The Exotropias

Exotropia vs. Esotropia

- age of onset (duration)

- type of onset

- angle size

- frequency

- perceptual (sensory) adaptations

+ anomalous retinal correspondence

~ sensory etiology

~ motor etiology

+ suppression

+ amblyopia

- accommodative component

- prognosis

CHARACTERISTICS OF COMITANT EXOTROPIA

- onset, birth to 8 years; usually gradual

- frequency; usually intermittent

- refractive error; nothing outstanding

- retinal correspondence; NRC, co-variation with ARC

- amblyopia; in about 5% of cases

- AC/A ratio; normal or low

- symptoms; photophobia, squinting

- prognosis; usually good

CLASSIFICATION OF COMITANT EXOTROPIA

- fixation distance

+ convergence insufficiency

+ divergence excess

+ basic exotropia

- frequency

+ intermittent

+ constant

- age of onset

+ congenital

+ infantile

+ childhood

+ adult

INTERMITTENT EXOTROPIA OF THE DIVERGENCE EXCESS TYPE

1. distance angle > near angle

2. deviation is intermittent

3. angle of deviation increases with fixation distance

4. weak accommodative skills

5. high AC/A ratio?

- near-far AC/A calculation

- gradient AC/A determination

6. pseudo or simulated divergence excess

- prolonged occlusion

- + 3.00 gradient

- e.g.

distance CT: 30 pd exotropia

near CT: 10 pd exotropia near

CT after occlusion: 25 pd exotropia

conclusion: pseudodivergence excess

really a basic exotropia

7. infrequent diplopia

- suppression

- anomalous retinal correspondence

8. panoramic viewing

MANAGEMENT OF INTERMITTENT EXOTROPIA OF THE DIVERGENCE EXCESS TYPE

1. refractive correction

- bifocal correction (for accommodative dysfunction)

- bifocal correction (for near point esophoria)

- reduce hyperopic correction

- over minus correction

+ Rx that bifocal

2. occlusion

3. prism

4. vision therapy

5. surgery

6. combined therapy