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86 Cards in this Set
- Front
- Back
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Clinical Model of Visual Processing: 3 Major areas of Visual System?
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motor
Sensory Perceptual |
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What kind of deviation is a strabismus?
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manifest deviation
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Prism dioptor amount of deviation that qualifies as a strab?
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deviation of the primary lines of sight of 1 prism D or more
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Are Strabs constant or intermittent?
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Either one. The lines of sight of the 2 eyes are not directed toward same fixation point
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Amblyopia...unilateral or bilateral?
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Usually unilateral...infrequently bilateral
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Is amblyopia correctable by refractive means?
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NO
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Amblyopia is associated with what things?
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form deprivation, strabismus, anisometropia, other ambliogenic refractive errors
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Definition of amblyopia?
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Unilateral, sometimes bilateral...best corrected VA poorer than 20/20 in absence of obvious structural anomalies or ocular dz
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Prevalence of Strabs?
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2-6%
or 5-15 million in US |
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Higher incidence of Strabs found?
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in affected families (23-70%)
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% strab in preschool population?
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3-4%
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Most common visual abnormality in children 6-17?
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strabismus
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Amblyopia prevalence?
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2%
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In the under-20 age group, what causes more vision loss than all trauma and ocular dzs?
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amblyopia
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The VAIS (Visual Acuity Impairment Study) found what to be the leading cause of mono vision loss in 20-70+ age group?
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functional amblyopia
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What is the age limit that amblyopia can be treated?
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there is NO age limit
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According to Birnbaum, is age a significant factor in amblyopia treatment success?
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NO
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Strab/Amblyopia treatment can benfit patients in what ways?
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allow single vision, better cosmesis, stereopsis, increase binoc field, give them a spare eye, increase VA when binoc. (binoc. summation), improved kinesthetic cues, reduce psycho. impact
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4 components of normal binoc. vision?
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anatomical, motor, sensory, integration
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Components of Normal Binoc. Vision: Anatomical examples?
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healthy sensory organs and visual pathways
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Components of Normal Binoc. Vision: Anatomical anomalies?
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Ocular Disease
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Components of Normal Binoc. Vision: Motor examples?
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Accurate mono. fixation of either eye and accurate bifoveal fixation
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Components of Normal Binoc. Vision: Motor anomalies?
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strabismus, nystagmus, vergence dysfunction
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Components of Normal Binoc. Vision: Sensory examples?
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sensory correspondence system organized about the fovea (fovea as the center), similarity of the final perceived ocular images
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Components of Normal Binoc. Vision: Sensory anomalies?
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refractive error, amblyopia, eccentric fixation, accomodative dysfunction
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Components of Normal Binoc. Vision: Integration examples?
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integrated neuromuscular coordination of both intra and extraocular neuromusc. systems and sensory unification of 2 ocular images
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Components of Normal Binoc. Vision: Integration anomalies?
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Aniseikonia, suppression, anomalous correspondence, horror fusionis, central fusion disruption syndrome
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What is eccentric fixation?
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talking about 1 eye by itself...eye points or focuses with new spot other than the fovea. You will measure reduced acuity
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What is anomalous correspondence?
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2 eye situation... fovea of one eye does not correspond with fovea of the other eye (mismatch)
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What is horror fusionis?
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Can't put images together (can't fuse images)
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What is central fusion disruption syndrome?
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brain doesn't want to see images together, images float on top of each other. Seen in head trauma pts.
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What are the components of a Strab/Amblyopia Case History?
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1. CC
2. S/S 3. onset 4. PEH 5. PMH 6. FEH/FMH 7. Goals |
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Strab common signs and symptoms?
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covers one eye in bright sun,
head turns/tilts/tips, blinking or rubbing eyes |
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Intermittent Strabs and large heterophorias often complain of?
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Asthenopia
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Severity of asthenopia may depend on?
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Ability of fusional vergence system
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IF FVS is poor in an intermittent strab, what could happen?
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they may progress to a constant strab (decompensated phoria)
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The greater the frequency of a strab, the higher probabilty of?
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sensory anomalies
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The more sensory anomalies...the fewer the ___?
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symptoms
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Characteristics of a strab without symptoms?
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likely long-standing, has sensory adaptations--suppression, anomalous correspondence, may not recognize symptoms
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In functional amblyopis, it's important to rule out what?
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congenital or pathological causes
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functional amblyopia is usually unilateral or bilateral?
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Mostly UNILATERAL...but can be bilateral rarely-assoc. with high isoametropia or bilateral eccentric fixation
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Strab/Amblyopia:
Congenital period range? |
birth to 6mo-1yr
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Strab/Amblyopia:
Acquired period range? |
greater than 1 yr
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According to Sondi, any XT or ET after what time periods is considered abnormal?
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XT after 6 mo = abnormal
ET after 2 mo = abnormal |
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Which deviation is more predominant during development?
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Exo deviation
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Strab/Amblyopia: Acquired stage's 2 categories?
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1. Early acquired (<5yo)
2. Late acquired (>5yo) |
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Strab/Amblyopia:
Sudden onset could be due to? |
trauma or signal a life-threatening situation
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Which has a better prognosis...intermittent or constant deviations?
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intermittent onset
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Strab/Amblyopia:
Early Onsets-you should think of what kind of adaptations/prognosis? |
sensory adaptations and poor prognosis
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Strab/Amblyopia:
For acute onset, think of what etiology first? |
neurological/pathological
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Parents have better sensitivity or specificity for identifying strabismus?
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specificity...better at determining those who do not have an eye turn (99%)
*only 65% for sensitivity-those who DO have the eye turn *only 50% ability to determine eye turn in kids less than 1 yo |
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incidence of pseudo-esotropia can be as high as?
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50%
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attributes that can confuse paretns and make them suspect esotropia are?
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flat, wide bridges and epicanthal folds. Also developmental period of poor binocular coordination.
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Time between the onset and the treatment becomes more critical when?
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when the onset is earlier
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What is the transmission of strabismus most probably?
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Multifactorial
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Some factors that may be responsible for strabismus are? (4)
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1. high AC/A ratio
2. >1.50 D hyperopia 3. eso/exophoric tendency 4. poor vergence ability |
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situations that prompt early examination of offspring or younger sibling for strabismus?
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1. Either parent has strabismus
2. older sibling has strab 3. FEH of strab, even if parent and sibling normal 4. Normal parents but between them = low vergence ability, and >1.50 D hyperopia |
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Risk factors for exotropia/esotropia? (4)
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1. low birth weight
2. maternal cigarette smoking 3. increased risk for ESOtropia with increased maternal age 4. assoc. with neurogenic abnormalities, seizure states, CNS and skeletal system conditions |
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What is an important etiological factor in strabismus and amblyopia?
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refractive status
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50% of all amblyopia is caused by?
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anisometropia
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According to Chimonidou, 72% of children w/strabismus had?
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Abnormal refractions
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2 significant attributes related to developing ESOtropia and amblyopia?
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1. >2.00 D hyperopia (increases strain on accom system)
2. >1.00 D anisometropia, any meridian |
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As you scope off axis, what happens to astigmatism vs. spherical power?
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astigmatism increases...spherical power decreases
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How does increased accomodation by the pt. affect (-) vs. (+)?
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Increased accom. = artificially increases (-) and decreases (+)
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When doing ret, if you see a sudden shift from "with" to "against" motion, what is happening?
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the patient is accomodating
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when should you consider out of phoropter refraction?
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children and all deviations >15 pd
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Noncycloplegic Static Ret is what kind of procedure?
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ON-AXIS initial screening procedure
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For Noncycloplegic Static Ret, what do you do with the prism? (mainly ET and vertical problems)
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hold the correcting prism in front of the FIXATING eye. (eye looking at the E)--use neutralizing prism
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Another name for Near Ret Method is?
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Mohindra
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mohindra working distance is?
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50 cm
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What is the method for Mohindra?
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1. patient in chair or lap
2. 50cm WD 3. Room lights OUT 4. Pt fixates on Ret and monitor corneal reflex to make sure "on-axis" 5. Occlude one eye 6. Neutralize primary meridians 7. Subtract 1.25 from sph value |
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To agree with cyclop. ret, Saunders suggests what changes for children and infants?
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Children = subtract 1.00 D
Infants = subtract 0.75 D |
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How does Noncycloplegic Static Ret affect Hyperopia?
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it slightly underestimates Hyperopia
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If you have poor confidence in Noncycloplegic Static Ret what should be done instead?
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cycloplegic refraction
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What drug is better suited for a cycloplegic refraction?
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cyclopentolate
*NOT tropicamide = short duration, poor at eliminating high accom tonus of childhood |
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Cyclopentolate dosage?
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<1 yo = 0.5% soln 2 gtts (1 gtt wait 5 min, add 1gtt)
>1 yo = same gtts but use 1% soln |
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Cyclopentolate response for nydriasis and cycloplege?
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Mydriasis = within 30 min
Cycloplegia max = 30-45 min |
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Cyclopentolate duration for mydriasis and cycloplege?
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Mydriasis = 24 hrs
cycloplege = 8-24 hrs |
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Cyclopentolate toxicity symptoms?
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restlessness, aimless wandering, irrelevent talking, hallucinations, memory loss, faulty orientation to time/place
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Atropine Dosage?
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<1yr = 0.5% soln/ung BID x 3 days prior to exam
>1 yr = same except use 1% |
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Atropine Response for mydriasis and cycloplege?
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Mydriasis = within 30-40min
Cycloplege = within 1 hr, max 3-6 hrs |
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Atropine duration for mydriasis and cycloplege?
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Mydriasis = as long as 12 days
Cycloplege = 10-18 days |
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Atropine toxicity symptoms?
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dryness of mouth ans skin, flushing of face, fever, tachycardia, irritability or delirium
*TX = physostigmine 0.25mg SubCut inj repeated q 15min until symptoms decrease |
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How do you determine adequacy of cycloplegia?
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NPA = < 2D accomodative amplitude
Dynamic ret = +2.00 D lag or greater Use single line of threshold Snellen @ distance. Add -0.75, if this reduces VA, then cycloplegia is adequate |
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Is pupil size an indicator of adequate cycloplegia?
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NO
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In cycloplegic refraction, how do you scope? How do you do it with an eye turn?
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Still need to scope "on-axis"
Use prism or pt looks at ret light monocularly (Subtract WD!) |
