Convergence Anomolies Flashcards
What is convergence
- convergence is a vergence movement movement that allows the visual axis to stay directed towards a near target
Types of convergence anomaly
- convergence insufficiency
- convergence paralysis
- convergence spasm
What is convergence insufficiency, and types
- NPC is less than 10cm
- convergence can only be maintained a this distance
- can be primary or secondary
- primary has no other causes for convergence insufficiency are present, including heterophoria
Aetiology of primary convergence insufficiency
Pre-disposing factors
- large interpupilliary distance
- large periods of tie only using distance fixation
Precipitating factors
- fatigue from long periods of close work with/without poor lighting
- illness
- age
- medication/ recreational drugs
- pregnancy
What causes secondary convergence insufficiency
- intermittent near exotropia
- convergence weakness exoptropia
- neurological condition
- whiplash after accident
- thyroid eye disease
- Latrogenic medial rectus weakness after surgery
Common symptoms of convergence insufficiency
- difficulty with close work
- intermittent diplopia during near work
- blurred vision during near work
- frontal headache
- eye strain
- difficulty concentrating
- movement of print
Investigation of CI
- Case history
- distance and near Vision
- cover test and angle of deviation
- assessment of convergence
- accommodation of convergence
- accommodation
- fusional amplitude
How to assess convergence
- accurate assessment of convergence can be achieved by using th eRAF rule
- allows for specific measurement of convergence and accommodation
How to record RAF result
- record result for all 3 measures
- if effor was exerted
- if convergence was broken and which eye deviated
Treatment of convergence insufficiency
- correction of refractive error
- orthoptic excerises
- smooth and jump convergence
- pen to nose = smooth
- dot card = jump
- base in prisms
- correct near exotropia
What is convergence paralysis
- ability to converge is lost
- any be primary or secondary
What is primary convergence paralysis
- no previous history
- investigation rules out other secondary causes
What is secondary convergence paralysis
- head trauma
- neurological cause
Clinical features of convergence paralysis
- diplopia for all distances
- ocular motility is normal in primary convergence paralysis
- accommodation may or may not be impacted
Management of convergence paralysis
- once secondary convergence palsy is ruled out, underlying cause is investigated
