To evaluate prognostic factors for improvement of visual acuity after intravitreal triamcinolone acetonide injection (IVTA) for treatment of macular edema (ME) secondary to branch retinal vein occlusion (BRVO).

Sixty-eight eyes of 68 consecutive patients treated with IVTA for ME due to BRVO were retrospectively reviewed. Patients were categorized into 2 groups according to the final visual acuity. The 'gainer group' consisted of eyes with a gain of 2 or more Snellen chart lines and the 'non-gainer group' consisted of eyes with less than 2 lines improvement or which had worsened at the last follow-up visit. Comparative clinical characteristics and ophthalmoscopic examinations were analyzed between the 2 groups.

Out of the 68 eyes, 38 (56%) showed improved vision and were categorized as the gainer group; 30 eyes (44%) were categorized as the non-gainer group. The duration of symptoms in the non-gainer group was longer than the gainer group. Additionally, patients with a better baseline vision were expected to show greater improvement. The number of early visual acuity gainers who showed visual improvement at 1 month after IVTA was significantly higher in the gainer group. The number of eyes with angiographically documented macular ischemia was significantly higher in the non-gainer group. Existence of subretinal fluid has been identified as a positive factor for visual improvement.

The cases with early treatment, good baseline visual acuity, case of favorable response to the initial IVTA, absence of macular ischemia, and baseline subretinal fluid are favorable prognostic factors for the outcome of visual acuity after IVTA for ME due to BRVO.