Exam 1 Material Flashcards
What are the 3 requirements for binocular vision?
- Corrected refractive error
- Motor fusion
- Sensory fusion
What drop is used for a “damp” refraction?
Tropicamide
What drop is used for a “wet” refraction?
Cycloplegic drop
What is mohindra?
Near point retinoscopy used for infants
Monocular, in a dark room
Infant looks at light
1.25 D working distance
What kind of blur would a moderate hyperope experience?
Near point blur
What kind of blur would a moderate myope experience?
Distance blur
What is heterophoria?
Natural deviated resting position of dissociated eyes
What is fusional vergence demand?
Amount of motor fusion needed to compensate for phoria that is present
What type of convergence errors are esophoria and exophoria?
ESOphoria - OVER convergence when dissociated
EXOphoria - UNDER convergence when dissociated
What type of fusional vergence compensates for ESOphoria?
NFV
Negative Fusional Vergence
What type of fusional vergence compensates for EXOphoria?
PFV
Positive Fusional Vergence
What is the term for eyes that have normal alignment under dissociated conditions?
Orthophoria
What 3 symptoms does poor motor fusion create?
- Diplopia
- Fatigue
- Blur
In terms of accommodation, what helps with an eso deviation?
Relaxing accommodation
Plus lenses
In terms of accommodation, what helps with an EXO deviation?
Stimulating accommodation
Minus lenses
What allows for the foundation of stereopsis?
Two eyes with two different visual directions
What are the Big 6 of the binocular exam?
- Refractive Error
- Phoria
- Accommodation
- Vergence
- Oculomotor skills
- Fusion
What equipment can be used to screen and check if the patients tentative Rx is appropriate?
+/- 2.00D Flipper
What is the scale that gives a functional number for cover test, rather than just the magnitude of deviation?
Mayo Control Scale for XT
What is the expected AC/A ratio if near is relatively more EXO (>5 prism diopters) than distance?
Low or high?
Low AC/A
This is me
What is the expected AC/A ratio if near is relatively more ESO (>5 prism diopters) than distance?
Low or high?
High AC/A
What is the difference between comitant and non-comitant phoria?
Comitant: Constant phoria in all positions of gaze
Non-Comitant: Phoria changes with position of gaze
If a patient is more ESO at near while performing kinetic cover test, is their expected AC/A high or low?
High AC/A
Is the “Push-up” or “Pull-away” test better for patients that don’t understand the concept of blur?
“Pull-away” test
Instruct patient to say when line is clear
What is the MINIMUM expected accommodative amplitude of a patient as described by Hoffsteter’s formula?
15 minus (0.25 x patient age) Example: 20 year old 15 - (0.25x20) = 15-5 = 10D
At what distance should MEM retinoscopy be performed?
At reading distance for the patient
What does it mean to have accommodative lag?
Patient is using LESS accommodation than necessary
What does it mean to have accommodative lead?
Patient is using MORE accommodation than necessary
If a patient views the HORIZONTAL lines as darker in Binocular Cross Cylinder testing:
What is happening with accommodation?
What corrective lenses should be used?
Accommodative LAG
Plus lenses
If a patient views the VERTICAL lines as darker in Binocular Cross Cylinder testing:
What is happening with accommodation?
What corrective lenses should be used?
Accommodative LEAD
Minus lenses
Is accommodative LAG or accommodative LEAD the expected normal value?
Accommodative LAG
What should be used as a suppression check for accommodative facility testing?
Red/Green Bar Readers
How long should accommodative facility be tested?
One minute
What is an example of a “smooth” vergence range measurement?
Risley prism
What is an example of a “step” vergence range measurement?
Prism bar
What are 3 examples of oculomotor skills to test?
- Fixation
- Saccades
- Pursuits
What does Worth 4 dot testing measure?
Presence and/or size of scotoma
What is a requirement for a global stereopsis test?
Must be bifoveal
What is the absence of fusion?
Suppression
No depth perception
What is an example of a patient where prescribing the full Rx would negatively impact posture?
Uncorrected hyperope w/ significant exo posture
What are 2 important considerations for performing static retinoscopy on pediatric patients?
- Bracket
2. Be fast and precise
Mohindra is typically performed monocularly. What is an example of where it would be performed binocularly?
Infants
What is a common error of autorefractor readings?
Over-minusing of patients
When is an autorefractor useful for rechecking a prescription?
After cycloplegic drops
When is a handheld autorefractor useful?
Wheelchair bound patients
Young or small patients
Why is a cycloplegic refraction used?
To control accommodation
What are the 3 most common cycloplegic agents?
- Atropine
- Cyclopentolate
- Tropicamide
What is the most potent cycloplegic agent and how long does it last?
Atropine
1 week
How long do the effects of cyclopentolate last?
24 hours
For about how long do the effects of tropicamide last?
4-6 hours
How much residual accommodation is left when using tropicamide?
About 5 diopters
How much residual accommodation is left when using cyclopentolate?
0.75 diopters
What type of drug is cyclopentolate and what is its action?
Anticholinergic
Inhibits iris sphincter and ciliary muscle
What is pseudomyopia caused by?
Spasm of the ciliary muscle
What should dosage of cyclopentolate be for patients under 1 year old?
Over 1 year old?
Under 1 - 0.5% cyclopentolate
Over 1 - 1.0% cyclopentolate - 2 drops 5 mins apart
What are some adverse reactions to cyclopentolate to be aware of?
Blur, photophobia (expected)
Increased IOP if angle closes
Seizures, behavior change, cardiac problems
What are 5 types of patients to monitor closely if cyclopentolate is used?
- New patient
- Previous adverse reaction
- Frail cardiovascular system
- Compromised CNS (Down’s, TBI, etc…)
- Narrow anterior chamber angle
What does a binocular refraction allow for greater control of?
Accommodation
Also, more accurate endpoint for cylinder axis
What are 3 techniques of refraction that do not require blur balance as an additional step?
- Septums (infinity balance)
- Polarized slides (vectographic)
- Fogging (Humphriss)
What is true of most hyperopic infants?
They will stay hyperopic, but the extent will lessen
What is true of most myopic infants?
They will become hyperopic and then proceed into myopic during the school age years
Are hyperopes or myopes at higher risk of developing amblyopia?
Hyperopes
When should you prescribe lenses for hyperopes?
Greater than +2.00D at any age
What should you prescribe lenses for myopes?
Greater than -3.00D for 1-3 year olds
Greater than -1.00D for all over 3 years old
When should you prescribe lenses for astigmats?
Greater than -1.25D of cyl
What is the goal of case analysis?
Evaluate all exam data to make a diagnosis
What is very important for all BV patients?
Management of symptoms
What are the 3 steps of the integrative analysis approach?
- Compare tests to tables of expected findings
- Group findings that deviate from expected results
- Identify the syndrome
What specific norms are we using for this class?
Morgan’s norms
What syndromes are associated with LOW AC/A?
Insufficiencies
convergence and divergence
What syndromes are associated with HIGH AC/A?
Excess
convergence and divergence
What is the near triad?
Convergence
Accommodation
Miosis
What is the formula for calculated AC/A?
PD + (NFD)(Hn-Hf) NFD = Near Fixation Distance in meters Hn = Near Phoria Hf = Distance Phoria All eso is plus All exo is minus
Where is gradient AC/A performed?
At near
What is CA/C ratio?
Convergence Accommodation/ Convergence
What are direct tests for PFV and NFV?
Smooth and step BO and BI ranges
What will all direct tests of accommodation be?
Monocular
Are convergence problems near or distance problems?
NEAR problems
Are divergence problems near or distance problems?
DISTANCE problems
What is the definition of fixation disparity?
Small angle of misalignment of the eyes under binocular conditions
What is required to be occurring for fixation disparity to be present?
Fusion
In order for fusion to be present, where must the amount of inaccuracy be within?
Panum’s Fusional Area
Where in Panum’s Fusional Area are patients more likely to experience symptoms with fixation disparity?
Near the edges of Panum’s Fusional Area
Results from larger magnitude fixation disparity
What type of fixation disparity is a patient with esophoria likely to have?
Eso fixation disparity
What is a ‘slang’ term for fixation disparity as related to the visual system?
“ready position”
What are 5 examples of methods/equipment that measure fixation disparity?
- Mallet Box
- Disparometer
- Borish Card
- Wesson Card
- Saladin Card
What is a very precise method of measuring fixation disparity?
Disparometer
What 3 things must all measuring methods of fixation disparity provide?
- Binocular fusion lock
- Two monocular nonius lines
- Natural conditions (not dissociated)
What does the x-axis of a fixation disparity curve measure?
Prism amount in prism diopters
What does the y-axis of a fixation disparity curve measure?
Magnitude of fixation disparity in arc minutes
What is the x-intercept of a fixation disparity curve and what are its units?
Associated phoria
prism diopters
What is the y-intercept of a fixation disparity curve and what are its units?
Magnitude of fixation disparity
arc minutes
What is significant about the associated phoria?
The amount of prism diopters needed to reduce the fixation disparity to ZERO
Where is the slope for a fixation disparity curve observed?
Between 3 BO and 3 BI
What does a steeply sloped fixation disparity curve signal?
Poor ability to adapt to prism
What does a fixation disparity curve with a flat slope signal?
Good ability to adapt to prism
What type of curve do most patients show with a fixation disparity curve?
Type 1
What does a type 2 curve look like and what does it signify?
Looks like an L
Poor adaptation to BI prism
Esophoria usually present
What does a type 3 curve look like and what does it signify?
Looks like a 7
Poor adaptation to BO prism
Exophoria usually present
What does a type 4 curve look like and what does it signify?
Looks like a Z
Poor sensory or motor fusion
What 2 things are a fixation disparity curve useful for?
- May help uncover a BV problem not found with other tests (symptomatic patient without signs)
- Monitoring vision therapy progress
What are the 4 steps in the order of evaluation?
- Comprehensive Eye Exam
- Binocular Vision Follow Up
- Treatment Decision
- Follow Up/ Monitor
What is the main goal for treatment of accommodative and non-strabismic disorders?
Overcoming symptoms
What are the 2 main BV symptom surveys?
- Convergence Insufficiency Symptom Survey
2. COVD QOL Survey
What is the purpose of a symptom survey?
Can be used to show measurable decreases in symptoms
What is extremely important in the prevention of amblyopia or strabismus?
Early detection
In order from least invasive to most invasive, what are the 6 parts of the sequential management approach for amblyopia?
- Optical correction of ametropia
- Added lenses
- Prism
- Occlusion
- Vision therapy
- Surgery
Is there an age limit on treatment of amblyopia?
NO
Example - Stereo Sue
When does rapid emmetropization occur?
Infancy
very noticeable between 3 and 9 months
When is it always important to prescribe a myopic Rx?
When patient has significant refractive error
When patient is an exotrope (especially when intermittent)
What should you be careful with when prescribing plus lenses?
Don’t want to make the patient exo
What is an important consideration when prescribing astigmatic correction?
Astigmatism should be deemed stable before prescribing for it
During what span of life are larger amounts of astigmatism common?
Less than 3 years old
What types of astigmatism are more stable?
With the Rule
Oblique
What amount of anisometropia presents a large risk for amblyopia?
Greater than 3 diopters at 1 year old
Where should the bifocal line be measured for on a 3-5 year old patient?
Pupil center
Where should the bifocal line be measured for on a 6-7 year old patient?
Lower pupil
For any patient older than 8 years of age, where should the bifocal line be measured?
Lower lid margin
What amount of prism should you prescribe for any given patient?
The least amount needed to come to the desired result.
How does Sheard suggest the Compensational Fusional Vergence should relate to the phoria of a patient?
CFV should be twice the phoria
What is the formula for Sheard’s Criterion?
Prism needed = (2/3 phoria) - (1/3 CFV)
How should prescribed prism be split between eyes?
Half and half
Example 4 BI total would be 2 BI OD and 2 BI OS
For what type of phoria is the 1:1 rule mostly used for?
ESOphoria
What does the 1:1 Rule state?
Recovery is greater than or equal to the phoria
or the patient may have symptoms
What amount of vertical prism is clinically significant?
0.50 prism diopters
Should prescribed prism allow for fusion all the time?
Should allow for fusion MOST of the time
Remember, Rx the least amount possible for relief of symptoms
How long should patching occur in cases of moderate amblyopia?
2 hours a day
How long should patching occur in cases of severe amblyopia?
6 hours a day
What is the long term goal of vision therapy?
To develop normal: Sensory fusion Motor fusion Accommodative skills Oculomotor control
What amount of horizontal deviation may warrant surgical intervention?
Greater than 30 prism diopters
What is the Relative Point Value with respect to add determination?
The difference in dioptric power from the patient’s BVA (therefore BVA=0)
What is the formula for balancing the NRA and PRA to determine the add for a patient?
(NRA+PRA)/2 + RPV
Should NRA be a positive or negative value?
Positive
Should PRA be a positive or negative value?
Negative
How does a high AC/A impact PRA?
High AC/A lowers the potential PRA with all else the same
When training BI values, what vergence direction is being trained?
Divergence
When training BO values, what vergence direction is being trained?
Convergence
What kind of lenses make divergence more difficult?
Minus lenses
What kind of lenses make convergence more difficult?
Plus lenses
What is the normal AC/A ratio based on Morgan’s Norms?
4/1
