opro prep random

Question 1

Which 2 of the following newborn characteristics are considered the PRIMARY risk factors for the development of retinopathy of prematurity? (Select 2)

Maternal pre-eclampsia

Birth weight of less than 2000g

Respiratory distress syndrome

Gestational age less than 32 weeks

Gestational age of less than 28 weeks

Birth weight of less than 1500g

Answer 1

Gestational age less than 32 weeks

Birth weight of less than 1500g

The two primary risk factors for development of retinopathy of prematurity (ROP) are low birth weight (newborns weighing less than 1500g) and prematurity (babies born less than 32 weeks gestation).

• Some degree of ROP can be observed in 25-30% of infants weighing less than 1500g
• 65% of infants weighing less than 1250g at birth
• Of the two, low birth weight is the greatest risk factor
• Other risk factors occur at a lower rate, including intraventricular hemorrhage, respiratory distress syndrome, sepsis, and sleep apnea

It is for these reasons that all newborns that fall under the category of “higher risk” of retinopathy undergo a thorough retinal examination as soon as possible. This screening should include indirect ophthalmoscopy or wide-field retinal imaging beginning at 4-7 weeks of age with subsequent review at 1-2 week intervals until the retinal vascularization reaches the temporal periphery.

Question 2

According to the Bohr Effect, which of the following statements is TRUE?

A lower pH favors oxygen release from hemoglobin into the tissues

A higher pH favors release of oxygen from the tissues to hemoglobin

A lower pH favors oxygen release from the tissues to hemoglobin

A higher pH favors release of oxygen from hemoglobin into the tissues

Answer 2

A lower pH favors oxygen release from hemoglobin into the tissues

The Bohr Effect describes the effect of pH on the capability of hemoglobin to bind oxygen. A lower pH (drives the reaction to the right) favors the release of oxygen from hemoglobin into the tissues. Please reference Equation 1.

During exercise, muscles produce lactic acid and carbon dioxide which decreases the pH of blood (increases hydrogen ion concentration). The change in pH signals hemoglobin to release more oxygen to the tissues that are now oxygen-deprived. Higher pH levels will shift the reaction to the left and cause less oxygen to be delivered to tissues.

Question 3

Which type of leukocyte is responsible for producing antibodies?

Memory T cells

B cells

Lymphocytes

T helper cells

Answer 3

B cells

T and B cells both fall under the heading of lymphocyte. During an immune response, an antigen is swallowed by a macrophage. The antigens are broken apart into fragments and become bound to major histocompatibility complex (MHC) molecules, forming antigen-MHC complexes. The complexes are recognized by virgin cytotoxic T cells and virgin helper T cells. The virgin cytotoxic T cells divide into effector T cells and memory T cells. The virgin T helper cells undergo differentiation into memory T cells and effector helper T cells. The memory T cells are stored for future encounters. The effector helper T cells promote mitosis of T and B cells to help combat the pathogens. Helper T cells do not kill any pathogens but help direct the immune system and the appropriate cells. Cytotoxic T cells are also known as killer T cells because upon contact with a target, they inject chemicals that cause death to the target cell. Virgin B cells, upon activation by effector helper T cells and interleukins, begin mitosis and differentiate into memory B cells and effector B cells. The new memory B cells are stored for future encounters. The effector B cells produce antibodies which serve to inactivate the offending agent.

Question 4

Patients with which of the following colored irides are MOST likely to experience increased iris pigmentation with prolonged use of a topical prostaglandin?

Gray

All irides, regardless of color, possess an equal risk for increased iris pigmentation

Light brown

Blue

Answer 4

Light brown

Research has demonstrated that patients with light brown or green/brown eyes are most at risk for developing increased iris pigmentation associated with topical prostaglandin use. The pathogenesis of this side-effect appears to be linked with increased activity of tyrosinase in melanocytes, resulting in increased cellular melanin levels as opposed to an increased number of melanocytes.

Question 5

What is the equivalent logMAR acuity of 20/60?

0. 50
1. 60
2. 33
3. 48

Answer 5

0.48

The logMAR acuity is determined by taking the log of the reciprocal of the decimal acuity. For the above Snellen fraction 20/60, the decimal acuity is found by dividing the numerator by the denominator. 20/60 = 0.333. Now take the log of the reciprocal which gives us log (1/0.333) = 0.478 or 0.48.

Question 6

The non-silicone hydrogel lens type that tends to absorb the LEAST protein is which of the following?

High water, non ionic (group 2)

Low water, ionic (group 3)

Low water, non ionic (group 1)

High water, ionic (group 4)

Answer 6

Low water, non ionic (group 1)

The current FDA classification system for soft contact lenses is currently under review. A new material classification will include silicone hydrogels. Group 1 lenses tend to absorb the least amount of protein.

Question 7

Which of the following is NOT considered an increased risk factor for the development of a rhegmatogenous retinal detachment?

Cataract surgery

Fuchs’ dystrophy

Family history

Myopia

Answer 7

Fuchs’ dystrophy
Patients may possess certain characteristics that can represent an increased risk for the development of a retinal detachment, including a history cataract surgery, myopia, family history, and the presence of certain systemic diseases. Cataract surgery is known to increase the risk for developing a retinal detachment, especially if any complications occur. Patients who are myopic are also more prone to a retinal detachment, with the higher degree of myopia, the higher the risk factor. Family history is also relevant in that there may be certain genetic factors that promote inflammation and photoreceptor degeneration, which can lead to an increased risk of a retinal detachment. Additionally, systemic diseases such as Marfan syndrome, Stickler syndrome, and Ehlers-Danlos syndrome have been associated with an increased risk of retinal detachments.

Question 8

Your 38 year-old male patient wears rigid gas-permeable contact lenses. The following parameters are for his right eye:
Keratometry: 45.50 @ 090 x 44.00 @ 180
Base curve of RGP: 44.00 (apical alignment)
Over-refraction: +0.50 -1.00 x 180
Which 2 of the following would you expect to occur to the over-refraction if you suspect that his contact lens is warped by 0.50D? (Select 2)

The equivalent diopter sphere of the over-refraction will not change

The equivalent diopter sphere of the over-refraction will become plus

The equivalent diopter sphere of the over-refraction will become minus

The amount of with-the-rule astigmatism in the over-refraction will decrease

The amount of with-the-rule astigmatism in the over-refraction will increase

The amount of with-the-rule astigmatism in the over-refraction will not change

Answer 8

The equivalent diopter sphere of the over-refraction will not change
The amount of with-the-rule astigmatism in the over-refraction will increase

If the cornea is WTR–>original over refraction is WTR = the amount of WTR astigmatism in the new over-refraction will increase (by the amount of warp)

If cornea ATR + Orginal over refr is ATR=
the amount of ATR astigmatism in the new over-refraction will increase (by the amount of warp)

if Cornea is WTR+ over refraction is ATR = ATR decrease
The amount of ATR astigmatism in the new over-refraction will decrease (warp/flexure actually helps here)

Question 9

Scotopic vision is mediated primarily by which type of receptor in the retina?

S-cones

Rods

Ganglion cells

Cones

Answer 9

Rods
Under dim illumination, we tend to rely on rods to maximize visual sensitivity. Scotopic vision is mediated primarily by rods; as a result, this leads to heightened sensitivity to low lighting but at the cost of poor acuity (20/200) and little to no color vision. Photopic vision, on the other hand, occurs in bright light and is characterized by phenomenal acuity (20/20), color discrimination, and is dominated by cones.

Question 10

Which of the following individuals is MOST likely to possess large pupils?

A 7 year-old Asian, hyperopic male with brown eyes

A 57 year-old African-American, myopic male with brown eyes

A 68 year-old Caucasian, hyperopic female with hazel eyes

A 12 year-old Caucasian, myopic female with blue eyes

Answer 10

A 12 year-old Caucasian, myopic female with blue eyes

Patients who are near-sighted, young or possess lighter-colored irides typically exhibit larger pupils than patients who are hyperopic, older, or have darker-colored irides. Pupil size typically diminishes with age.

Question 11

Which of the following types of cataracts is the MOST detrimental to visual acuity?

Anterior subcapsular

Sutural

Posterior subcapsular

Nuclear sclerotic

Answer 11

Posterior subcapsular
Posterior subcapsular cataracts (PSC) are the result of cellular migration from the equator to the posterior pole and tend to affect visual acuity to a greater degree than other types of cataracts due to the fact that they are closest to the posterior nodal point of the eye and are located on or near the visual axis. Patients with PSCs will complain of decreased acuity in bright light and to a lesser degree in low light. This asymmetrical disruption of visual acuity in varying light levels stems from changes in pupil size. In bright light the pupils constrict, creating a small aperture that is covered over by the opacification. In low lighting conditions, the pupils dilate allowing for greater lens exposure most of which is not opacified (or at least to a lesser degree) resulting in improved vision.

Question 12

The choriocapillaris is separated from the retina by a thin membrane. What is the name of this membrane?

Bruch’s membrane

Sattler’s membrane

Bowman’s membrane

Descemet’s membrane

Answer 12

Bruch’s membrane

Bruch’s membrane lies between the choriocapillaris of the choroid and the retinal pigment epithelium of the retina. Although this membrane is very thin (about 2 microns thick) it is very complex. The membrane consists of five facets. The outermost component is the basement membrane of the choriocapillaris followed by the outer collagenous zone, the elastic layer, the inner collagenous zone and most internally the basement membrane of the retinal pigment epithelium.

Sattler’s membrane is actually a layer of vessels in the choroid located externally to choriocapillaris.

Bowman’s and Descemet’s membranes are found in the cornea.

Question 13

you notice a palpable flat elevation of the skin on the left upper lid of your 73 year-old male patient that is about 2.5cm in diameter. What is the proper dermatological term for this type of lesion?

Macule

Papule

Nodule

Vesicle

Plaque

Answer 13

Plaque

Plaque: a palpable but flat lesion of the skin that is greater than 0.5cm in diameter. Plaques may have well-defined, or ill-defined borders.

• Macule: a localized area of color change without any associated infiltration or elevation (the surface is smooth). The lesion may be pigmented (as in a freckle), hypopigmentation (vitiligo), or erythematous (in a capillary hemangioma). The area of change is typically less than 1.5cm in diameter.
• Papule: small palpable lesions in which there is a solid elevation of the skin. These lesions are usually less than 0.5cm in diameter, may be flat-topped or dome-shaped, and may be a single lesion or present as multiple lesions.
• Vesicle: a small fluid-filled lesion that is typically less than 0.5cm in diameter. There may be a single lesion or multiple lesions.
• Nodule: a solid area of elevated skin; a papule that is enlarged in three dimensions (height, width, and length).

Question 14

Which of the following statements regarding the bicarbonate buffering system found in our blood is TRUE?

Hypoventilation increases the concentration of carbon dioxide, lowering the pH of the blood

Hypoventilation decreases the concentration of carbon dioxide, resulting in an increase in the pH of blood

Hyperventilation increases the concentration of carbon dioxide, causing the blood to become more acidic

Hyperventilation decreases the concentration of carbon dioxide, resulting in an increase in the production of hydrogen ions

Answer 14

Hypoventilation increases the concentration of carbon dioxide, lowering the pH of the blood

buffer is an agent that serves to maintain the desired pH of its respective system. Buffers are comprised of a weak base and a weak acid. Bicarbonate is used by our body to resist drastic changes in pH. Hypoventilation causes the blood to become more acidic (lower pH) by causing an increase in the production of hydrogen ions due to an increase in the concentration of carbon dioxide in the lungs and blood.
Hyperventilation results in an increase in the pH of blood (more basic) due to a decrease in the concentration of carbon dioxide, which results in a decrease in hydrogen ion production.

Question 15

A patient presenting with neurosyphilis is MOST likely to exhibit which of the following pupil conditions?

Relative afferent pupillary defect

Unilateral Argyll Robertson pupil

Absolute afferent pupillary defect

Unilateral Adie’s tonic pupil

Bilateral Argyll Robertson pupil

Bilateral Adie’s tonic pupil

Answer 15

Bilateral Argyll Robertson pupil

Bilateral Argyll Robertson pupils are a highly specific sign found in patients with neurosyphilis. In these cases, patients typically present with small pupils that do not respond well to light but will exhibit significant constriction when fixation on a near object occurs. This is usually bilateral but may be asymmetrical. This particular finding is also known as “light-near dissociation.” The exact pathophysiology of this condition is not completely known; however, most investigators believe that syphilis damages the intercalated neurons that make the connection between the pretectal nucleus and each Edinger-Westphal nuclei.

There are other conditions that may cause bilateral light-near dissociation such as diabetes, myotonic dystrophy, Parinaud’s dorsal midbrain syndrome, familial amyloidosis, encephalitis, and chronic alcoholism. Disorders that may result in unilateral light-near dissociation include Adie’s tonic pupil, herpes zoster ophthalmicus, and aberrant regeneration of the 3rd nerve

Question 16

The following classes of drugs are all considered the first line of treatment for systemic hypertension. Which class is associated with transient myopia?

Diuretics

Calcium channel blockers

Angiotensin receptor blockers (ARB)

Angiotensin-converting enzyme inhibitors (ACE)

Answer 16

Diuretics

The choice of initial treatment of hypertension is complex and depends on co-morbidities. ACE and ARBs are the current preference. ACE inhibitors are available generically and thus are cheaper, but increasingly ARBs (notably Cozaar® (losartan)) are being made available generically. Calcium channel blockers are popular but less so than ACE and ARB, which work on the Renin system. The finding of transient myopia, while not common, is not altogether rare and should always be considered in patients on thiazide diuretics.

Question 17

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?

1. 50 D
2. 00 D
3. 00 D
4. 00 D

Answer 17

1.00 D

To solve this problem, input the values into the equation for a single surface power, F = n’-n/r where F= the power of the lens, n’= the index of the medium that light is entering (the lens), n= the index of the medium in which light is exiting (medium surrounding the lens; in this case, air), and r = the radius of curvature (in meters) of the lens. Solve for F = 1.50-1.0/0.5 = 1.00 D.

Question 18

Which of the following steroids is LEAST likely to contribute to the formation of posterior subcapsular cataract (PSC) formation?

Loteprednol

Fluorometholone

Prednisolone

Dexamethasone

Rimexolone

Answer 18

Loteprednol

Research has demonstrated that ester-based steroids possess the least likelihood of causing a PSC. To date, the only ester-based topical ophthalmic steroid is loteprednol. Loteprednol possesses an ester group in the carbon 20 position rather than a ketone group. Posterior capsular cataract formation occurs as a result of the interaction between the ketone group and lens proteins, causing the formation of a Schiff base intermediate and eventually leading to PSC development. Because loteprednol does not contain a ketone group, the probability of PSC formation is significantly diminished.

Question 19

Your 23 year-old rigid gas-permeable contact lens wearer returns to your office for a contact lens follow-up after wearing his new lenses for about 2 weeks. During slit-lamp evaluation you notice several circular, well-demarcated indentations of the central cornea that pool with fluorescein. What is the name of this finding?

Dimple veiling

3-9 staining

Superficial punctate keratitis

Dellen

Answer 19

Dimple veiling

Dimple veiling is a finding that occurs almost exclusively in rigid gas-permeable contact lens wearers (but can occur with scleral lenses due to mucin ball formation). Several circular, well-demarcated indentations are found in the cornea, either central or peripheral, that pool with fluorescein (they do not stain, as they do not represent breaks in the corneal epithelium). Dimple veiling is caused by a sub-optimal fitting relationship of a rigid gas-permeable contact lens in which tiny air bubbles that become trapped beneath the contact lens and are then mechanically compressed by the lens, indenting the cornea. Patients are typically asymptomatic; however, if sufficient in number, the dimples may interfere with vision, producing glare, hazy vision, and/or a loss of contrast sensitivity.

Dimple veiling is transient and will resolve within a few hours if the contact lens is removed from the cornea. Longer-term treatment involves modification of the fitting relationship of the contact lens, such as flattening the base curve, decreasing the optical zone diameter, blending the junction between the base curve and peripheral curve, or steepening the peripheral curves to allow for better tear exchange beneath the lens.

Dimple veiling has also been shown to occur in a few cases of soft contact lens wear. In these cases, mucin balls composed of mucus, lipids, and proteins can build up on the contact lens and create a similar corneal finding.

Question 20

What is the MOST common complication of a posterior vitreal detachment?

Vitreous hemorrhage

Retinal hemorrhage

Central scotoma

Retinal detachment

The perception of a floater

Answer 20

The perception of a floater

Syneresis and liquification of the vitreous are part of the normal aging process, but they also may cause a posterior vitreal detachment (PVD). Generally, PVDs occur without complication except for the perception of an annoying floater by the patient which will regress somewhat with time. Rarely, a PVD can cause a retinal tear which may lead to a retinal detachment, epiretinal membranes, and vitreal and retinal hemorrhages. Monitor the patient carefully to ensure that none of these complications develop and be sure to educate patients regarding the signs and symptoms of a retinal detachment.

Question 21

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?

Epithelial basement membrane dystrophy

Corneal abrasion

Recurrent corneal erosion

Corneal ulcer (microbial keratitis)

Answer 21

Recurrent corneal erosion

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.

Question 22

Which of the following conditions places the patient at a higher risk of posterior capsular rupture during cataract surgery or dislocation of the intraocular lens implant after surgery?

Multiple sclerosis

Systemic lupus erythematosus (SLE)

Pseudoexfoliation syndrome

Glaucoma

Answer 22

Pseudoexfoliation syndrome

A patient with pseudoexfoliation syndrome, despite removal of the cataract, can still produce pseudoexfoliative material, which can further weaken the zonules. The weakening of the lenticular zonules can lead to dislocation of the intraocular lens implant, which is usually placed in the posterior capsule. Patients with this condition are also are an increased risk for rupture of the posterior capsule. A patient with pseudoexfoliation syndrome and iridodonesis will commonly have a capsular tension ring inserted at the time of cataract removal surgery; frequently, the IOL will either be placed in the sulcus or sutured in place to prevent dislocation. Patients with pseudoexfoliation syndrome are typically referred for cataract surgery as soon as the cataracts become clinically significant in order to minimize complications associated with the removal of dense cataracts. Although patients with multiple sclerosis and SLE may experience ocular complications associated with these conditions or their treatments, they are not at a higher risk of lens dislocation or posterior capsular rupture during phacoemulsification.
Pseudoexfoliation syndrome: pathological manifestations of relevance to intraocular surgery.

Question 23

Which of the following is classified as a first-generation antihistamine (blocks H-1 receptors)?

Cetirizine (Zyrtec®)

Diphenhydramine (Benadryl®)

Loratidine (Claritin®)

Fexofenadine (Allegra®)

Answer 23

Diphenhydramine (Benadryl®)

explanation - Diphenhydramine (Benadryl®) is considered a first-generation antihistamine and therefore is more likely to cause drowsiness and central nervous system dysfunction, resulting in impairment of cognitive function or performance. The second-generation oral antihistamines were designed to greatly reduce, if not eliminate, this side effect. Second-generation H-1 blockers include Allegra®, Claritin®, and Zyrtec®.

Question 24

The receptive field of which type of cell of the visual system displays a heightened sensitivity to a stimulus moving in a specific direction (the cell is directionally selective)?

Rod cells

Correct answer Complex cells

Amacrine cells

Ganglion cells

Simple cells

Answer 24

The receptive fields of rod cells, ganglion cells and amacrine cells do not possess any preference for stimulus direction. They do respond differently to various brightness intensities and spot sizes. The receptive fields of simple cells respond preferentially to dark and light edges or bars that are of a specific orientation and thus have receptive fields that are split into antagonistic inhibitory and excitatory areas.

Complex cells, like simple cells, prefer elongated stimuli of specific orientation; however, unlike simple cells, placement of the stimulus within a specific area of the receptive field is not critical. The stimulus can be placed anywhere within the receptive field of a complex cell and will elicit a response from the cell. Complex cells do, however, display a preference for direction. A stimulus moving in a certain direction will manifest a cellular response, whereas the same stimulus, if moved in the opposite direction, will not elicit a response. Also, the receptive fields of complex cells do not possess inhibitory and excitatory regions

Question 25

our patient’s best corrected acuity measured 10/160. What magnification would be required to read 0.8M text?

4x magnification

8x magnification

6. 4x magnification
7. 2x magnification

Answer 25

8x magnification

0/160 = 20/320 Goal is 0.8M = Reduced Snellen 40 320/40 =8x

If the student did not convert the acuity to the 20ft notation and used 160/40, they would have arrived at 4x as the answer. 6.4x would have been the conclusion if 50 had been used instead of 40; 0.8M = Reduced Snellen 40, not RS 50. If the 10 foot equivalent was used, also mistaking 0.8M for Reduced Sellen 50 instead of 40, 3.2x would have been found as the answer; 160/50 = 3.2x.

Question 26

Modern rigid gas-permeable (GP) contact lenses are usually fitted to adhere with which of the following parameters?

Maximize tear exchange for appropriate re-supply of oxygen

Maximize lens movement

Align with the anterior corneal surface and maintain tear exchange

Spare the corneal apex from undue pressure and rubbing during wear

Answer 26

Align with the anterior corneal surface and maintain tear exchange

Modern GP CLs are usually fitted to align with the corneal surface and maintain tear exchange, but there is no need to maximize tear exchange for oxygen supply reasons as the lenses themselves are permeable to oxygen. Lenses for keratoconic eyes are often fitted to spare the corneal apex; this is not the normal paradigm for non-keratoconic eyes.

Question 27

Which of the following is an example of functional glaucoma progression?

Superior notching of the rim tissue observed with a direct ophthalmoscope

A superior arcuate visual field defect

Thinning of the inferior nerve fiber layer as indicated by optical coherence tomography (OCT)

A Drance hemorrhage observed at the disc margin

Answer 27

A superior arcuate visual field defect

functional progression occurs when the natural performance of the element in question has been altered. Functional glaucoma progression is measured via visual field testing. Any defects/changes observed on visual field testing should be re-tested to ensure that the defect/change is repeatable. Many times, observed misses will not occur upon re-testing. Many clinicians believe that it is important to perform many visual field tests during the first year of diagnosis to establish a proper baseline as well as to allow for the determination of the rate of progression. Although there is no current agreed up value that indicates if a patient displays a fast rate of progression, many clinicians consider a change of 1.5 decibels or greater per year to be a fast rate of progression. Newer software allows for easier detection of progression by comparing visual field results across time and extrapolating a graph of the visual field index. A steeper slope indicates a faster rate of progression. A Drance hemorrhage, superior notching of the rim tissue, and an abnormal OCT scan are considered structural signs of glaucoma progression.

Question 28

A newborn presenting with symptoms of ophthalmia neonatorum 3 days after birth is MOST likely infected with which of the following organisms?

Staphylococcus aureus

Streptococcus pneumonia

Neisseria gonorrhoeae

Haemophilus influenza

Herpes simplex virus

Chlamydia trachomatis

Answer 28

Neisseria gonorrhoeae
( GO NOW) ONLY after bord 2-5 days

Explanation :
Trachoma occur
( 5-14 days ) after born

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.

Question 29

Which of the following immune cells require activation by an antigen-presenting cell to be activated?

Natural killer cells

Cytotoxic T cells (CD8+)

Macrophages
T helper cells (CD4+)

Neutrophils

Answer 29

T helper cells (CD4+)

Neutrophils and macrophages can both act as antigen-presenting cells (APCs) and do not require APC activation. Natural killer cells are lymphocytes that are neither T nor B in phenotype. They can respond against virally infected cells and some tumor cells, but they do not have specific antigen recognition sites. CD8+ cytotoxic T lymphocytes interact primarily with major histocompatibility complex I (MHC I) directly on infected cells. CD4+ T helper cells interact with MHC II on APCs, which activates them to stimulate other B and T cells to proliferate. These cells must recognize the specific antigen on an antigen-presenting cell to become activated.

Question 30

Which of the following is a co-morbid condition that simultaneously affects a large percentage of patients diagnosed with myasthenia gravis?

Sleep apnea

Thyroid disease

Hypertension

Diabetes mellitus

Lung carcinoma

Thymus gland abnormalities

Answer 30

Thymus gland abnormalities

Approximately 75% of patients diagnosed with myasthenia gravis have concurrent thymus gland abnormalities; of these patients, 85% show hyperplasia or germinal center formation. Encapsulated tumors or thymomas occur in the remaining 10-30% of these patients. In patients diagnosed with ocular myasthenia only, the overall risk of thymoma is reduced to approximately 4%. Due to the relationship between the occurrence of myasthenia gravis and thymus gland abnormalities, it is thought that the thymus may play a significant role in the autoimmune response seen in this condition. In addition to thymus gland abnormalities, patients with myasthenia gravis also tend to have an association with hyper and/or hypothyroidism (3-15%), rheumatoid arthritis (5%), and systemic lupus erythematosus (2%)

Question 31

When analyzing a rigid gas-permeable (RGP) contact lens, you measure base curves of 7.30 (46.25) and 7.54 (44.75) with a radiuscope, and -3.75 and -6.00 on lensometry. What type of toric gas-permeable contact lens design do you have?

Spherical

Toric Base Curve

Front Surface (F1) Toric

SPE Bitoric

CPE Bitoric

Answer 31

Toric Base Curve

The first measurement that should be made when analyzing RGP contact lenses is lensometry. Lenses should be placed concave side down on the aperture stop, and the power and axis wheels should be rotated until mires are clear and lined up. If cylinder is present, powers should be recorded in both major meridians (record gross amounts). After lensometry, lenses should be analyzed using the radiuscope. Again, once the sharpest focus of mires is found, both base curves should be measured and recorded. Base curves should be converted from millimeters to diopters. The steep meridian is recorded over the flat meridian, and the most plus meridian goes with the flat meridian.

For the above patient, the measurements are as follows:
46.25 -6.00
44.75 -3.75
The next step is to determine the values of the difference in base curves and the difference in contact lens power. For this patient, the difference in base curves is 1.50D and the difference in contact lens power is 2.25D.
- If the difference in base curve is multiplied by 3/2 and that value is equivalent to the contact lens power then you have a Toric Base Curve lens (with spherical front surface)
o For this patient (3/2) x (1.50) = 2.25 and difference in CL power = 2.25
o 2.25 = 2.25 therefore, this is a Toric Base Curve lens design
o Note that “equivalent” is defined as less than or equal to 0.50D
- If the difference in base curve is equal to the difference in contact lens power then you have a spherical power effect (SPE) bitoric lens design
- If the difference in base curve is not equivalent to the difference in CL power, and 3/2 x the difference in base curve is also not equal to the difference in CL power then you have a cylinder power effect (CPE) bitoric lens

Question 32

Scalp tenderness and intermittent jaw claudication are virtually pathognomonic for which of the following systemic conditions?

Giant cell arteritis

Rheumatoid arthritis

Tolosa-hunt syndrome

Ramsay hunt syndrome

Polyarteritis nodosa

Answer 32

Giant cell arteritis

Giant cell arteritis (or temporal arteritis) is a granulomatous inflammatory vasculitis that has a predilection for medium and large-sized arteries. It particularly tends to affect the superficial temporal artery, and in some cases the ophthalmic, posterior ciliary, and proximal vertebral arteries as well. Characteristic features associated with giant cell arteritis include scalp tenderness that is typically noted when combing the hair, headache (which may be localized), pain and stiffness in the proximal muscle groups (which is typically worse in the morning), and other non-specific manifestations including neck pain, weight loss, malaise, fever, night sweats, and depression. Symptoms of intermittent jaw claudication are virtually pathognomonic in cases of giant cell arteritis. Pain in association with speaking and chewing occur due to ischemia of the masseter muscle.

Polyarteritis nodosa is a collagen vascular disease that has a predilection for medium and small arteries. Tolosa-hunt syndrome is a rare condition that is characterized by extraocular nerve palsies including the 3rd, 4th, 5th, and 6th cranial nerves. Ramsay hunt syndrome is a disorder that occurs secondary to reactivation of pre-existing herpes zoster virus in the nerve bundle of the facial nerve.

Question 33

An incident ray of light on a flat mirror has an angle of 65 degrees from the normal; what is the angle of the reflected ray measured from the normal?

155 degrees

115 degrees

25 degrees

65 degrees

Answer 33

65 degrees

Remember that for the law of specular reflection, the angle of incidence is equal to the angle of reflection. The angle of incidence is measured from the angle made between the incident ray and the normal. The angle of reflectance is measured from the angle made between the reflected ray and the normal.

Question 34

Which portion of the midbrain is involved in the integration of visual information?

The cerebellum

The thalamus

The tectum

The inferior olivary nucleus

The cerebrum

Answer 34

The tectum

The tectum lies in the midbrain and is responsible for the integration of visual and auditory input.

The cerebellum specializes in the coordination of unconscious motor activity to achieve balance and maintain spatial orientation. The cerebellum is not part of the midbrain.

The thalamus, the hypothalamus, and the cerebrum are classified as belonging to the forebrain. The thalamus serves as a relay for sensory information and projects these sensory signals to the appropriate destination. The hypothalamus largely functions to maintain homeostasis of internal organs via influencing behaviors to maintain internal ‘status quo’. The cerebrum is responsible for processing and integrating sensory input and motor responses.

The inferior olivary nucleus is thought to play a role in motor function and motor learning as it is closely associated with the cerebellum.

Question 35

Which of the following oral antihistamines will most likely cause mydriasis and dry mouth?

Diphenhydramine (Benadryl®)

Fexofenadine (Allegra®)

Cetirizine (Zyrtec®)

Loratadine (Claritin®)

Answer 35

Diphenhydramine (Benadryl®)

Question 36

Which of the following human leukocyte antigen (HLA) types is associated with Bechet’s syndrome?

HLA-B27

HLA-B51

HLA-B7

HLA-A29

HLA-DR2

Answer 36

HLA-B51

Question 37

What is the approximate volume of the vitreous?

2. 0 ml
3. 0 ml
4. 0 ml
5. 0 ml

Answer 37

4.0 ml

Question 38

Eukaryotic cells create new genomes through genetic exchange via which mechanism?

Generalized transduction

Sexual reproduction

Conjugation

Transformation

Answer 38

Sexual reproduction

Question 39

Oral non-steroidal anti-inflammatory drugs (NSAIDs) such as Aspirin, Ibuprofen, and Naproxen help to decrease pain and inflammation by which mechanism?

Blockage of nociceptors

Inhibition of cyclooxygenase-1 and -2 (COX-1, COX-2)

Anabolism of prostaglandins

Synthesis of arachidonic acid and thromboxane

Answer 39

Inhibition of cyclooxygenase-1 and -2 (COX-1, COX-2)

Question 40

What is the membrane potential of a photoreceptor in the dark?

+40 mV

+60 mV

• 40 mV
• 60 mV

Answer 40

-40 mV

In the darkness the membrane potential of a photoreceptor is around -40 mV. Some texts quote that the resting potential of an unstimulated photoreceptor cell is -20 mV, others state -50 mV whereas others quote -40 mV. Regardless of the value, the important thing to note is that normal cells have resting potentials of around -70 mV which is more negative than photoreceptors. This fact is attributable to the dark current which makes a photoreceptor’s resting potential slightly more positive.

Question 41

Which 2 of the following are TRUE in regards to central and peripheral suppression? (Select 2)

A-In peripheral suppression, the image from the peripheral retina of the deviating eye is suppressed to avoid confusion

B- In peripheral suppression, the image from the peripheral retina of the deviating eye is suppressed to avoid diplopia

C-In central suppression, the image from the fovea of the deviating eye is suppressed to avoid diplopia

D- In central suppression, the image from the fovea of the deviating eye is suppressed to avoid confusion

Answer 41

B-In peripheral suppression, the image from the peripheral retina of the deviating eye is suppressed to avoid diplopia

D-In central suppression, the image from the fovea of the deviating eye is suppressed to avoid confusion

Confusion refers to the simultaneous perception of two dissimilar images that are superimposed upon one another. In order to avoid confusion, the image from the fovea of the deviating eye is suppressed.

Pathological diplopia is the simultaneous appreciation of two images of the same object in two different positions. In order to avoid diplopia, the image from the peripheral retina of the deviating eye is suppressed.

Question 42

Which of the following is considered the “master” endocrine gland?

The hypothalamus

The pineal gland

The pituitary gland

The thalamus

Answer 42

The pituitary gland

The pituitary gland is roughly about the size of a pea but it is a powerful gland. The anterior pituitary is responsible for synthesizing and secreting the thyroid-stimulating hormone, the growth hormone, prolactin, the adrenocorticotrophic hormone, the follicle-stimulating hormone, the luteinizing hormone, and the melanocyte-stimulating hormone. The posterior pituitary lobe stores oxytocin and the antidiuretic hormone. Due to the fact that it is capable of regulating a large number of bodily functions and processes, it is aptly known as the master gland.

The thalamus, the hypothalamus, and the cerebrum are classified as belonging to the forebrain. The thalamus serves as a relay for sensory information and projects these signals to the appropriate destination. The hypothalamus largely functions to maintain homeostasis of internal organs via influencing behaviors to maintain the internal ‘status quo’.

The pineal gland plays a role in the regulation of circadian rhythms.

Question 43

Which of the following types of aberration have been shown to play a major role in how the eye detects defocus and responds with the normal reflex accommodative response?

Spherical aberration

Radial astigmatism

Trefoil

Longitudinal chromatic aberration

Curvature of field

Coma

Answer 43

Longitudinal chromatic aberration

Studies have shown that longitudinal chromatic aberration (LCA) plays a very important role in how the eyes detect defocus, resulting in an accommodative response. There is a significant amount of LCA present in the human eye; this occurs due to the fact that the refractive index of any medium (other than a vacuum) varies with wavelength. Therefore, shorter wavelengths (blues) will bend more as they pass through a lens, while longer wavelengths (reds) bend less. This leads to a variation in the image location, also known as LCA. If the LCA is removed by using monochromatic light or by optically neutralizing the LCA, it has been proven that a significant disruption occurs in the normal reflex accommodative response.

Question 44

A patient reports horizontal diplopia. Cover testing reveals 16 prism diopters of exophoria at distance. Which of the following will MOST likely cause the phoria to become less exophoric or more esophoric?

Vision therapy with an emphasis on convergence training

Prescribing plus-powered spectacles

Prescribing minus-powered spectacles

Vision therapy with an emphasis on divergence training

Answer 44

Prescribing minus-powered spectacles

16 at distance = dive excess
to fix it:
1- vision therapy but usually VT does not change the value of measured phoria
2- give (-) lens to make him converg

Vision therapy generally does not change the value of the measured phoria but instead serves to increase the compensatory mechanisms so that the patient no longer experiences symptoms. Prisms or spectacles can alter the value of the measured phoria. In a pre-presbyopic patient, prescribing minus-powered glasses causes stimulation of the accommodative system, which in turn activates the vergence system and results in convergence and therefore a decrease in exophoria or an increase in esophoria.

Question 45

Which of the following glaucoma medications has the FASTEST PEAK onset of action?

Timolol maleate 0.5%

Brimonidine tartrate 0.1%

Bimatoprost

Latanoprost

Answer 45

Timolol maleate 0.5%

Timolol maleate blocks both beta1 and beta2 adrenergic receptors and serves to decrease intraocular pressure. The effects of timolol ophthalmic solution may be observed as early as one half hour after drop instillation, reaching peak efficiency at one- to two-hours post-instillation.

Brimonidine tartrate is an alpha-2 adrenergic receptor agonist causing increased uveoscleral outflow and decreased aqueous production. Topical ocular administration results in peak IOP reduction levels two hours after instillation.

Latanoprost is a prostaglandin analog and decreases intraocular pressure (IOP) by increasing uveoscleral outflow. Its effects reach peak effectiveness roughly two hours after use.

Bimatoprost is also a prostaglandin analog and causes IOP reduction via increasing both uveoscleral and trabecular meshwork outflow. Its effects can be observed four hours after instillation, reaching peak effectiveness at eight to twelve hours after instillation.

Question 46

Inflammation of the corneal stroma without the involvement of the epithelium or endothelium is known as which of the following conditions?

Neurotrophic keratitis

Interstitial keratitis

Corneal hydrops

Infiltrative keratitis

Bullous keratopathy

Answer 46

Interstitial keratitis

• Interstitial keratitis (IK) is an inflammation of the corneal stroma in the absence of primary involvement of the corneal epithelium or endothelium. It is most often associated with congenital syphilis but may occur with other conditions such as tuberculosis, leprosy, Lyme disease, and other viral infections.

Question 47

After completing a subjective refraction on your patient, you obtain the following best-corrected visual acuities: OD: 20/20, OS: 20/50. You wish to perform a balance test. Which of the following balance tests is the MOST appropriate to perform?

Prism dissociation balance test

Red/green balance test (bichrome)

Alternating occlusion

Cover testing

Answer 47

Red/green balance test (bichrome)

for unequal acuity

The bichrome test is useful when acuities are unequal between the eyes; it can also be used as a general balance test when acuities are equal. This test is performed by occluding one eye and projecting letters on a red and green background. The patient is initially fogged about + 0.50 D. Fogging generally over-plusses the patients such that they report that the letters are blacker and bolder on the red side of the chart, meaning that there is a need to add minus lenses or reduce plus power. The red should appear blacker/bolder with over-plussing because this shifts the chromatic interval forward, causing objects projected on a background with longer wavelengths (red) to be bolder. The addition of minus lenses should equate the two sides such that the letters appear equally black and bold. If the patient initially reports that the letters on the green side are bolder, then either plus lenses need to be added or minus lenses need to be reduced to shift the chromatic interval forward. Erroneous responses may occur with a patient suffering from cataracts or a red-green color defect.

Prism dissociation and alternating occlusion both require equal acuities between the eyes and therefore are of little value for this particular patient. Cover testing is not considered a binocular balance test.