The capillary blood flow in ischaemic type central retinal vein occlusion: the effect of laser photocoagulation

Purpose: To determine the effect of photocoagulation on retinal blood flow (RBF) in eyes with ischaemic type central retinal vein occlusion (CRVO). Patients adn Methods: Retinal blood flow was measured in 12 eyes with CRVO, 12 fellow eyes and 12 eyes of 12 age-matched healthy subjects using the Heidelberg retinal flowmeter (HRF). Microvascular blood flow values (volume, flow, velocity) were recorded from the upper temporal retina and macula. Eyes were re-examined 1 month after photocoagulation. We investigated whether there was a difference in RBF measurements before and after photocoagulation treatment. Results: In eyes with CRVO, mean RBF values (volume, flow and velocity) obtained from the upper temporal retina increased significantly after treatment (paired t -test, p < 0.05). In contrast, mean RBF values from the macula were unaffected by photocoagulation (paired t -test, p > 0.05). Retinal blood flow values from the upper temporal retina obtained from control subjects were significantly higher than the values in eyes with CRVO before and after photocoagulation (unpaired t -test, p < 0.05), but there was no significant difference between control subjects and CRVO patients in RBF values from the macula (unpaired t -test, p > 0.05). Mean RBF values were significantly higher in CRVO patients' fellow-eyes before photocoagulation in the eyes with CRVO (paired t -test, p < 0.05) but were lower than in age-matched healthy control eyes (unpaired t -test, p < 0.05). Macular blood flow did not differ between the eyes with CRVO and fellow eyes (paired t-test, p > 0.05). Conclusion: Laser photocoagulation increased retinal blood flow in eyes with CRVO, but RBF did not reach normal values. Photocoagulation was found to have no effect on RBF in the macular area.