Long-term follow-up of retinal blood flow in diabetes using the blue light entoptic phenomenon

The blue light entopic phenomenon was used to measure retinal blood flow in 87 diabetics and 10 normal controls in a longitudinal study. The time interval between the initial and final studies was 21-39 months (mean 31.4). The retinal blood flow velocity did not change in the 10 subjects in the control group nor in those nine patients with no retinopathy, all but one of whom remained free of retinal lesions. In the 24 with background retinopathy the flow velocity fell significantly from 0.71 (SD 0.35) mm/s to 0.48 (0.13) mm/s (p less than 0.01). The velocity also decreased in the preproliferative group of 16 patients from 0.62 (0.39) mm/s to 0.41 (0.14) mm/s (p less than 0.05). The retinopathy status changed in 11 of this group. In those with proliferative retinopathy (now treated) and those treated previously there was no change in flow velocity.