title: Effect of panretinal photocoagulation on retinal blood flow in proliferative diabetic retinopathy.
abstract: The effect of panretinal photocoagulation (PRP) on retinal volumetric blood flow rate and its regulatory response to hyperoxia was investigated in a main temporal vein of 15 eyes with proliferative diabetic retinopathy, using bi-directional laser Doppler velocimetry and monochromatic fundus photography. At an average of 4 +/- 2 months after the beginning of PRP, retinal venous diameter decreased from an average of 174 +/- 20 micron to 162 +/- 19 micron (P less than 0.01), red blood cell velocity decreased from 1.3 +/- 0.4 cm/sec to 1.1 +/- 0.4 cm/sec (P less than 0.01), and blood flow decreased from 11.5 +/- 3.8 microliter/min to 8.4 +/- 3.3 microliter/min (P less than 0.001). The regulatory response to hyperoxia, characterized by the percentage decrease in retinal blood flow during 100% oxygen breathing, improved from 20 +/- 15% prior to treatment to 45 +/- 12% following treatment (P less than 0.001). The decrease in retinal blood flow is most likely due to a decrease in viable retinal tissue and an improvement in retinal oxygenation following PRP. The increase in the regulatory response to 100% O2 breathing following PRP may also result from such an improved retinal oxygenation.
mesh_terms: D000328:Adult; D000367:Age Factors; D001783:Blood Flow Velocity; D001786:Blood Glucose / Q000032:analysis; D003930:Diabetic Retinopathy / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008028:Light Coagulation; D008875:Middle Aged; D012039:Regional Blood Flow; D012044:Regression Analysis; D012160:Retina / Q000098:blood supply*
chemical_list: D001786:Blood Glucose