Objective: To investigate the OCT macular changes in type 1 ROP one month following Ranibizumab injections.

Methods: Preterm infants with type 1 ROP indicated for Ranibizumab injections were included in this study. Handheld OCT imaging was performed at baseline, 1 week, and 1 month post injection. Central full thickness (CFT), inner retinal layer (IRL), and outer retinal layer (ORL) thickness measurements were taken from foveal center and parafoveal region.

Results: 24 eyes of 12 infants were included in this study. There were no significant changes in the mean CFT and IRL thickness at 1 month (p = 0.5 and 0.1 respectively). However, there was significant increase in the mean ORL thickness at 1 month (69.9 ± 16, 96.1 ± 25 at baseline and one month respectively, p < 0.001), with differentiation (appearance of IS/OS junction ± ELM) in 55.6% of eyes. Macular edema (ME) was observed in 12 eyes (50%) and was associated with smaller birth weight (p = 0.0290). There was no significant decrease in mean CFT in eyes with ME at 1 month (p = 0.13), with complete resolution in only 6 eyes (50%) during the study period. Regression of plus was associated with lower CFT (1 week and 1 month; p = 0.02 and 0.03, respectively).

Conclusions: Ranibizumab treated eyes in type 1 show ORL thickening and differentiation but with inadequate resolution of ME.