Anatomical effects of intravitreal anti-vascular endothelial growth factor injections on inner layers of the lesion-free retina

Abstract

Purpose The primary aim of the study was to investigate the effects of anti-vascular endothelial growth factor (VEGF) injections on the inner retinal layer anatomy of the lesion-free retina in eyes treated for neovascular age-related macular degeneration (nAMD). The secondary aim was to compare the changes of inner retinal layers in the lesion-free region of treated eyes with the same region of the untreated, fellow eyes and, thus, to elucidate any adverse effect of anti-VEGF treatments independently of 1-year aging changes. Methods This was a retrospective, longitudinal, case–control study of 50 eyes of 25 patients. Twenty-five eyes with nAMD comprised the study group (16 eyes treated with aflibercept and 9 eyes treated with ranibizumab) and 25 fellow eyes with dry AMD (16 eyes in AREDS 2 and 9 eyes in AREDS 3) comprised the fellow eye group. Spectral-domain optical coherence tomography (SD-OCT) measurements were done at pre-treatment, 1 month after three loading anti-VEGF injections and at the end of 1 year. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL) thicknesses and total retinal thickness in the macula were measured. Thicknesses of inner retinal layers which were lesion-free in the outer nasal subfield of ETDRS grid were analysed and the changes in thicknesses during the follow-up period were compared between study and fellow eye groups. Paired t-test for normally distributed variables was applied for analyses of differences for the comparison of the results across the pre-and the post-. A p value of less than 0.05 was considered statistically significant. Results The mean number of injections was 5.76 ± 1.26 in the study group in 1 year. The mean decrease in total retinal thickness was significant with 6.08 ± 9.05 µm (p= 0.003) in nAMD group and was insignificant with 0.32 ± 1.03 µm (p> 0.05) in fellow eye group with dry AMD. Most of the retinal thickness decrease was during first three injections in nAMD group. Total retinal thickness and GCL thickness were thinner in the study group at every follow-up examination, but the difference between groups was not statistically significant (p> 0.05). RNFL, GCL, IPL, and INL thicknesses did not demonstrate a statistically significant change in both study and fellow eye groups during 1 year follow-up period (p> 0.05). Conclusions Repeated anti-VEGF injections in nAMD appear to have no significant effect on the RNFL, GCL, IPL, and INL thicknesses of the lesion-free retina. Additionally, there was no significant difference in inner retinal layer changes between in eyes treated with anti-VEGF injections for nAMD and fellow eye group during 1-year follow-up.