Exotropia Surgery Outcomes Are Better for Patients With Hyperopia Than Emmetropia

Exotropia surgery outcomes are superior for patients with hyperopia compared with emmetropia, according to research published in BMC Ophthalmology. While the surgery’s success rate was similar for both groups at years 1 and 2 postoperatively, researchers report significant differences in successful alignment at final exam. 

The purpose of the study was to assess what effect hyperopia might have on basic-type exotropia surgery outcomes. Researchers retrospectively analyzed medical records from 75 patients (mean age, 5.1±2.6 years; 24 men, 51 women) with exotropia who underwent corrective surgery and were followed for at least 2 years. The patients were stratified by preoperative spherical equivalent (SE) into a hyperopia group (n=21) and an emmetropia group (n=54).

The success rate of exotropia surgery was higher for the patients in the hyperopia group compared with the emmetropia group at 1 and 2 years and the final examination, according to the researchers; however, this trend was only significant for the final examination (52.4% vs 27.7%; P =.040). 

At the final follow-up visit, exotropia recurred in 10 (47.6%) patients in the hyperopia group and 38 (70.4%) patients in the emmetropia group, the researchers report. Patients in the hyperopia group maintained surgical success longer compared with patients in the emmetropia group (63.5 vs 53.0 months). The difference in cumulative probability of surgical success was not statistically significant. Sensory outcomes, such as postoperative stereoacuity were comparable between the 2 groups.

In the context of other available data, the effect of refractive error on exotropia surgery outcomes remains unclear. This study aligns with some data that suggest that hyperopia may be a good prognostic factor for surgical outcomes. However, other studies report no effect. 

“Whether the refractive error is a risk factor for exotropia surgery is still debatable,” the study authors conclude. 

Limitations of this study included lack of axial length measurements, lack of analysis for postoperative follow-up refractive errors, and lack of study of the relationship between success rate and multiple studies.