The Squint Club, a group of ophthalmologists with strabismus expertise, meets once a year to discuss difficult and unique clinical cases, new ideas about treatment and unique notions of pathophysiology regarding various disorders of ocular motor alignment. It was therefore surprising and noteworthy when several years ago at this meeting the late Arthur Rosenbaum presented a paper in which he stated that he thought the most perplexing and difficult form of strabismus in his practice was intermittent exotropia. Many in the audience were surprised by this statement. An unstated concern was the thought that intermittent exotropia might be too simple a condition for this august body to discuss. After all, intermittent exotropia appears to be an uncomplicated form of strabismus that ought to be easily treated with an expectation of consistent and excellent outcomes since it is characterised by:

1. Occurrence in developmentally and neurologically normal children (unlike the case of infantile exotropia).1

2. Initial normal binocular development at both distance and near fixation.

3. A relatively low incidence of amblyopia which when it does occur is mild.2

4. Occurrence of dissociated strabismus is less common than in infantile forms of strabismus.3

5. Surgery appears to be the treatment of choice for all but the smallest deviations.4

Rosenbaum, however, convincingly made his point by emphasising that there was much that remained enigmatic about intermittent exotropia. These enigmas are not merely of academic interest, he argued, but central to the problems of managing children with intermittent exotropia. He highlighted a number of his concerns regarding intermittent exotropia:

1. The natural history of untreated intermittent exotropia remains incompletely defined.5

2. Even the widely accepted notion that in most cases it deteriorates over time has been challenged.6

3. Precise clinical indications for …