Exotropia

Question 1

What are the main features of distance and non specific exotropia

Answer 1

High levels of illumination is a decompensating factor

Closure of deviating eye in bright light is a common sign

Px are not consistently aware of the eye deviation

Powerful manipulation of accommodation or vergence to control deviation

More evident when Px is day dreaming

History of intermittent exotropia from decompensated phoria

Question 2

How can you investigate intermittent distance exotropia and non-specific exotropia

Answer 2

VA - e

Question 3

How can you investigate intermittent distance exotropia and non-specific exotropia

Answer 3

VA - equal in BE
Controlled Binocualr acuity - measure of VA obtained whilst BSV is maintained

CT -

Convergence - good convergence (can assess deterioration)

Ocular motility - lateral incomitance shown . A decrease in the size of deviation on lateral gaze may be observed

Question 4

How would you manage intermittent distance exotropia and non-specific

Answer 4

Correct Rx

If amblyopia, treat

Monitor - control of exotropia, VA (A decrease in monocular VA suggests strabismus is mostly present ,
NPC - deterioration indicates poor control of near fixation and increased risk of becoming constant ,
Increase in angle of deviation

Question 5

Describe the main features of intermittent near exotropia

Answer 5

Less common than intermittent distance and non-specific variants

Some Px asymptomatic, others complain of asthenopic Sx

Question 6

How can you manage intermittent near exotropia

Answer 6

Correct Rx - may be associated with acquired myopia

Orthoptic exercises - successful in small deviations (<25)

Prism BIN

Combine Prism and orthoptic exercises

Surgery - if deviation is too large to respond to non-surgical treatment

Question 7

What is a constant exotropia

Answer 7

Presence of an exotropia at distance and near under all conditions

Classification based on age of onset and if preceding intermittent deviation.

Decompensated intermittent exotropia or infantile exotropia

Question 8

What are the main features of Decompensated intermittent exotropia

Answer 8

Constant unilateral exotropia with marked suppression

Often equal VA

Excellent BSV following treatment

Presence of strabismic amblyopia implies an early onset of constant and probably unilateral with a poor prognosis for restoration of BSV

Question 9

Describe the main features of Infantile exotropia

Answer 9

Generally resolves by 3 months of age

Large alternating exotropia

Pathology should always be suspected if there is a constant exotropia

Early onset exotropia is also associated with severe crainiofacial abnormality

Question 10

How would you manage constant exotropia

Answer 10

Referral - if identified in early childhood

Correction of Rx

Surgical treatment - Main treatment

Botulinum for those not wanting surgery

Question 11

Describe secondary exptropia

Answer 11

Exotropia resulting from severe vision loss that has the fusion mechanism, usually loss in foveal function

Vision loss usually unilateral

Occurs in some infants with pathological vision loss dating from birth

Retinoblastoma can result in secondary strabismus