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31 Cards in this Set

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Components of Accommodation:

what is Reflex Accommodation
1. automatic focusing of the eye in order to obtain clear retinal image
2. occurs in response to retinal blur
3. **Largest most important component in accommodation under monocular and binocular conditions**
Components of Accommodation

what is Vergence Accommodation
1. Accommodation that is induced by the vergence system
2. gives rise to the CA/A Ratio
3. **Second Major Component in Accommodation**
Components of Accommodation

what is Proximal Accommodation
1. accommodation caused by the knowledge of nearness of obj
2. can be induced by obj within a distance of 3m
3. contributes to 4-10% of the total accommodative response, under normal binocular viewing conditions
4. stimulate by perceptual cues
5. no retinal feedback components
Components of Accommodation

what is Tonic Accommodation
1. accommodation present by virtue of just being alive
2. NO STIMULUS
3. baseline neural innervation from midbrain
4. measured in complete darkness with nothing to stimulate proximal accommodation
5. ~1.00D in adults (range: 0-2D)
what can be said about a patient that FAILS TO CLEAR MINUS in BAF
1. problem STIMULATING accommodative system (AI)
2. minus causes an increase in ESOPHORIA which requires even more NRV to keep the target single (CE)
what can be said about a patient that FAILS TO CLEAR PLUS in BAF
1. problem RELAXING accommodative system (AE)
2. plus causes an increase in EXOPHORIA which requires even more PRF to keep the target single (CI)
what is the formula for expected values of accommodation
Minimum= 15 - (1/4)(AGE)

Average= 18- (1/3)(AGE)
what can cause accommodative fatigue? (3)
1. uncorrected hyperopia or astigmatism
2. anisometropia
3. myopes who read with their Rx

crucial to consider the pts refractive status when examining the accommodative system
how do you test amplitudes of accommodation?

how do they compare with each other in terms of estimation
must have the patient fully corrected (false values)

Push Up:
- overestimates amp by 2D

Pull Away:
- PREFERRED METHOD
- better certainty of obtaining first sustained blur
- measure target at spectacle plane

Minus Lens to Blur
-lower values than PULL AWAY
what is the preferred method of determining the ACCOMMODATIVE POSTURE on a NON PRESBYOPE, especially in kids
1. MEM
2. Objective testing
at what distance is MEM performed at?
- Harmon Distance
- elbow to middle knuckle
how long should you hold a lens in front of a patients eye when doing MEM
1. Quickly place lens over the eye you are examining to see neutrality
2. just long enough to see the REFLEX
3. holding the lens for too long will start to affect the patients accommodative system
what conditions correlate with a LAG of accommodation?

LEAD??
LAG (plus value):
1. Accommodative Insufficiency
2. Convergence Excess

LEAD (minus value):
1. Accommodative Excess
2. Convergence Insufficiency
what is the norm for MEM
+0.25 to +0.75
what is the difference between AI and presbyopia
Presbyopia has...
1. age 40+ years old
2. amp is not sufficient to sustain clear/comfortable vision at near
3. AMP IS NORMAL FOR AGE
how can AI manifest as ESO or EXO
manifest ESO:
1. at near if convergence is overestimated to encourage accommodation

manifest EXO:
1. at near if accommodation does not stimulate convergence enough
Accommodative Insufficiency:
1. amps
2. MAF or BAF
3. MEM or BCC
4. PRA
1. amplitudes less than 2D than expected in age
2. MAF/BAF fails through MINUS
3. MEM/BCC high LAG
4. reduced PRA
how can you detected ILL SUSTAINED ACCOMMODATION
AMPLITUDES MUST BE REPEATED

- fatigue with after 5-10 times
- prequel to AI
- same measurements as AI
what is accommodative infacility?

what test COULD be abnormal
1. accommodation slow in making change from distance to near

could be abnormal:
1. reduced MAF/BAF
2. reduced NRA/PRA
3. low BO/BI findings at NEAR
what are the findings of accommodative excess:
1. MAF/BAF
2. MEM/BCC
3. NRA
1. fails through PLUS on MAF/BAF
2. LEAD on MEM/BCC
3. LOW NRA
how does AE manifest EXO or ESO
EXO:
- stimulation of accommodation (CA/A link) at near to overcome EXO POSTURE if the primary problem is the exo posture at near

ESO:
- with accommodation the #1 problem, over accommodation (AC/A link) leads to an overall ESO posture at near
what are some signs that a patient will accept PLUS LENS
1. NRA higher than PRA by +0.50 or more
2. MEM greater than +0.75
are are some exam values that suggest the need for plus at near
1. LOW AMPS
2. ESO at near
3. LOW PRA
4. HIGH LAG on MEM
5. asymmetry in NRA/PRA (greater NRA relative to PRA)
6. new myopic Rx showing ESOPHORIA
it terms of emphasis what should you consider in accommodative VT
amplitudes BEFORE speed of response
what is the objective of lens sorting therapy
1. monocular
2. develops awareness of stimulating and relaxing accommodation
3. teaches voluntary control over accommodation
4. can demonstrate to patient size and distance changes with the lenses
what is the FINAL STEP of lenses sorting (monocular)
to have the patient sort the lenses from what makes them feel more relaxed, to what make them feel more strained
what are the MONOCULAR tests you can do in VT for ACCOMMODATION
1. develop rapport
2. lens sorting
3. N/F hart chart
4. MAR

*amplitudes before reaction time
*emphasize the feeling of stimulation then relaxation
what are the BIOCULAR tests you can do in VT for ACCOMMODATION
1. red/red rock: starts with +/- 1.00 combo
2. biocular loose lens rock

this step may be skipped depending on level of suppression
what are the BINOCULAR tests you can do in VT for ACCOMMODATION
1. binocular accommodative rock
2. binocular N/F hart chart
what is pathological diplopia
1. diplopia of a fixated target
2. occurs in strabismic patients that have little or no suppression
3. image of the non-fixating eye falls on non macular point
what is physiological diplopia
1. occurs in normal binocular vision
2. non fixated objects stimulating non corresponding points are diplopic
3, suppression of diplopic objects are psychological