The mean improvement at Day 7 was 5.3 letters ( branch retinal vein occlusion , 5.1 ; and central retinal vein occlusion , 5.8 ) with DEX implant and 1.6 letters ( branch retinal vein occlusion , 2.3 ; and central retinal vein occlusion , 0.1 ) with sham ( P < 0.001 ) .