Scleral thinning after repeated intravitreal injections of antivascular endothelial growth factor agents in the same quadrant

Abstract

Purpose: We assessed the effects of intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapy on scleral architecture using spectral domain anterior segment optical coherence tomography (OCT).

Methods: A total of 35 eyes of 35 patients treated with at least 30 intravitreal injections in one eye in the inferotemporal quadrant with ranibizumab or aflibercept and 10 or less intravitreal injections in the fellow eye attending the intravitreal injection clinic were included. Enhanced depth imaging anterior segment OCT was used to measure scleral thickness. For each eye the sclera was measured in four quadrants at 3 mm from the limbus. In addition axial eye length was measured in all subjects using partial coherence interferometry.

Results: The mean number of intravitreal injections was 42 (range, 30-73) and 1.6 (range, 0-9) in the fellow eyes. In the study eyes with more than 30 injections the average scleral thickness in the inferotemporal quadrant was 568.4 μm (SD ± 66 μm) and 590.6 μm (SD ± 75 μm) in the fellow eyes with 10 or less injections (P = 0.003). The mean average scleral thickness in the other three quadrants (inferonasal, superotemporal, and superonasal) was 536.6 μm in the study eyes (SD ± 100 μm) and 545.2 μm (SD ± 109 μm) in the fellow eyes (P = 0.22). There was a borderline association of the total number of injections with scleral thickness change in the inferotemporal quadrant (r = 0.3, P = 0.052).

Conclusions: Intravitreal injections may lead to scleral changes when applied repeatedly in the same quadrant. Thus, alternating the injection site should be considered in patients requiring multiple intravitreal injections.

Keywords: anterior segment OCT; anti-VEGF; intravitreal injections; retina; sclera.