Heterophoria/Convergence Insufficiency Flashcards
What is the definition of heterophoria?
When the eyes are dissociated, a latent squint becomes manifest. Eyes are straight when both open.
What is convergence excess?
Deviation angle is larger at near
What is divergence weakness?
Deviation is larger at distance
What is non-specific esophoria?
No significant difference between deviation size at different distances
What is convergence weakness?
Larger deviation angle at near
What is divergence excess?
Larger deviation at distance
What is non-specific exophoria?
No significant difference of deviation size between distance and near
What are some common aetiologies for vertical deviations?
Congenital vertical muscle palsies
Thyroid eye disease
What does it mean if a phoria is compensated?
Px has enough fusional reserves to maintain BSV without lots of effort
What does it mean if a phoria is decompensating?
Lots of effort is being made to maintain BSV.
Sometimes controlled, but not all the time.
Likely eye strain and headaches, blurred vision, intermittent diplopia.
What does it mean if a phoria is decompensated?
Completely broken down - no control over phoria and unable to fuse.
Has turned into tropia.
What are some causes of decompensation?
Uncorrected or undercorrected RE (accomm needed so FRs struggle)
Poorly fitting specs cause poor image quality
Aniseikonia (can’t cope if new, e.g. cat op)
Poor GH (reduced FRs)
Head trauma
Drugs
Change in visual demands
