Midterm 1 Flashcards
Biomicroscope (Slit lamp)
Primary evaluating tool of the anterior segment of the eye. Two combined systems: Illumination system and observation system.
Slit lamp illumination system: 2 types
With focusable beam with well-defined edges. Filters to enhance view or exam. It works on Vogt (Kohler) illumination principle: produces homogeneous slit beam and prevents disruption of light beam on ocular surface. Haag streit type (vertical illumination system with bulb at top of tower); Zeiss type (round housing unit at middle of instrument with bulb encased, most common at SCO)
Slit lamp observation system
High-resolution microscope with variable magnification, eyepieces and objective lenses.
Slit lamp Magnification System: 3 types
Contains convergent or parallel eyepieces. Many objective lenses create a wide range of magnification levels. Grenough/Flip-type; Galilean rotating barrel (switches mag, ones used in clinic); Zoom.
Slit lamp design
Magnification system, Illumination system, Light intensity, joystick, and lock, power on/off. Chin adjustment (align outer canthus with the line on the slitlamp bar)
Patient Education on Slip lamp
Why are you performing the test: to examine health of the eye. Remind them to keep their forehead against the forehead rest, chin on the chin rest and keep mouth closed
Slit length and width
Continuous, fixed-width and height
Filters on slit lamp
Neutral density, yellow, cobalt blue, red free
Alignment of Microscope and Light, parfocality
The point at which the microscope is focused corresponds to the point on which the light is focused, this coupling effect is called parfocality. This is achieved by the microscope and the illumination system, having a common focal plane and their common axis of rotation also lies in that focal plane.
Slitlamp filters
Diffuser: used for general, nonfocal illumination, used for anterior segment photography. Used to observe large gross areas of eye on low magnification
Cobalt Blue: used in fluorescent exams as exciter filter, terms yellow dye bright green.
Red-free (green): Used to enhance contrast between blood vessels and their surroundings
Neutral density: Allow larger slit widths without increase in brightness
Yellow: Used for increased patient comfort during the exam, optional filter
Variations of normal on Cornea
Arcus Senilis: Cholesterol deposition in the subepithelial/basement membrane area
Limbal Girdle of Vogt: aging bilateral degeneration
Types of beams
Direct focal illumination: Parallelepiped, Specular reflection, Narrow beam/Optic section Sclerotic scatter Direct retroillumination of iris Indirect retroillumination of retina Conical section
Direct focal illumination: Parallelepiped
45-60 degree angle/displacement, 2 mm beam width, Low to moderate magnification, full beam height, low to moderate illumination.
Corneal epithelial scan, lashes, lid margins (meibomian gland orifices), Conjunctiva (bulbar and palpebral), iris, crystalline lens evaluation
Specular reflection
Angle of illumination= angle of reflection, observation and illumination system have same angle with perpendicular axis to each other, the light reflected from the anterior or posterior corneal surface, beam width
Direct illumination: Narrow Beam/Optical section
45-60 degrees, moderate to high illumination, moderate to high magnification, 0.2-0.3 mm narrowest width possible, Full beam height.
Corneal evaluation: corneal edema, thinning, anterior chamber angle estimation (van herick technique), lens evaluation.
van Herick method (anterior chamber evaluation)
Look at the shadow between cornea and iris. Sensitivity: 87%, Specificity: 84%.
Grade 4: width of chamber interval > width of corneal optic section (1:1 ratio, wide open angle)
Grade 3: width of chamber interval is 1/2 the width of corneal optic section (1:1/2 ratio, unlikely to close)
Grade 2: width of chamber interval 1/4 width of corneal optic section (1:1/4 ratio, narrow angle and capable of closing)
Grade 1: width of chamber interval
Sclerotic scatter
Angle 60 degrees, light directed toward limbus, indirect illumination, beam width of 1 mm, bean height: max, illumination: moderate, magnification: low, viewed at or outside slit lamp.
Highlights subtle findings on cornea, View central corneal haze: historically seen with wear of PMMA contact lenses, not prevalent today.
Direct retroillumination of iris
60 degrees, when reflected of iris or lens, keep focus on cornea, beam width 1-2 mm, beam height: match pupil height to maximum, illumination high, mag low to high, similar to direct illumination, look at structure beside the beam, use iris as background
Indirect retroillumination of retina
0-5 degrees, light in click position, beam width 1-2 mm, beam height: match pupil height to maximum, illumination high, mag from low to high, Light reflects off retina while focusing on structure in front of it.
Conical section
Direct illumination, circular or short square beam, focus light between cornea and iris surface, evaluates anterior chamber for cells or flare, dark room (examiner has to dark adapt), illumination high, mag high
Tear meniscus
Beam angle: 45-60 degrees, beam width 1-2 mm parallelepiped, beam height max, illumination low to moderate, mag 10-16x.
Meniscus is less than 0.5 mm= tear deficiency, 0.5-1 mm= normal.
Tonometry settings
Cobalt blue filter, 45-60 degrees displacement of light source, 10-16x mag, widest and highest beam, highest illumination level
Gonioscopy settings
White light, vertical parallelepiped 1-3 mm wide beam, moderate illumination, 0 degree displacement (in click position), magnification moderate.
Non contact fundus exam settings
White light, enhancement filters: yellow, neutral density, red free filter, O degree displacement, parallelepiped of moderate width and height, low to medium illumination level, low mag: 10x.
Patient positioning issues
Obes or top heavy patients, lower instrument and ask patient to lean forward more. Wheelchair bound patients, watch arm rests, may need assistance with positioning patient.
Binocular indirect ophthalmoscopy
Allows use of both eyes to view fundus yielding stereopsis, light is reflected off retina and converged by condensing lens held in front of patients eye, BIO requires illumination and viewing systems, Bulb/light source is mounted within headset, viewing system of headset is a mirror, oculars, and prisms (prisms allow interpupillary distance to examiner to be set)
View with BIO
Real, arial, inverted and reversed image. Stereoscopic view of fundus, wide field (>40 degrees)
Instrumentation Characteristics
Head mount or spectacle mount (on glasses), Power supply (wired or wireless), digital, ease of use, optics (illumination). Interpupillary distance is optically fixed by the BIO design
Filters on the BIO
Yellow, red-free (green), cobalt blue
BIO condensing lenses
Lower power: +12D to +16D, posterior pole and optic disk evaluation. Medium power: +18D tp +25D. Higher power: +30D to +40D, poor dilation, media opacities. +20D, standard lens, focal length 1/20=0.05m=5cm. Image mag: 2.93x, Field of view= 46 degrees (about 9 disc diameters)
Relationships between lenses
Decrease condensing lens power: increasing mag, decreasing field of view, increasing working distance.
BIO lens characteristics
Aspheric lenses, always hold the most curved surface toward you (position silver ring toward patient), Multi-layered ARC reduces reflections, increases light transmission through the lens.
Clinical indications for pupil dilation
As part of routine examination: older patients, have a higher risk of disease, high risk medications.
Symptomatic patients: +flashes/floaters
Unexplained loss of vision or color perception
Analysis for possibility of retinal disease
Trauma
Post-op cataract patients
Systemic vascular conditions (ex. HTN)
Follow-up on existing retinal disease
Patient education on pupil dilation
Why? To evaluate peripheral fundus (retinal tears/detachments, infections/inflammation, neoplasm, etc.) To evaluate the lens for cataract.
What? Using a lens close to face to magnify the image, bright light to view the retina, if reclining the patient, inform them, do not dim lights too much.
Risk of damage from BIO light
Half-voltage settings: >40 seconds continuously before damage can occur. Retinal disease: lower tolerance to light, less exposure. Possible effect on migraine sufferers/epileptic patients (bright light can precipitate conditions)
Comprehensive medical eye evaluation for adults with no risk factors
65+: every 1-2 years
40-64: Every 2-4 years
30-39: at least twice in these years
20-29: at least once in these years
Definition of at risk adult
Patients with diabetes, hypertension
Family history of ocular disease
Clinical findings that increase their potential risk: working in occupations that are highly demanding visually or are eye hazardous, taking prescription or nonprescription drugs with ocular side effects
Those wearing contact lenses
Those who have had eye surgery
Those with other health concerns or conditions
AOA pediatric recommendations
Birth-24 mos: 6 mos.
2-5yrs: 3 years
6-18 yrs: Before 1st grade and every 2 yrs after.
At risk: as needed before 6, after 6 every years
Definition of at risk child
Prematurity, low birth weight, oxygen at birth, grade 3 or 4 intraventricular hemorrhage, family history of retinoblastoma, congenital cataracts, or metabolic or genetic conditions, infection of mother during pregnancy, difficult or assisted labor, which may be associated with fetal distress or low APGAR scores, high refractive error, strabismus, anisometropia, known or suspected CNS dysfunction
Peripheral retinal landmarks
Nasal Ora Serrata, Temporal Ora Serrata, Vortex vein ampullae, short ciliary nerves, long ciliary nerve, Pars plana, equator
Basic Retinal Structures
Posterior pole and central 30 degrees: Optic disk, macula (fovea), quadrantic branches (SN, ST, IT, IN),
Equator
Imaginary circle through ampullae of vortex veins, represents the anterior and posterior poles, located about 14-15mm from the limbus, vortex composed of choroidal tributaries that number form 4-15 in an eye. Superior vein drains into superior ophthalmic vein, inferior veins drain into inferior ophthalmic vein
Ora Serrata
Junction between the neural retina and ciliary body, anterior most portion of the retina, 2mm wide nasal; 1mm wide temporal, 7mm from nasal limbus; 8mm from temporal limbus, scalloped appearance, serrated more nasally, Ora bays, rounded extensions of pars plana at ora serrata, dentate processes/Ora teeth (retinal extensions between bays), Nasal- oral and dentate processes more prominent, view of ora assures that examiner has viewed all of peripheral retina
Ciliary Body
Pars Plana: broad, flat, pigmented, chocolate-colored band from pars ciliaris to ora serrata, composed of inner nonpigmented epithelium, and outer pigmented epithelium, basal lamina, and layer of blood vessels.
Corona Ciliaria: anterior portion of ciliary body, 2mm wide, contains 60-70 ciliary processes, composed of nonpigmented and pigmented epithelium, stoma, blood vessels, and smooth muscle
Short Posterior Ciliary Nerves
Run perpendicular to ora serrata, located at 6 and 12 o’clock positions of fundus, can have 10-20 nerves per eye in areas other than 3 and 9 o’clock positions, choroidal pigment will surround nerves
Long Posterior Ciliary Nerves
Elongated yellowish projections usually surrounded by pigment located exactly at 3 and 9 o’clock, divide retina horizontally into superior and inferior hemispheres, run from midperiphery to ora serrata, usually accompanied by long posterior ciliary arteries.
Vitreous body
Fills 2/3 of the globe, mostly collagen type 2. Unbranched collagen fibrils make body very elastic, fibrils in decreasing order of density from: vitreous base, posterior vitreous cortex adjacent to retina, anterior cortex/posterior chamber, center of body/adjacent to anterior cortical gel. Also contains hyaluronic acid.
Vitreous cortex
Shell of condensed vitreous that surrounds gel. Two areas: anterior hyaloid face, posterior hyaloid face (composed of dense, tightly packed collagen fibrils, adheres to internal limiting membrane of retina) Firmest attachments at: vitreous base, optic disk, macula, over retinal blood vessels.
Vitreous Base
Vitreoretinal symphysos: extends several mms into vitreous body, straddles ora serrata, virtreous base margins: anterior margin seen as whitish ridge on pars plana, posterior margin is invisible. Vitreous fibrils originate at base, prominent base is hyperpigmented, can be mistaken for lattice degeneration, PVD doesn;t involve vitreous base
Recording Retinal Findings
Normal: flat and intact, 360 degrees OU
Retinal Anomalies: Diagram finding, note size and location. Circumference at equator bigger than that at the ora serrata.
Normal Variations/Benign conditions
Congenital hypertrophy of the RPE (solitary lesion and bear tracks).
Cystic Retinal Tuft (peripheral retinal thinning)
Choroidal Nevus (hyperpigmentation of the choroid)
White with pressure (retinal hypopigmentation or whitening due to scleral indentation
White without pressure (retinal hypopigmentation due to vitreous attachment)
Retinoschisis (neuroretinal layer separation)
CHRPE
congenital hypertrophy of the RPE
- Solitary pigmented lesion, with or without hypopigmented halo
- Bear tracks
- Atypical pigmented lesions
Retinal Tuft
Granular retinal tissue
- Grayish to white lesions in peripheral retina, composed of degenerated retinal tissue and proliferated glial cells
- Usually located between equator and Ora serrata, posterior to ora serrata within vitreous base
- Tend to occur bilaterally
- Cause small vitreous floaters
- Occur in 15% of the population
Choroidal Nevus/Benign choroidal melanoma
Hyperpigmentation of the choroid, may have underlying drusen and other RPE changes, isolated serous sensory retinal detachment may occur near lesion; subretinal neovascularization may occur; onset of pregnancy may cause growth or conversion to malignancy
White without pressure
Area of translucent white to gray retina between equator and ora serrata, more apparent in darkly pigmented races (2.5% Caucasian, 23% Blacks), retina appears thickened may be migratory, incidence increases with age, vitreoretinal traction causes disorganized sensory retina, may be associated with tractional retinal tears.
White with pressure
Optical phenomenon of the retina, retina appears translucent white to gray with scleral indentation, thought to be histologically similar to Ww/oP, thought to have less potential to cause retinal breaks
Retinoschisis
Typical/Flat: splitting of neurosensory retina at outer plexiform layer, in about 0.7% of population. Usually bilateral increased incidence with age, usually asymptomatic but shows scotoma on visual fields test because of separation of photoreceptors from inner retinal connections
Reticular/bullous: splitting of NFL, in 0.95% of population, taut ballooning of tissue, blister. Reticular pattern due to sclerosed scleral vessels. Outer layer shows honeycomb pattern and reduced choroidal detail, cavity thought to be filled with hyaluronic acid
Pavingstone Degeneration
Primary chorioretinal atrophy, aka cobblestone degeneration, thought to be choriocapillaris occulsion with subsequent RPE and retinal tissue loss. 0.1-1.5mm nonpigmented areas between equator and ora serrata. Will often have RPE hyperplasia surround, may see underlying choroidal vessels, aging change with 30-70% bilaterally.
Retinal Holes
Atrophic hole/ retinal break.
-Retinal break without vitreoretinal traction, pinpoint-2DD round red lesion. Occurs in 2-3% of population. Usually between equator and ora. Full thickness break may provide access of liquefied vitreous under sensory retina, less than 7% retinal detachment.
Tractional Hole aka Operculated retinal hole
-result from abnormal vitreoretinal adhesion, round red hole with overlying floating fragment of tissue. Occur between equator and ora. May have associated localized retinal detachment.
Ophthalmic Pharmaceutical Products- Units of availability
Single-dose unit: Once opened, should be used and discarded right away, contains no ingredient to stop microbial growth
Multiple-dose unit: intended for repeated use, contains preservative (chemical with antimicrobial action, rapidly limits growth or kills microorganism, most common preservative in eye drops is BAC.)
Ophth. Pharm. -Formulations
Ophthalmic Solutions/Suspensions:
Aqueous solution containing saline and buffering salts to maintain pH from 5.0-8.0, allows solution to be stored for long time (2 years), many solutions contain small amounts of polymers or viscolizers.
Ophth. Pharm. -Formulations
Ophthalmic Gels
Highly viscous solutions with saline aqueous base and special polymer such as polyacrylic acid, increases contact time on ocular surface
Ophth. Pharm. -Formulations
Ophthalmic Ointments
Non-aqueous preparations, base is oily chemical such as petroleum, paraffin oils, lanolin. Not generally immiscible with water or saline
Ophth. Pharm. -Formulations
Prepared under sterile conditions by law. Prescription must request ophthalmic preparation to be used in or around eye, similar prescriptions are sold OTC, but they are not sterile
Ophthalmic drug delivery
Presented to ocular surface by instillation of eye drop, application of gel or ointment. Preparation is best presented by pulling down the lower eyelid, delivered into lower cul-de-sac. Fate of the eyedrop, coats eye and absorbed into cornea and conjunctiva. About 5% of active drug absorbed. Washed out by aqueous humor through trabecular mechanism. Rest passes down to nasolacrimal duct or wiped from surface.
Drug instillation
Always check: brand name, concentration, expiration date. Document: drug name and concentration, # of drops instilled, time of instillation
Proparacaine Hydrocholoride
Characteristics and Mechanisms
0.5% ophthalmic solution, fast acting topical anesthetic, lasts 10-20 mins. Application by drop instillation or on cotton tipped applicator. Main site of action- nerve cell membrane. Selectively blocks conductivity of sodium ion permeability, inhibits the generation of the action potential, produces changes in phospholipid bilayer of cell membrane that slows or completely blocks nerve signals
Proparacaine Hydrocholoride
Affects, clinical indications
Affects on ocular surface: anesthetizes surface, decreases blink reflex, removes touch sensation, affects are dose dependent.
Clinical indications: applanation tonometry, gonioscopy, short corneal or conjunctival procedures, foreign body removal, punctal plug insertion and removal, cataract extraction, can be instilled prior to mydriatic or cycloplegic drops
Proparacaine Hydrocholoride
Contraindications, Warnings, Safety, Ocular side effects
- Known hypersensitivity
- Prolonged use can cause permanent corneal opacification with visual loss, may delay wound healing, may cause cytotoxicity upon installation
- Unknown affects to fetus or pregnant women, pediatric and geriatric safe.
- Stinging, burning, lacrimation, conjunctival redness, Rarely: intense diffuse epithelial keratitis, epithelium stippling and sloughing
Fluress/Fluorox/Flucaine
Benoxinate Hydrocholride, ocular side effects of burning, stinging, red eye, blurry vision, used to assess integrity of ocular surface, anesthetize eye during tonometry
Sodium Fluorescein Dye
2% solution, used in combination with cobalt blue filter. Emits green color with blue filter. Intensity of fluorescence affected by pH, concentration, other solutes in solution.
Used to assess integrity of ocular surface, stains cells entered and marks damaged areas, conjunctiva stains yellow or orange, cornea stains green, anterior chamber flare appears green. TBUT assessment, measure IOP with tonometer, detection of foreign body, lacrimal patency test. Side effects: stinging, yellow vision
Rose bengal vital dye
Available in 1% impregnated sterile paper strip. Stains a vivid pink or magenta color, significant stinging, staining of cornea, conjuctiva, eyelids. Interacts with impaired mucin layer on epithelial surface. Stains dead and devitalized corneal and conjunctival cells and mucous. Used to evaluate integrity of surface for dry eye evaluation and herpes simplex keratitis. Disadvantages: significant ocular discomfort, difficulty differentiating the red stain and surface imflammation
Lissamine green vital dye
Stains dead and devitalized cells and mucous, stains membrane-damaged epithelial cells and corneal stroma. Non toxic to healthy cells. Stains in bluish green color, available in 1% impregnated sterile paper strip. Less discomfort than Rose bengal, used for same clinical indications.
Fluramene
Combination of fluorescein sodium and lissamine green B solution. Allows assessment of tear film and corneal surface integrity with one drop. Viscosity designed to not disrupt tear film assessment.
Storage of Diagnostic medication
Refrigeration: extends shelf life of most drug. Fluress/ Fluorox if its not used within the month. Increases life of the drug. Decreases the chance of bacterial infection in the bottle
1 cause for Malpractice in Optometry
Misdiagnosis of intraocular disease: retinal detachments, open angle glaucoma, tumors. Majority of claims involving ODs who failed to use diagnostic drops, dilating drops were not used to dilate pupil for internal examination
Before dilating patient…
Check VAs, Check pupils, check IOP, check Angles. Less than grade 2 van Herick angle= risk of angle closure. perform gonioscopy before pupil dilation. If gonio shows half or less of the trabecular meshwork visible in all 4 quadrants–> risk of angle closure
Case history flags
Narrow or closed angle attack: report history of haloes around lights, intermittent eye pain especially going from dim to bright light. Intermittent blur, or ocular redness. Nausea. If patient is at risk and you still dilate. check IOP again post dilation. If IOP increases more than 5mmHg, your patient should be monitored until the IOP is normal again.
Cycloplegia vs. Mydriasis
Cycloplegia: paralysis of the ciliary muscle, reduction of accommodation
Mydriasis: dilation of pupil.
Pharmaceutical agents affect iris dilator muscle, iris sphincter muscle, and ciliary body
Phenylephrine Hydrochloride
Mechanism, Dosage, Side effects
Direct acting sympathomimetic, contraction of the radial dilator muscle of the iris=dilation of pupil. Dosage= 0.12% (for allergies), 2.5%(routine pupil dilation, pre and post ocular surgery), 10% (used to break posterior synechia) Mydriasis only, no cycloplegia.
Side effects: burning, stinging, brow ache, headache, increased tearing, photophobia.
Phenylephrine Hydrochloride
Safety
Use with caution on severe cardiac disease, systemic hyper and hypotension, insulin dependent diabetes, aneurysms, advanced atheriosclerosis, patients taking antidepressants. Vasoconstriction of conjunctival blood vessels, widening of palpebral aperature, uncertain safety in pregnancy and lactation. Dilation up to 6 hours
Tropicamide Hydrochloride
Characteristics
Muscarinic antagonist, blocks the muscarinic receptors in the sphincter eye muscle. 0.5% and 1% ophthalmic solution. Causes mydriases and cycloplegia. Used for dilation for routine examinations, cycloplegic refractions and pre- and post- operative surgery
Tropicamide Hydrochloride
Side effects
Light sensitivity, blurry vision, stinging, unknown safety, dilation up to 6 hours
Cyclopentolate
Parasympatholytic/Antimuscarinic
For cycloplegic refraction, pupil dilation, uveitis treatment (prevents posterior synechiae, reduce pain) Side effects: blurred vision, photophobia, stinging, clumsiness, confusion, GI effects. Uncertain safety in pregnancy and lactation. Length of dilation 6-24 hours.
Stronger Mydriatics/ Cycloplegics
Homatropine (dilation 1-2 days)
Scopalamine (dilation 3-7 days)
Atropine (dilation 7 days)
Atropine
Used for uveitis, dilated eye exam
Homatropine
Uveitis and dilated eye exam
Scopolamine
Break synechiae, pre and post ocular surgery, dilated eye exams, uveitis.
Warnings for Cycloplegias/Mydriatics
History of brain damage/ down’s syndrome/ glaucoma/ spastic paralysis
What happens if you close your patient’s angles?
Symptoms: Pain, blurred vision, colored halos, frontal headache, nausea and vomiting. Signs: acutely increased IOP, corneal microcystic edema, shallow anterior angle, conjunctival injection, fixed, mid-dilated pupil
How do you treat a closed angle?
Topical glaucoma medications, IV/Oral glaucoma medications, Topical steroids, Topical miotics.
Paremyd
Combo of tropicamide and hydroxyamphetamine. Gives good dilation without much loss in accommodation. May not work on brown irises, older patients, and diabetic patients.
Red Cap color
Mydriatics and Cycloplegics (tropicamide)
Pink cap color
Anti-inflammatories (lotemax)
Tan cap color
Antibiotics, antivirals (tobramycin)
Gray cap color
Non-steroidal anti-inflammatories (diclofenec)
Green cap color
Miotics (pilocarpine)
Torquoise cap color
Prostaglandins analogues (latanoprost)
Purple cap color
Andrenergic agonists (brimonidine)
Orange cap color
CAIs (dorzolamide)
Blue/Yellow cap color
Beta blockers (timolol)
