First Author: B.Sekeryapan Gediz TURKEY
Co Author(s): M. Kaim P. Yilmazbaş
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In this study, we aimed to evaluate the outer retinal layer (ORL) thickness in patients treated with intravitreal ranibizumab due to neovascular age related macular degeneration (AMD).
This retrospective study included 84 eyes of 42 patients who underwent intravitreal ranibizumab injection for neovascular AMD in one eye (injection group) and who had dry AMD findings (dry AMD group) in the other eye
Two groups were evaluated in terms of visual acuity and ORL thickness. Number of injections in injection group was noted. ORL thickness was defined as the distance between the outer border of external limiting membrane (ELM) and the inner border of retinal pigment epithelium (RPE) at 0.5 mm from the foveal centre and measured on spectral domain optical coherence tomography (SD-OCT) scans manually. “t test” was used to compare the values. Pearson correlation coefficients were calculated to evaluate relations between ORL thickness and number of injections. Statistical significance was set at p<0.05.
Mean number of injections was 5.0 ± 2.5 (3-12) during a mean follow-up period of 22.2 ± 14.3 months. In the injection group, mean ORL thickness was measured as 94.9 ± 6.8 µm (84-111) before treatment and 88.0 ± 9.2 µm (71-110) at the end (p=0.000). In dry AMD group, the same parameters were 94.8 ± 9.4 µm (71-111) and 92.2 ± 9.4 µm (68-106), respectively (p=0.004). The difference between groups was not significant in terms of ORL thickness before treatment, but it was significant at the end (p=0.003). In the injection group, mean VA value was 0. 71 ± 0.38 logMAR (0.10-1.30) before treatment and 0.73 ± 0.73 logMAR (0.00-1.10) at the end (p=0.935). In dry AMD group, the same parameters were 0.48 ± 0.39 logMAR (0.10-1.10) and 0.46 ± 0.32 logMAR (0.10-1.00), respectively (p=0.577). The correlation coefficient between ORL thickness and number of injections were 0.505 (p=0.06).
ORL thickness has been described as the sum of length of inner and outer segments of photoreceptors and it has been suggested as a novel parameter which was better associated with visual acuity than the total foveal thickness. In our study, ORL thickness was found to be decreased significantly in two groups, however the decrease was more in injection group. Although we could not find a correlation between number of injections and ORL thickness, intravitreal anti-VEGF injections may contribute to the ORL thickness decrease caused by the natural course of the AMD.