We investigated the effectiveness of a treat-and-extend regimen (TAE) of intravitreal ranibizumab injections for macular edema (ME) due to branch retinal vein occlusion (BRVO). We retrospectively examined 2-year results of 32 eyes of 32 patients who underwent TAE to treat ME due to BRVO. The patients whose treatment interval extended to ≥ 12 weeks were switched to a pro re nata regimen (PRN). For the patients whose treatment interval was <12 weeks, TAE was continued. At 2 years, 10 eyes had required no additional injections after the initial treatment period [recurrence(−) group], whereas the other 22 eyes required additional treatment [recurrence(+) group]. Among the recurrence(+) patients, 11 eyes (34.4% of total) were eventually switched from TAE to PRN; the other 11 eyes (34.4%) continued TAE for 2 years. Visual acuity and central retinal thickness were significantly improved in both the recurrence(+) and (−) groups, and there was no significant betweengroup difference in visual acuity at 2 years. Univariate analyses revealed significant differences in visual acuity (p=0.004), age (p=0.014), and vessel occlusion site (p=0.018) between these groups. Our results suggest that TAE may be effective for BRVO patients with lower visual acuity, older age, and occlusion of a major vein
