Arterial blood flow characteristics in central retinal vein occlusion and effects of panretinal photocoagulation treatment: an investigation by colour Doppler imaging

Aims-To determine whether an increase in vascular resistance in the central retinal and ophthalmic arterial circulations contributes to the developmen t of central retinal vein occlusion (CRVO), or haemodynamic alterations in central retinal and ophthalmic arteries occur secondary to the vein occlusi on as increased intravascular pressure is transferred through the capillary bed to the arterial side and the effect of panretinal photocoagulation tre atment on these circulations in ischaemic cases. Methods-The ophthalmic and central retinal arteries of the affected and non affected eyes of 20 patients with nonischaemic CRVO, 13 patients with ischa emic CRVO, and 22 control subjects were investigated by colour Doppler imag ing. Panretinal photocoagulation (PRP) treatment was applied to the eyes wi th ischaemic CRVO. Maximum and minimum blood flow velocities, and resistivi ty indexes were calculated in the affected and healthy eyes of patients and in the control eyes. Results-Average blood flow velocity in the central retinal and ophthalmic a rteries of patients with non-ischaemic CRVO did not differ from their fello w eyes, but a significantly lower average blood flow velocity was found in the ophthalmic and central retinal arteries of the patients with ischaemic CRVO compared with their fellow eyes. Patients with ischaemic CRVO had sign ificantly lower blood flow velocities in their ophthalmic and central retin al arteries than non-ischaemic cases that were further reduced following PR P treatment. Conclusion-This study suggests that impaired arterial blood flow observed i n patients with CRVO may be partly related to secondary changes in the retr obulbar arterial circulation as a result of enhanced arterial resistance fo llowing CRVO. These data also demonstrate that PRP treatment decreases reti nal and ophthalmic blood flow velocities in patients with ischaemic CRVO.