Assessment of macular vascular density following strabismus surgery for exotropia

The aim of this study was to evaluate retinal vessel density (VD) following horizontal muscle surgery performed to treat exotropia.

This study included 23 patients who underwent unilateral strabismus surgery to treat exotropia in the Department of Ophthalmology at Dicle University. The operated eyes were compared with the contralateral, non-operated eyes. All patients underwent a comprehensive ophthalmological examination preoperatively and postoperatively. Best-corrected visual acuity was measured, and Hirschberg and prism cover tests were performed. All optical coherence tomography angiography measurements were performed by the same technician using an AngioVue OCT device (Optovue, Fremont, CA, USA). Only images with a signal strength of ≥ 70 were included. A 3 × 3 mm scan protocol was used to evaluate the macular region.

The mean patient age was 16.6 ± 5.1 years, the mean deviation angle was 25.9 ± 8.2 prism diopters, and the mean follow-up period was 3.6 ± 1.9 months. No significant differences were observed between the operated and control eyes in terms of the foveal avascular zone area and perimeter, superficial capillary plexus VD, and retinal thickness (p > .05). However, the deep capillary plexus (DCP) VD was significantly lower in the operated eyes compared with the control eyes in the parafoveal, parafoveal inferior, parafoveal nasal, and parafoveal superior hemi sectors (p = .022, p = .044, p = .019, and p = .015, respectively). Correlation and regression analyses revealed that age, follow-up duration, deviation angle, and extent of muscle surgery were not associated with these differences.

The lower VD observed in the DCP in the operated eyes may indicate that the surgery resulted in subtle alterations in retinal microvascular perfusion. Hence, future studies should investigate whether strabismus surgery has long-term effects on retinal perfusion and sensitivity and elucidate the underlying causes of any such effects.