Bv Lec 5 Flashcards
What is convergence insufficiency
Exotropia or high exophoria in near vision in association with a relatively orthophoric condition at distance, and a relatively low increase in convergence associated with an increase in accomodation (low AC/A)
Symptoms of convergence insufficiency
Visual discomfort
-ocular fatigue, headaches, asthenopia
Unstable vergence/accommodation system
-intermittent blur at near, diplopia at near, squinting
No desire to do close work
-affects academic performance and productivity in work force
Pathogenesis of convergence insufficiency
Heredity
-large exo
Sensory factors
-any disruptions with sensory integration reduces PFV e.g uncorrected RX, bad lighting
Motor factors
- low stim calc AC/A
- low response calc AC/A
- low gradient AC/A
- low PFV
- low NPC
Treatment for convergence insufficiency
Base in prisms
Increasing accommodation through minus lenses or accommodative training
PFV training
What is divergence excess
An intermittent exoT of DE type where there is exoT on distance CT, exoP or exoT on near CT, distance deviation at 6m is greater than near deviation by 10 prisms or more
Symptoms of divergence excess
Cosmesis (main)
One eye closes in bright light
Occasional loss of stereopsis e.g in sports or parking
Pathogenesis of Divergence excess
Heredity -common and appears in offspring early
Sensory factors - direct relationship with unequal ocular images and prevalence of DE
Motor factors - appears to be over divergence and NOT a relaxation of convergence.
Therapy of divergence excess
Correct Rx
Monocular motor skills training (tracking) - impt voluntary vergence
Anti suppression training
Accommodative facility training
Fixation training e.g clockwatch exercise so can focus/relax as well as converge/diverge same time
Fusional vergence training - motor fusion exercises with target with depth puts motor and sensory fusion training together
Sensory integration training
Difference between true and pseudo convergence insufficiency
True - low PFV but normal accom so px overaccommodates to increase vergence. Stimstim
How to use NPC to differentiate a tropia and Phoria in convergence insufficiency
Closer than NPC = constant exoT
At NPC = intermittent exoT
Slightly out than NPC = exoP with slow recovery +doesn’t meet Sheards
Distance = latentExoP + sufficient motor fusion
First 4 Characteristics of convergence insufficiency
1) insig latent dev@distance BUT sig exo@near
2) stim&resp ACA low
3) PFV reduced/absent @near
4) can’t converge to normal NPC
Last 4 characteristics of convergence insufficiency
1) stereopsis threshold good outside NPC but absent inside
2) reduced NRA=less BPA due to low PFV
3) if suppression exists it’s intermittent and diplopia intermittent when supp absent
4) classifies near dev AMOUNT based on distance dev
How to test for monofixational esophoria
Bagolini lenses
Cover test (H and S)
4prism loose prism test
What’s treatment for suppression/describe anti suppression training
Repeatedly show suppression like environment e.g Chang contrast so worse for good eye and forces bad eye to work
What’s training for intermittent diplopia
Refixation training - voluntary vergence training or converting an intermittent strabismus into a phoria
