonatorum. These patients present with lid edema, conjunctival chemosis, punctate corneal opacities, and occasionally micropannus formation.
Other etiologies of ophthalmia neonatorum can include S. aureus, Haemophilus species, S. pneumoniae, E. coli, and P. aeruginosa. These pathogens are part of the normal bacterial flora of the female genital tract and are likely acquired as the newborn travels through the birth canal.
A patient walks into your office with a mild corneal abrasion, what is the correct healing sequence?
A. Basal cells at the wound margin flatten and spread-> attachment of cells via fibronectin and laminin-> mitosis of cells surrounding wound area-> hemidesmosome formation between basal cells
B. Basal cells at the wound margin flatten and spread-> mitosis of cells surrounding wound area-> attachment of cells via fibronectin and laminin-> hemidesmosome formation between basal cells
C. Mitosis of cells surrounding wound area-> attachment of cells via fibronectin and laminin-> hemidesmosome formation between basal cells-> basal cells at the wound margin flatten and spread
D. Hemidesmosome formation between basal cells-> basal cells at the wound margin flatten and spread-> mitosis of cells surrounding wound area-> attachment of cells via fibronectin and laminin
B. Basal cells at the wound margin flatten and spread-> mitosis of cells surrounding wound area-> attachment of cells via fibronectin and laminin-> hemidesmosome formation between basal cells
Explanation
Following minor corneal injuries, the main concern is for the cornea to seal off the wound and form tight junctions as quickly as possible to prevent edema and infection. The first phase following an abrasion is the sloughing off of superficial cells at the wound margin. This is followed by a flattening of basal cells surrounding the wound which then move into the damaged area via filpodia (extensions that allow for amoeboid-type motion). Mitosis rates increase surrounding the injury site to replace those cells that have migrated. The basal cells then secrete fibronectin and laminin to achieve transitory cellular attachment until the formation of hemidesmosomes. Once a basal cell comes in contact with another basal cell, a hemidesmosome forms signaling for a decrease in mitosis.
All else being equal, cells found in which layer of the cornea consume the GREATEST amount of oxygen?
A. Endothelium
B. Epithelium
C. Bowman’s membrane
D. Stroma
A. Endothelium
Explanation
The cells of the endothelium require the greatest amount of oxygen. This is due to the fact that endothelial cells maintain a steady state of corneal clarity and hydration. They actively pump out ions into the anterior chamber, which sets up an osmotic gradient that causes water to flow down its concentration gradient, thus preventing corneal swelling and opacification. However, because the endothelium is only one layer thick, in total this layer consumes 21% of the oxygen provided to the cornea. The stroma utilizes 39% of oxygen made available to the cornea, which is a low consumption rate considering that it makes up the bulk of the cornea. The epithelium is responsible for 40% of the oxygen consumed by the cornea. However, all else being equal, the endothelial cells consume the greatest amount of oxygen (140 X 10-5 ml of oxygen per sec), vs. stromal cells (2.85 X 10-5 ml of O2/sec) and epithelial cells (26.5 X 10-5 ml of O2/sec).
Axenfeld loops are smooth, dome-shaped, greyish-appearing nodules located under the bulbar conjunctiva that are a result of intrascleral looping of which of the following nerves?
A. Long anterior ciliary nerves
B. Long posterior ciliary nerves
C. Short posterior ciliary nerves
D. Short anterior ciliary nerves
B. Long posterior ciliary nerves
Explanation
Axenfeld loops are common findings on slit lamp examination that present as small, smooth, dome-shaped nodules most commonly located in the superior sclera. They often appear greyish in color, with occasional brown pigment surrounding the loop (observed particularly in patients with a darker iris). Axenfeld loops represent an anastomosis of a long ciliary nerve that turns to enter the sclera before looping back again to continue to its insertion at the ciliary body.
Chrysiasis of the cornea occurs secondary to administration of medication used to treat which of the following conditions?
A. Hypertension B. Cancer C. Diabetes D. Rheumatoid arthritis E. Cardiac arrhythmias
D. Rheumatoid arthritis
Explanation
Gold salts are used to manage rheumatoid arthritis, primarily when other treatment options have failed. Chrysiasis occurs secondary to the deposition of gold in the skin, lens, and cornea, causing a gray discoloration of the skin and brown/gold deposits in the deep stroma of the cornea.
Amiodarone is an anti-arrhythmic medication. Use of this drug commonly causes yellow/brown or white powdery corneal epithelial deposits located inferocentrally that appear to swirl outward while sparing the limbus. These deposits affect visual acuity minimally, if at all. The aforementioned deposits can also be observed in Fabry’s disease and in patients taking tamoxifen, chlorpromazine, chloroquine, or indomethacin.
During periods of severe hypoxia, the cornea will revert to anaerobic metabolism and break down glycogen. What layer of the cornea is capable of storing glycogen for use during times of hypoxia?
A. Endothelial layer
B. Epithelial layer
C. Descemet’s membrane
D. Stroma
B. Epithelial layer
Explanation
The epithelial cells store glycogen, which is used as an energy source when oxygen is not available. The stores can last for about 2 hours before being depleted. Once glycogen is no longer accessible, the cornea will not produce enough ATP and the epithelial cells will begin to die.
A back surface toric (spherical front surface) gas-permeable (GP) contact lens is ordered with base curve radii of 7.85 mm (43.00 D) and 8.44 mm (40.00 D). When verifying this lens with a lensometer you would expect to find approximately how many diopters of “induced cylinder”?
A. 1.50 D
B. 4.50 D
C. 3.00 D
D. 2.00 D
B. 4.50 D
Explanation
Assuming the 1-2-3 rule is correct, a base curve toric GP lens with a spherical front surface when analyzed will exhibit a difference in lensometry readings that are 3/2 the amount of the base curve difference measured in diopters. In the above case, the difference in the two measured base curve meridians is 3 diopters; therefore, if there is no toricity on the front surface (that is, this is not a bitoric GP); optically, the difference in the two raw powers measured by lensometry will be 4.50 diopters. For example, the powers could be measured to be 1.00 D in one meridian and -5.50 D in the meridian 90 degrees away, or +2.00 D and -2.50 D. Keep in mind that the 1-2-3 rule is based on the index of refraction (n) of the lens material. Most of today’s GP lenses have ‘n’ values that are in the 1.40 to 1.48 range. This range of ‘n’ will result in less difference in the measured lensometry powers. For our example of a 3.00 D base curve toric GP lens, the difference in lensometry powers might be 4.00 D for a GP lens fabricated in a material with a lower ‘n’.
A patient has a spectacle correction of +12.00 D. The vertex distance is 13 mm. What is the power at the corneal plane?
A. +12.00 D
B. +14.25 D
C. +11.25 D
D. +10.37 D
B. +14.25 D
Explanation
When a plus lens is moved from the spectacle plane to the cornea, you need to adjust the power by adding plus. So the only option in this question that is more plus than +12.00 D is +14.25 D. You can also use the following formula to arrive at the correct answer:
Fc = Fs/1-dFs Fc = Power at the corneal plane (diopters) Fs = Power at the spectacle plane (diopters) d = vertex distance (meters)
For our question Fc = +12.00/1-(0.013)(+12.00) = +14.22 D
An aphakic patient is seen at your office and wishes to be fit with contact lenses. What is an important contact lens parameter that MUST be considered in this patient’s care?
A. Ultraviolet (UV) inhibitor
B. Contact lens solution
C. Edge thickness
D. Contact lens material
A. Ultraviolet (UV) inhibitor
Explanation
Because this patient is aphakic, their retinas no longer receive the UV protection that is naturally provided by the crystalline lens. Although all of the above options should be included when deciding which type of lens to order, it is essential that you provide a UV inhibitor on the contact lens as well as sunglasses for this patient. When the contact lens power will be a high plus prescription, one should order a lenticular lens design to reduce lens thickness, help enhance centration, increase comfort as well as increase the Dk/t of the contact lens.
Hypoxia associated with hydrophilic (soft) contact lens wear can result in which of the following?
A. Corneal swelling
B. Corneal decompensation
C. 3/9 staining, scarring and pseudoptyergium
D. Blepharitis
A. Corneal swelling
Explanation
Hypoxia can cause corneal swelling (edema) acutely and corneal thinning chronically (by mobilization of glycosaminoglycans), can lead to secondary cornea neovascularization, both superficial pannus and occasionally deep stromal vessels, and endothelial changes including polymegathism and decreased cell numbers. Contact lens hypoxia, however, does not lead to corneal decompensation, blepharitis or peripheral 3/9 lesions which are more related to chronic rigid lens-induced exposure keratitis.
Dissection of the eye reveals that the ciliary body is actually triangular in shape. The apex of this triangle points in which direction and is continuous with which structure?
A. Points anteriorly; continuous with iris
B. Points posteriorly ; continuous with scleral spur
C. Points posteriorly; continuous with choroid
D. Points anteriorly: continuous with ora serrata
C. Points posteriorly; continuous with choroid
Explanation
The ciliary body is a band roughly 6mm wide and runs circumferentially internal to the sclera and posterior to the limbus. This structure is triangular in shape whose apex points posteriorly and is continuous with the choroid.
Free radicals can cause severe damage to tissue. Which of the following electrolytes can function as an antioxidant in the aqueous?
A. Sodium ions B. Ascorbate C. Albumin D. IgG E. Chloride ions
B. Ascorbate
Explanation
The aqueous humor contains many electrolytes including Na+, K+ , Cl-, HCO3-, glucose, lactate, amino acids, and ascorbate. Ascorbate is found in high concentrations in the aqueous (20x greater when compared to the concentration found in plasma). Ascorbate can serve as an antioxidant to eradicate free radicals reducing potential damage from ultraviolet light. Interesting note: the aqueous humor and tears of uncontrolled diabetics display higher levels of glucose than those of non-diabetics.
Iris colobomas form due to incomplete closure of the choroidal fissure. This usually results in a keyhole-shaped defect in which region of the iris?
A. Inferonasal
B. Inferotemporal
C. Superotemporal
D. Superonasal
A. Inferonasal
Explanation
An iris coloboma is an inferonasal, keyhole-shaped defect. The remainder of the iris is normal. Atypical colobomas may develop at sites other than the inferonasal area.
A 22-year old male presents in your office for his annual exam. Biomicroscopy reveals bilateral Krukenberg spindles and iris transillumination defects. Given the above findings, what is the correct diagnosis for this patient?
A. Posner-Schlossman syndrome
B. Pigmentary dispersion syndrome
C. Salzmann’s nodular degeneration
D. Pseudoexfoliation
B. Pigmentary dispersion syndrome
Explanation
Pigmentary dispersion syndrome generally occurs in young, myopic males with deep anterior chambers. This condition is caused by a disruption of the posterior iris pigment epithelium, causing this layer to rub against the ciliary zonules and release pigment into the anterior chamber and its associated structures. The aqueous in the anterior chamber displays convection currents. Warming inferiorly, aqueous rises and migrates forward towards the posterior surface of the endothelium, carrying pigment granules with it, then falls as it cools, causing the pigment to deposit vertically in a linear-fashion on the endothelium. Monitor these patients for blockage of the trabecular meshwork causing a rise in intraocular pressure (IOP) and potential glaucomatous damage to the optic nerve. Physical exertion as well as mydriasis may exacerbate pigment release; therefore, when dilating (especially with phenylephrine), you must be sure to measure post-dilated IOPs.
Salzmann’s nodular degeneration appears as blue/white hyaline plaque deposits between the epithelium and Bowman’s membrane, generally around the pupillary area of the cornea. This condition stems from other pathologies, primarily old phlyctenula. Treatment is generally not required unless vision is affected.
Posner-Schlossman syndrome causes an acute IOP spike, usually unilaterally and lasting for hours to weeks with recurrent episodes. Patients are often young and report decreased vision due to corneal edema, mild pain, and ocular redness. This syndrome is also known as glaucomatocyclitic crisis. Biomicroscopy will often reveal ciliary flush, a sluggish or dilated pupil, a mild anterior chamber reaction, potentially with keratic precipitates, corneal edema, open angles and normal optic nerves. IOP readings will normally range from 40-60 mmHg. The etiology is still uncertain; some have postulated that it may be of viral origin. Treatment includes (unless contraindicated) topical steroid drops, beta-blockers, and carbonic anhydrase inhibitors.
Pseudoexfoliation appears as white, flaky material that deposits along the pupillary margin, the anterior surface of the lens and other structures of the anterior chamber. This condition is usually unilateral and is seen in the elderly with a concurrent cataract. Transillumination defects, if present, are limited to the iris sphincter region. The pseudoexfoliative material can accumulate in the trabecular meshwork, causing an increase in IOP leading to glaucoma.
According to the Van Herick technique of angle estimation, which angle grade is considered MOST narrow and potentially capable of closure?
A. Grade 1
B. Grade 3
C. Grade 2
D. Grade 4
A. Grade 1
Explanation
The Van Herick method of angle estimation, although not infallible, is a good way of assessing the probability of angle closure with dilation. The temporal angle of a patient is evaluated by having the patient look straight ahead, placing the oculars of the slit lamp in the straight ahead position and shifting the lighthouse temporally so that an angle of 60 degrees is created. The beam is then narrowed to an optic section and placed at the temporal limbus. The width of the anterior chamber space at the angle is then compared to the width of the corneal optic section. The procedure is repeated and the illumination source is placed nasally to assess the grade of the nasal angle. If the angle space is equal to 1/2 or greater than the corneal optic section, the angle is not considered occludable and is given a grade of 4. A grade three displays an angle space that is less than 1/2 but greater than 1/4 of the width of the corneal optic section, and is considered safe to dilate. A grade two has an angle space that is roughly equal to 1/4 the width of the corneal optic section, and may be dilated but with caution. A grade 1 has an angle space of less than 1/4 the width of the corneal optic section, and requires gonioscopy to ensure that the patient is safe to dilate.
At what time period of the day would the aqueous humor production be least?
A. 8 AM to noon
B. Midnight to 6 AM
C. Afternoon
B. Midnight to 6 AM
Explanation
The precise role and receptors specificity of adrenergic mechanisms in regulating the rate of aqueous humor formation are unclear. Studies using fluorophotometry have shown that beta adrenergic antagonists unequivocally decrease aqueous humor formation, particularly aqueous humor production during sleeping hours, during which production is decreased by up to 50%. This decrease is due to the B-arrestin/cAMP cascade regulation from the beta-adrenergic receptors. This does not mean that the intraocular pressure necessarily decreases at night; in fact, nocturnal intraocular pressure spikes have recently been reported; these may have a role in causing progressive glaucomatous damage.
Goldmann applanation tonometry is calibrated for a central corneal thickness of roughly 520 micrometers. How will a cornea measuring 600 micrometers thick affect the intraocular pressure (IOP) measurements, and how should the IOP reading be compensated?
A. IOP will be falsely low; the measured IOP should be adjusted up
B. IOP will be falsely elevated; the measured IOP should be adjusted up
C. IOP will be falsely elevated; the measured IOP should be adjusted down
D. IOP will be falsely low; the measured IOP should be adjusted down
C. IOP will be falsely elevated; the measured IOP should be adjusted down
Explanation
A thicker than average cornea will cause a falsely elevated IOP measurement due to greater than normal corneal rigidity requiring more pressure to achieve proper indentation with the tonometer. Therefore, the resultant IOP should be adjusted down. The magnitude of the adjustment depends on how much the central corneal thickness deviates from the calibrated thickness of 520 micrometers.
How is the temporal modulation transfer function expected to change in a person with early glaucoma not yet manifesting any defects on visual field testing?
A. Decreased sensitivity to low and moderate frequencies
B. Decreased sensitivity to moderate frequencies only
C. Decreased sensitivity to low temporal frequencies only
D. Decreased sensitivity to moderate and high temporal frequencies
D. Decreased sensitivity to moderate and high temporal frequencies
Explanation
Early glaucomatous damage can be difficult to detect because intraocular pressure and visual fields can be normal. Recent studies demonstrate that the magno cells may be damaged early on in glaucoma. The magno cells are a part of the “where” pathway and therefore display excellent temporal resolution. Due to this factor, there is evidence that clearly reveals a correlation between an altered temporal modulation transfer function and early glaucoma, with a marked decrease noted for the moderate and high temporal frequencies, even though the respective visual field is free of defects.
Instillation of too much fluorescein when attempting Goldmann applanation tonometry will result in what type of erroneous result?
A. Mires that are misaligned superiorly
B. A corneal abrasion
C. A measured intraocular pressure that is higher than the true intraocular pressure
D. Mires that are misaligned inferiorly
E. A measured intraocular pressure that is lower than the true intraocular pressure
C. A measured intraocular pressure that is higher than the true intraocular pressure
Explanation
There are many potential sources of error when performing Goldmann applanation tonometry. If the mires created by the prisms in the tonometer are not aligned properly, the resulting IOP measurement will not be accurate. This also applies if too little or too much fluorescein is instilled. Too little fluorescein causes thin mires and an underestimation of the IOP reading. Too much fluorescein results in large mires and a falsely elevated measurement. If the mires are misaligned inferiorly (that is, the majority of the mires are located below the prism line) then the slit lamp needs to be lowered to center the mire images. If the mires are misaligned superiorly then the slit lamp needs to be raised to center the mires.
A corneal abrasion may occur if the slit lamp is moved excessively or if too much force is placed by the tonometer head against the cornea.
An elderly patient presents in your office with decreased visual acuity. He remarks that he can read better without his glasses and his refraction denotes a large myopic shift. Dilated fundus exam is unremarkable. Which of the following slit lamp findings would MOST likely explain the above findings?
A. Bilateral limbal girdle of Vogt
B. Bilateral corneal arcus
C. Bilateral 3+ nuclear sclerosis of the lens
D. Bilateral crocodile shagreen
C. Bilateral 3+ nuclear sclerosis of the lens
Explanation
Nuclear sclerosis is caused by changes to the optical clarity of the lens. As we age, proteins precipitate out of the lens matrix, causing the lens to become cloudy and altering its density. As time passes, the lens will also begin to change color from clear to a yellow/brown in a process called lens brunescence. Cataracts also generally cause a myopic shift with an increase in against-the-rule astigmatism, leading to decreased distance vision but improved near vision.
Corneal arcus is caused by lipid deposition in the peripheral cornea. There remains a characteristic clear zone between the lipid and the limbus. Arcus does not generally interfere with vision.
Crocodile shagreen and limbal girdle of Vogt are also benign corneal findings commonly seen in the elderly. Crocodile shagreen appears in the peripheral cornea as polygonal white opacities. Limbal girdle of Vogt is noted at the 3 o’clock and 9 o’clock interpalpebral positions as white crescent-shaped opacities.
Long-term use of corticosteroids can lead to the formation of which of the following types of cataract?
A. Cortical
B. Posterior subcapsular
C. Anterior subcapsular
D. Nuclear sclerotic
B. Posterior subcapsular
Explanation
The possible formation of posterior subcapsular cataracts (PSC) is a common concern in patients undergoing long-term treatment with corticosteroid therapy. PSCs have been associated with the use of systemic, topical, ophthalmic, topical dermatologic, nasal aerosol, and inhalation type steroids. This relationship is likely dose-dependent, and the usual time from beginning steroid treatment to the onset of lens changes is 1 year (with a dosage of 10 mg/day of prednisone) but has been observed in as short as 2 months with as little as 5 mg/day. Patients with PSC formation may complain of an increase in light sensitivity, photophobia, glare, or difficulty reading. If visual acuity is notably decreased, surgical removal of the lens may be warranted.
Berger’s space is created by an interval between which two structures?
A. The anterior face of the lens and the posterior surface of the iris
B. The equator of the lens and the ciliary body
C. The posterior surface of the cornea and the anterior face of the iris
D. The posterior face of the lens and the anterior vitreous
D. The posterior face of the lens and the anterior vitreous
Explanation
Berger’s space is created by the separation between the posterior face of the lens and the anterior face of the vitreous.
The space between the equator of the lens and the ciliary body is known as the circumlental space
Patients with a history of homocystinuria are MOST likely to experience crystalline lens subluxation in which of the following directions?
A. Up and inward
B. Down and inward
C. Down and outward
D. Up and outward
B. Down and inward
Explanation
Common ocular sequelae that have been associated with a diagnosis of homocystinuria include ectopia lentis (bilateral crystalline lens subluxation), retinal detachment, and secondary glaucoma. In most cases of ectopia lentis, the lens is more likely to be displaced downward and inward in homocystinuria (as compared to upward and outward in Marfan’s syndrome). Additionally, in homocystinuria, the lens zonules are markedly abnormal, the lens does not accommodate, and up to 1/3 of the cases of lens subluxation eventually completely dislocate into the vitreous or anterior chamber. Due to the severity of systemic and cardiovascular complications associated with homocystinuria (thrombosis and occlusion), patients presenting with ectopia lentis should be screened for this disease using the sodium nitroprusside test to measure homocysteine in the urine.
Purkinje images are caused by reflections of objects on the cornea and lens. Which of the four images moves forward with accommodation?
A. I
B. III
C. IV
D. II
B. III
Explanation
There are four Purkinje images. The first image is caused by reflection from the anterior corneal surface and is the brightest of the images. The first image is roughly the same size as the object. The second Purkinje image is formed by the posterior surface of the cornea and almost coincides with the first Purkinje image. The third Purkinje image is the largest and is caused by reflection off of the anterior plane of the crystalline lens. The fourth Purkinje image is the smallest and is inverted, formed by reflection off of the posterior surface of the lens.
During the process of accommodation the anterior surface of the lens moves forward. The image that is reflected off of this surface is Purkinje III. Purkinje image III will be seen to move forward during accommodation.
The ligaments that suspend the lens (zonules) are embryonically derived from what structure?
A. The primary vitreous
B. The tertiary vitreous
C. The lens capsule
D. The lens epithelium
B. The tertiary vitreous
Explanation
The zonules are attached to the posterior and anterior surfaces of the lens and connect to the pars plana of the ciliary body. The primary vitreous develops from weeks 3 through 9. The secondary vitreous then begins to form and condenses the primary vitreous forming Cloquet’s canal. Developmentally, the tertiary vitreous is secreted last; the zonules are comprised of condensed tertiary vitreous.
A 42-year old patient reports that her right eye has been watery and she has mild pain, redness, and swelling in the lower medial canthal region. You suspect dacryocystitis as the cause of her symptoms. Which of the following procedures is NOT appropriate when further evaluating this possible diagnosis?
A. Exophthalmometry
B. Dilation and irrigation of the lacrimal system
C. Extraocular muscle motility
D. Digital palpation of the medial canthal area
E. Gram stain and blood agar cultures of discharge
B. Dilation and irrigation of the lacrimal system
Explanation
The evaluation of a patient suspected of dacryocystitis should involve a detailed case history including a discussion of any previous episodes with similar symptoms, or the presence of any concomitant ear, nose, or throat irritation/infection. External examination of the patient should include the application of gentle pressure to the lacrimal sac region in order to attempt to express any discharge from the punctum; this should be done bilaterally. If any discharge can be recovered, a Gram stain or blood agar culture is helpful in determining the type of bacteria present. In addition to these tests, extraocular motility and evaluation for the presence of proptosis should be completed to rule out orbital cellulitis. In atypical, severe, or non-responding cases, a computed tomography scan (CT) should be considered. It is important to remember that probing, dilation, and/or irrigation of the lacrimal system should not be attempted during an acute infection of the lacrimal gland. This may cause the infection to spread to other areas such as the throat
A common cause of epiphora in infants is caused by a small membrane that covers over which of the following structures?
A. The puncta
B. The valve of Hasner
C. The lacrimal gland
D. The canaliculus
B. The valve of Hasner
It is common for mothers of young infants to note that one eye (or both eyes) of her infant constantly tears in conjunction with the presence of mucopurulent discharge. This epiphora results from a blockage of the nasolacrimal passageway caused by a membrane covering the valve of Hasner. The majority of blockages will self-resolve without intervention (80-90% of infants) within the first 12 months of life. Treatment may include massage of the nasolacrimal sac several times a day in an effort to rupture the membrane.
An 81-year old female reports that her eye has been watering more frequently over the past month; you decide to administer the primary Jones dye test (Jones I). After 5 minutes, the application of a cotton-tipped applicator to the inferior turbinate reveals the presence of dye in the area. Taking this into consideration, what is the MOST likely cause of the patient’s epiphora complaint?
A. Dysfunction of the valve of Hasner B. Punctal stenosis C. Hypersecretion of tears D. Partial nasolacrimal duct obstruction E. Complete nasolacrimal duct obstruction
C. Hypersecretion of tears
The primary Jones dye test can be utilized to determine the patency of the nasolacrimal system. 1-2 drops of fluorescein are instilled into the inferior fornix of the eyes while the patient is in an upright position and blinking her eyes normally. After a period of 5 to 10 minutes, a cotton-tipped applicator is used to swab the undersurface of the inferior turbinate on each side of the nasal passage.
When the primary Jones dye test is positive (dye is recovered from the inferior turbinate of the nose), practitioners may conclude that the system is patent and that no significant blockage of the nasolacrimal drainage structure is likely. However, minor stenosis or physiologic dysfunctions cannot be completely ruled out. Patients who have a positive result on the Jones I test are more likely to experience symptoms of epiphora that are secondary to primary oversecretion of tears, rather than a dysfunction in lacrimal drainage (as in the above question).
When the primary Jones dye test is negative, the probability of an obstruction or dysfunction in lacrimal drainage is much greater; however, this test alone is not sufficient to document this conclusion. The secondary Jones dye test is then necessary to determine the severity and location of the obstruction.
Chronic blepharitis, if left untreated, can cause which of the following structural changes to the anterior ocular segment?
A. Tristichiasis
B. Madarosis
C. Distichiasis
D. Hypertelorism
B. Madarosis
Blepharitis is a condition caused by pathogens, usually of Staphylococcus origin, that colonize along the eyelid margins. The bacteria produce exotoxins which take the form of flakes and are generally seen along the base of the eyelashes. Unfortunately, this condition is chronic but will wax and wane in its presentation. Long-term complications include madarosis (missing lashes), trichiasis, neovascularization of the eyelid margin, keratitis, erythema, phlyctenule formation and infiltrates. Patients may complain of dry, irritated eyes, stinging, pain, itching, frequent eye infections, foreign body sensation, and decreased acuity (if there is corneal involvement). Treatment includes eye lid scrubs, antibiotic ointments and sometimes transient topical steroid use to decrease lid inflammation (usually used in conjunction with a topical antibiotic). Occasionally oral antibiotics are prescribed, especially in the event of poor compliance.
Distichiasis is a rare congenital phenomenon marked by an absence of meibomian glands. In the place of the meibomian glands is an extra row of eyelashes.
Hypertelorism is a term used to describe the incidence in which the orbits are located quite far apart. This generally occurs along with other congenital cranium anomalies.
Tristichiasis is a very rare occurrence in which a person possesses three rows of eyelashes.
Dacryoadenitis refers to an inflammation or infection of which of the following ocular structures?
A. The puncta
B. The lacrimal sac
C. The lacrimal gland
D. The nasolacrimal sac
C. The lacrimal gland
Dacryoadenitis describes inflammation of the lacrimal gland, generally due to infection. The swelling is categorized as either chronic or acute. Acute presentations appear more commonly as a unilateral swelling of the upper eyelid, along with pain, excessive lacrimation, probable ipsilateral lymphadenopathy, and potential proptosis. If the condition is bilateral it is likely due to a systemic infection. Chronic dacryoadenitis is generally bilateral and presents with hard masses that are palpable at the location of the lacrimal gland. This form is often painless and caused by inflammatory diseases such as Grave’s, Sjogren’s, or sarcoidosis. The chronic type warrants further investigation in order to rule out a lacrimal gland tumor.
In addition to the meibomian glands which other accessory glands secrete oil?
A. Wolfring and Krause
B. Zeiss and Moll
C. Zeiss and Wolfring
D. Moll and Krause
B. Zeiss and Moll
The glands of Zeiss and Moll are accessory oil glands located on the lid margins adjacent to the base of the lash follicles. The lipid layer of the tear film is superficial and as such it is exposed to the environment protecting the aqueous layer from evaporation.
The glands of Wolfring and Krause are located deep in the fornix of the eyelids and serve to secrete a portion of the aqueous layer of the tear film.
Many skin anomalies may mimic malignant lesions. Which of the following skin conditions has the HIGHEST risk of becoming malignant?
A. Papilloma
B. Seborrhoeic keratosis
C. Actinic keratosis
D. Cutaneous horn
C. Actinic keratosis
Actinic keratosis is a precursor to squamous cell carcinoma and appears as scaly, dry skin that does not heal. People with skin that is of lighter pigmentation along with excessive exposure to ultraviolet light tend to be most at risk for development of this condition.
Papillomas may take on various forms and may be viral or non-viral in origin. They can commonly be found on the eyelids or surrounding orbital skin. Viral warts tend to grow at an accelerated rate while non-viral papillomas are fairly slow to grow. Papillomas can mimic neoplastic growths so be sure to rule this out while watching carefully for color change, ulceration, lash loss, bleeding, and vascularization.
Cutaneous horns or tags are also benign and are likely a form of papilloma but appear to involve more keratin. Treatment is similar to that of a papilloma.
Seborrhoeic keratosis is more commonly seen in middle-aged and elderly persons. This benign, epidermal growth is quite superficial and does not extend into the dermis. It appears like a brown plaque that has been stuck onto someone’s skin. The borders are very distinct and there may be some elevation. The lesions may be removed if the patient is concerned about cosmesis
Numerous reports have suggested that increased tear film osmolarity is a key consequence in dry eye. Although osmolarity is not easily measured in the clinical setting, tear osmolarity increases in most dry eye sub-types due to which of the following processes?
A. Reactive oxygen species are increased in the tears of most dry eye sub-types; this increases osmolarity
B. The lipid layer is altered in most dry eye states, leading to ion pairing
C. Decreased capillary exchange leads to ionic bonding
Patients with dry eye tend to blink less than normals, leading to increased evaporation
D. Loss of tear stability induces an increased evaporation rate, leading to increased osmolarity
E. In aqueous tear deficiency, the lacrimal gland produces more ionic species
D. Loss of tear stability induces an increased evaporation rate, leading to increased osmolarity
Tear instability leads to greater evaporation and higher osmolarity through a mechanism of concentration of the remaining tears, since only the aqueous tear portion evaporates rather than the ionic species. Several studies have indicated that normal tear osmolarity is less than or equal to 300 Osm/L, with values exceeding 308 Osm/L indicating increased osmolarity. As a single measure, tear osmolarity has recently been found to correlate the best (r squared 0.55) to dry eye severity of several clinical tests in a large, multi-center study (Sullivan et al., IOVS 51:6125-6130, 2010).
Oral acyclovir is most effective for patients presenting with eyelid findings associated with herpes zoster if administered within which of the following periods following the onset of the disease?
A. 4-5 days B. 72 hours C. 10-12 hours D. 24 hours E. 7-10 days
B. 72 hours
Oral acyclovir is the mainstay of therapy for patients diagnosed with herpes zoster ophthalmicus. This systemic treatment is maximally beneficial of it is initiated within 72 hours from the onset of the disease (usually the appearance of eyelid lesions). The use of oral acyclovir typically results in quick resolution of skin vesicles, decreases the amount of pain the patient experiences, and reduces the duration of viral shedding and appearance of new lesions. Acyclovir has also been shown to significantly reduce the incidence of ocular findings such as episcleritis, keratitis, and iritis. The recommended dosage is 800mg orally 5 times per day for 7-10 days.
Ptosis can be caused by dysfunction or damage to which of the following muscles?
A. Superior tarsal muscle (muscle of Muller)
B. Muscle of Horner
C. Inferior rectus
D. Pars ciliaris (Riolan’s muscle)
A. Superior tarsal muscle (muscle of Muller)
Ptosis is a condition in which the upper eyelid sags. It can be caused by dysfunction of either the superior palpebral levator or the superior tarsal muscle (muscle of Muller). Because the levator is the major muscle responsible for raising the upper eyelid, ptosis from levator damage is often more severe then ptosis from dysfunction of the muscle of Muller.
The muscle of Horner (also known as the pars lacrimalis) is part of the palpebral portion of the orbicularis oculi. The fibers for the muscle of Horner come from the lacrimal crest and encircle the lacrimal canaliculi. This assists the flow of tears into the nasolacrimal drainage system when the orbicularis oculi contracts to close the eye. The muscle of Riolan (also known as the pars ciliaris) is another section of the palpebral portion of the orbicularis oculi; it lies near the lid margin to maintain the margins next to the globe. The orbicularis oculi is the major muscle responsible for closing the eyelids.
Tear volume in a normal, healthy, young adult measures approximately between which of the following values?
A. 17.0-20.0 microliters B. 2.0-5.0 microliters C. 13.0-16.0 microliters D. 9.0-12.0 E. 6.0-8.0 microliters
E. 6.0-8.0 microliters
Tear volume has been measured by several methods to be approximately 6-7 microliters in normal individuals, with lesser values occurring in conditions of aqueous tear deficiency. This has implications for drug delivery, since the normal ophthalmic drop volume varies between 25 and 50 microliters, effectively overwhelming the native tear value upon instillation.
The lymphatic system serves many important roles in the human body. The lateral portion of the eyelid lymphatics drain into which of the following structures?
A. The puncta
B. The submandibular lymph node
C. The conjunctiva
D. The pre-auricular lymph node
D. The pre-auricular lymph node
The lateral 2/3 of the upper lid and the lateral 1/3 of the lower lid lymphatics drain into the pre-auricular lymph node located directly in front of the ear. The medial 1/3 of the upper eye lid and the medial 2/3 of the lower lid lymphatics drain into the submandibular node located just under the jaw-line. Therefore, it is very important to evaluate these two nodes separately, especially when a condition of viral etiology is suspected
A 2.5x Galilean telescope has a -25D ocular lens. When focused for infinity, what is the length of the telescope?
A. 5 cm B. 6 cm C. 14 cm D. 4 cm E. 10 cm
B. 6 cm
Explanation M = -Doc/Dobj where Doc=power ocular; Dobj= power objective; t= separation of lenses 2.5= - (-)25/Dobj Dobj= 10D t= f'obj + f'oc f'obj=1/10D = 0.10 m f'oc = 1/-25D = 0.04 m
t=0.10 + -0.04 = 0.06 m or 6 cm
10 cm - incorrect- would come up with this answer if only took in account the focal length of the objective lens.
4 cm - incorrect- would come up with this answer if only took in account the focal length of the ocular lens.
14 cm - incorrect - would come up with this answer if thought equation was t= f’obj + f’oc
A patient is using a stand magnifier of +16D with a +2.00 add. If the distance separating the two lenses is 25 cm what is the equivalent power of this combination?
A. 22D
B. 26D
C. 10D
D. 18D
C. 10D
Explanation
De= D1+D2 -tD1D2 where De=equivalent power;D1=power of magnifier;D2=power add;t=separation in meters between the lenses
De = (16+2) - 0.25(16)(2) De= 18-8 = 10D
18D- incorrect answer -would come up with this if added the stand magnifier power to the power of the add
22D -incorrect answer - would come up with this if added 16D for stand mag 2D for add and 4D for equivalent of 25cm.
26D - if added the 18 +8 in the De equation instead of subtracting
Illumination is one of the most important considerations to discuss in the case disposition for a visually impaired patient. A patient with chronic open angle glaucoma moves a 60 watt bulb on a flexible mounted arm from three feet to one foot from the page. The illumination on the page will appear to have been increased by how much?
A. Decreased by 1/9 of the original brightness
B. Should be the same brightness
C. Increased by 9 times the original brightness
D. Decreased by 1/3 of the original brightness
E. Increased by 3 times the original brightness
C. Increased by 9 times the original brightness
It has been said that prescribed optical devices without consideration of the appropriate lighting will often doom the patient to failure. Unfortunately, there are no good tests to determine the exact type of lighting. Generally, different light levels are tried during the examination (as well as during the training session) with the patient using an adjustable light. The distance from the page is very important because of the inverse-square law of illumination: the intensity varies inversely as the square of the distance from the page. If the light is moved from 1 foot to 3 feet from the page, a bulb will be needed that is approximately nine times as bright to keep the same illumination on the page. (It should be noted that technically, this relationship is only true for a point source of light.) Clinically, however, it gives a good approximation of the change in brightness (illumination) seen on the page when the distance of the light is changed. The illumination in the above example would therefore increase by 9X when the bulb is moved towards the page.
One of your tech-savvy low vision patients wishes to use a CCTV for reading. The CCTV operates on what principle of magnification?
A. Relative distance magnification
B. Rated magnification
C. Equivalent magnification
D. Relative size magnification
D. Relative size magnification
CCTVs work on the principle of relative size magnification (or projection). It operates by enlarging the text without lenses in front of the patient or the patient moving closer to the device. When the print is enlarged electronically in this matter, the image of the print subtends a larger area on the retina and thus a larger size.
An example of relative distance magnification would be if you were holding a newspaper at 40 cm and you moved it closer to 20 cm. The print now appears 2 times as large relative to the 40 cm distance.
Rated magnification is often used by manufacturers of some hand magnifiers and stand magnifiers using a 25 cm reference distance.
The visual acuity of a 77 year-old female patient with age-related macular degeneration is 2/16 in the right eye on the ETDRS chart. Why is this chart useful in monitoring the response to treatment with anti-vascular endothelial growth factor (VEGF)?
A. Each line has 5 Sloan letters throughout the chart with equal spacing and is 1.26 times larger than the line below it; each line is .1 log units larger than the line below it when moving up the chart
B. The Snellen construction of the chart enables the examiner to quickly note that a two-line increment represents a factor of a two time increase in the size of the letters
C. A three-line decrease represents a factor of a two time decrease in the size of the letters
D. Each line is 1.0 log units larger than the previous line
A. Each line has 5 Sloan letters throughout the chart with equal spacing and is 1.26 times larger than the line below it; each line is .1 log units larger than the line below it when moving up the chart
Explanation
The ETDRS chart is a logarithmic eye chart modeled after the Bailey-Lovie chart. It is the primary standardized eye chart used in evaluating the visual acuity of low vision patients. The ETDRS charts are logMAR (log of the minimum angle of resolution) in design and are constructed with 10 Sloan sans serif letters. Each line is 1.26 times larger than the line below, and the construction of each line is such that the difficulty is theoretically equivalent on every line.
The construction of the ETDRS chart is made to eliminate the inherent errors in the measurement of visual acuity found in the traditional non-standardized Snellen test charts. The Snellen test charts have variations in legibility of different letters as well as differences in the spacing between the lines of letters and between adjacent letters on single lines. The ETDRS logarithmic chart is constructed in such a way that each line of letters is 0.1 log units (about 1.26 times) larger than the previous line. This is a geometric progression.
A positive catalase test indicates that a bacteria is capable of breaking down which of the following?
A. Glucose
B. Hydrogen peroxide
C. Pyruvate
D. Carbon dioxide
B. Hydrogen peroxide
Catalase is an enzyme commonly found in organisms that are exposed to oxygen. Catalase breaks down hydrogen peroxide into oxygen and water. The catalase test is performed by applying a drop of hydrogen peroxide to a microscope slide. A colony of bacteria is then exposed to the hydrogen peroxide via an applicator stick. The presence of bubbles or froth yields a positive catalase test. Staphylococci and Micrococci are catalase-positive organisms. Campylobacter and Escherichia coli are catalase-negative organisms.
Antibiotic resistance that is rapidly spread within a population of bacteria is due to what mechanism?
A. Binary fission
B. Transformation
C. Budding
D. Conjugation
D. Conjugation
Conjugation occurs between a donor (possesses a conjugative plasmid) and recipient bacteria. The donor bacterium initiates contact with the recipient via a sex pilus, allowing for cell-to-cell contact and transfer of DNA. The plasmids often contain genes that encode for toxin production, virulence factors, and antibiotic resistance. Genetic transformation is achieved by very few strains of bacteria and may only occur during certain phases of growth; therefore, rapid antibiotic resistance is not feasible. Budding and binary fission are means of reproduction but are not directly responsible for antibacterial resistance. Genes must have been transferred that code for resistance prior to budding and binary fission in order for the progeny to contain genes that allow for drug resistance.
Congenital cataracts can be caused by a viral infection of the mother with rubella virus (German measles) during development of the primary lens fibers. At which time period in embryonic development can infection cause congenital cataracts?
A. 2nd trimester B. Post-delivery C. 1st trimester D. Conception E. 3rd trimester
C. 1st trimester
Explanation
The developing lens is susceptible to rubella virus when the lens fibers are forming, which occurs around weeks 4-7 of gestation. Earlier infection will occur prior to lens fiber development, and the lens is resistant to later infection because the virus is unable to penetrate the lens capsule.
The fetus is most susceptible to lenticular damage during the first trimester. Contraction of the rubella virus will cause the greatest amount of damage during this time period. Congenital cataracts are usually detectable at birth but may be seen later because the virus can persist in the lens.
A 12-year old male is sitting in your waiting room while his mother undergoes her annual eye exam. While waiting, he eats a candy bar containing peanuts, and, as luck would have it, he is deathly allergic to nuts. To counter anaphylactic shock, what would be the BEST course of action?
A.Prednisone (oral)
B. Injection of epinephrine (EpiPen)
C. Olopatadine (Patanol)
D. Administration of Benadryl (oral)
B. Injection of epinephrine (EpiPen)
Explanation
Anaphylactic shock is defined as a severe, multi-system, type I hypersensitive, acute allergic reaction that may be life-threatening. Signs of an allergic reaction include tingling, itching, hives, swelling of lips and tongue, constriction of the airway, vasodilation, myocardial depression, and a decrease in blood pressure. The EpiPen is injected intramuscularly to the upper lateral thigh to ensure rapid delivery. Epinephrine (Adrenaline) activates both alpha and beta adrenergic receptors causing an increase in peripheral vascular resistance and allowing for an increase in blood pressure and coronary artery perfusion. Adrenaline also serves to reverse vasodilation and decrease urticaria and angioedema. For severe, life-threatening reactions, Benadryl (diphenhydramine) will not work quickly enough. Topical antihistamines have little if any systemic absorption and therefore will not be effective in counteracting the anaphylaxis. While oral steroids may be useful in the post-management of anaphylactic shock, they will not yield the desired immediate response.
