Vision Skills Evaluation Flashcards
True or false: it is easy to determine from a patient’s symptoms whether their dysfunction is accommodative or vergence-related in nature.
False; most of the signs and symptoms of both types of dysfunctions are the same.
The Convergence Insufficiency Symptom Survey is a list of 15 symptoms associated with CI. Each symptom is rated on a scale of 0 (never) to 4 (always). A score above _____ indicates symptomatic CI.
score above 16 indicates symptomatic CI
True or false: evaluation of accommodation and vergence skills should always be done through appropriate refractive compensation.
True.
The primary stimulus for vergence is?
Binocular retinal image disparity.
Define: tonic vergence
The underlying level of vergence activity in the absence of a target
Define: fusional vergence
The vergence that occurs in response to binocular target disparity; used to overcome phoric tendencies
Define: accommodative vergence
The vergence that occurs in response to changes in accommodation
Define: proximal vergence
The vergence that occurs due to a mental or psychological awareness of target nearness.
What tests can be used to measure vergence posture?
Cover test, Von Graefe, Maddox rod
What are the expected results for vergence posture at far and at near?
Far: 0-2 exo
Near: 0-7 exo
What is considered a normal AC/A?
3-5^/D
What tests or devices are used to measure associated phoria?
Saladin card, Sheedy disparometer, computerized chart systems at far
In terms of diagnosing vergence anomalies, what does Sheard’s criterion say? For what kind of patients does it work best?
The blur point of the compensating vergence reserve should be at least twice the demand (i.e., a 9^ exo patient should have at least 18^ of PRV range). This works best for exo patients.
In terms of diagnosing vergence anomalies, what does Percival’s criterion say? For what kind of patients does it work best?
The demand line should be in the middle third of the total vergence range (BO blur to BI blur). This works best for eso patients.
The following are methods of measuring vergence amplitude:
NPC
Capobianco method
Prism vergence ranges
What are the minimum values for NPC?
Break at 8cm
Recovery at 11cm
The following are methods of measuring vergence amplitude:
NPC
Capobianco method
Prism vergence ranges
Describe the Capobianco method.
This is a variation on NPC: record the break with a penlight or transilluminator without a red lens, then again with a red lens in front of one eye. A difference of more than 2cm indicates potential symptoms.
What are the OEP minimum expected values for blur/break/recovery for near PRV?
15/21/15
What are the OEP minimum expected values for blur/break/recovery for near NRV?
14/22/18
What are the OEP minimum expected values for blur/break/recovery for far PRV?
7/19/10
What are the OEP minimum expected values for blur/break/recovery for far NRV?
X/9/5
What are the levels of sensory fusion, in binocularity?
Stereopsis (highest)
Superimposition/flat fusion
Simultaneous perception
None (lowest)
Stereopsis can be tested with random dot tests and with lateral disparity tests. Which of these requires bifixation, and which of them can be appreciated even with a small angle strabismus?
Random dot (global stereo): requires bifixation Lateral disparity (local stereo): can have small angle strabismus
