Yoshihito Sakanishi, Ami Lee, Ayumi Usui-Ouchi, Rei Ito, Nobuyuki Ebihara

The purpose of this study was to determine the clinical efficacy of low-frequency intravitreal ranibizumab to treat macular edema due to retinal vein occlusion (RVO). This was a retrospective examination of cases that received intravitreal ranibizumab for untreated RVO over a period of 12 months. Instead of the conventional three monthly injections, injections were given once during the introductory period. If the recurrence of macular edema was diagnosed during the monthly visit, additional injections were given as needed. There were 21 eyes of 21 patients with branch RVO (BRVO) and ten eyes of ten patients with central RVO (CRVO). The parameters examined included the number of injections over the 12-month period, improvements in best-corrected visual acuity (BCVA), and the central macular thickness (CMT). For BRVO, preinjection parameters that had an effect on the prognosis of BCVA after the 12-month period were also examined. The total mean number of injections over the 12-month period was 3.4 for CRVO and 2.1 for BRVO. For CRVO, the BCVA in log minimum angular resolution changed from a preinjection value of 0.80 to 0.55 at 12 months. For BRVO, the change was from 0.51 to 0.30. For all diseases, BCVA improved after 12 months compared with the preinjection values (P<0.05). There was improvement in the CMT, and the CRVO changed from 765.0 μm at preinjection to 253.5 μm 12 months later. BRVO changed from 524.1 to 250.1 μm, and pre-injection BCVA was associated with a prognosis of visual acuity after 12 months of the initial injection (P=0.0485). Even with a low number of injections during the introductory period, there were still improvements in both visual acuity and CMT in RVO patients after 12 months, indicating that it was an effective treatment.