Anatomical and functional responses in eyes with diabetic macular edema treated with “1 + PRN” ranibizumab: one-year outcomes in population of mainland China

BACKGROUND: To evaluate the anatomical and functional responses in eyes with diabetic macular edema (DME) treated with ranibizumab under "1 + pro re nata (PRN)" regimen. METHODS: This prospective interventional case series included 69 eyes of 69 patients with DME treated with intravitreal injections of 0.5 mg ranibizumab followed by repeated injections as needed. Best-corrected visual acuity (BCVA), central foveal thickness (CFT), subfoveal choroidal thickness (SFCT), and predictive factors for final visual outcomes were assessed. RESULTS: Logarithm of minimal angle of resolution (logMAR) BCVA improved from 0.64 ± 0.23 at baseline to 0.56 ± 0.27, 0.53 ± 0.26, 0.47 ± 0.25, 0.44 ± 0.32, 0.47 ± 0.26 and 0.46 ± 0.26 at time-point of months 1, 2, 3, 6, 9, and 12, respectively (P < 0.05 for any follow-up time-point except month 1). CFT decreased from 478.23 ± 172.31 μm at baseline to 349.74 ± 82.21 μm, 313.52 ± 69.62 μm, 292.59 ± 61.07 μm, 284.67 ± 69.85 μm, 268.33 ± 43.03 μm, and 270.39 ± 49.27 μm at above time-points, respectively (P < 0.05). The number of injections was 6.83 times over 12 months' follow-up under "1 + PRN" regimen. Multivariate analysis showed that the factors including age, BCVA at baseline, disruption of ellipsoid zone, posterior vitreous detachment (PVD), and vitreomacular traction (VMT) were correlated with the final BCVA. CONCLUSIONS: Intravitreal injections of ranibizumab under "1 + PRN" regimen is a not only effective but also safe way to improve visual acuity of DME patients. And older age, lower baseline BCVA, VMT, and disruption of ellipsoid zone are predictors for final poor BCVA while PVD is a positive predictive factor for good final BCVA. TRIAL REGISTRATION: The trial was registered retrospectively in ClinicalTrials.gov on 2 June 2019 (NCT03973138).