ObjectiveTo observe the contrast sensitivity (CS) of patients with branch retinal vein occlusion (BRVO) without involving the macular region. Methods92 BRVO patients (93 eyes) and 56 cases (112 eyes) without eye diseases (control group) were included in the study. According to different region, BRVO patients were divided into the nasal BRVO group (31 eyes) and temporal BRVO (62 eyes) group, and the average corrected visual acuity was 1.02±0.13 and 0.98±0.12 respectively. According to the type of ischemia, BRVO patients were divided into the nonischemic BRVO group (58 eyes) and ischemic BRVO group (35 eyes), the average corrected visual acuity was 1.01±0.14 and 0.99±0.12 respectively. The average corrected visual acuity of the control group was 1.03±0.11. There was no statistically significant difference of the average corrected visual acuity between nasal BRVO group, temporal BRVO group and control group (F=3.03, P=0.06), and between nonischemic BRVO group, ischemic BRVO group and control group (F=1.60,P=0.20). Contrast sensitivity (CS) was measured by OPTEC 6500 vision tester (Stereo Company, USA) under the standard lighting conditions and different spatial frequencies including low (1.5 and 3.0 c/d), medium (6.0 c/d) and high frequencies (12.0 and 18.0 c/d). ResultsThe CS under each spatial frequency of the nasal BRVO group was the same as the control group (t=4.25, 9.48, 3.08, 5.86, 0.94; P>0.05), but the CS under each spatial frequency of the temporal BRVO group was different from the control group (t=8.59, 19.11, 10.38, 17.28, 6.01; P<0.05). The CS under high spatial frequency of the temporal and nasal BRVO group was statistically different (t=11.42, 6.95; P<0.05). The CS under each spatial frequency of the ischemic BRVO group was different from the control group (t=8.88, 10.56, 11.64, 19.06, 6.67; P<0.05).The CS under 6, 12 and 18 c/d spatial frequency of the nonischemic BRVO group was statistically different with the control group (t=10.14, 11.54, 2.82; P<0.05). The CS under 12 and 18 c/d spatial frequency of the nonischemic BRVO group was statistically different with the ischemic BRVO (t=7.52, 3.84; P<0.05). ConclusionsThe CS of the temporal BRVO and ischemic BRVO decreased more significantly under each spatial frequency. CS is a better indicator to evaluate the visual function than the visual acuity in BRVO without involving the macular region.