Clinical and surgical risk factors for consecutive exotropia

Consecutive exotropia is one of the complications of esotropia surgery. Its prevalence is estimated at 4%-27%. The aim of this study was to identify the risk factors for consecutive exotropia in the aftermath of surgical treatment of esotropia.

Seventy-four patients examined in our strabismus consultation for a consecutive exotropia from January 2010 to June 2016 were retrospectively included. The age of onset of esotropia, the presence of amblyopia, the age of esotropia surgery and chosen procedure, the refractive errors, the anomalies of ocular motility, the age of onset of the consecutive exotropia and its angle of deviation were reported. Statistical analyses were performed with Student's test and Fisher's exact test.

Esotropia occurred in 65% of cases before the age of 1 year, was associated with amblyopia in 51%, hyperopia in 55% or anisometropia in 31%. Surgery was performed before the age of 6 years for 55% of the patients and involved for 52% the both medial recti. The angle of deviation of consecutive exotropia was ≤20 prism dioptres (PD) in 39%, 21-40 PD in 39% and ≥ 40 PD in 22%, related to amblyopia (p = 0.028), and to high hypermetropia (p = 0.05).

Amblyopia and hyperopia were the most important risk factors of consecutive exotropia in our series. Early onset esotropia, stereopsis abnormalities, anisometropia, oblique dysfunction, convergence insufficiency appeared but did not reach statistical significance.

Amblyopia is a major risk factor that should be taken into consideration during surgery of an esotropia.