Ocular blood flow velocities in patients with proliferative diabetic retinopathy before and after scatter photocoagulation: a prospective study.

INTRODUCTION

Color Doppler imaging allows for simultaneous two-dimensional anatomical imaging and Doppler measurement of blood flow velocity. Chemicals are released during the development of a thermal lesion caused by photocoagulation.

METHODS

A prospective study compared ocular blood flow velocities (ophthalmic artery, posterior ciliary arteries, central retinal artery, central retinal vein and vortex veins) before and 30 minutes after the first episode of scatter photocoagulation (650, 0.1 s, 500 microns argon laser) in 25 patients with proliferative diabetic retinopathy, using a color Doppler imaging unit (Toshiba Sonolayer SSA-270 A with a 5.0 MHz PLF-503 ST phased-array scanning head).

RESULTS

Systolic, diastolic and mean arterial blood flow velocities were higher after photo-coagulation than before. There was a significant difference in the ophthalmic artery; diastolic (P < 0.01), mean velocity (P < 0.05), posterior ciliary arteries; systolic (P < 0.01), diastolic (P < 0.001), mean velocity (P < 0.05), central retinal artery; mean velocity (P < 0.05), central retinal vein; systolic (P < 0.001) and vortex veins; systolic (P < 0.01), diastolic (P < 0.01). Ophthalmic artery systolic and end-diastolic velocities declined with age in diabetic patients before scatter photocoagulation; these changes were not significant (systolic: r = -0.33, diastolic: r = -0.30).

DISCUSSION

During and after thermal lesion caused by photocoagulation, there is a dynamic inflammatory and an autoregulatory response of the retinal circulation, causing changes in the ocular circulation.