Influence of panretinal photocoagulation on the ocular pulse curve

To study the ocular pulsation amplitude (an indicator of choroidal circulation) and systolic ophthalmic artery pressure after panretinal photocoagulation.

Prospectively, in 10 patients with diabetes mellitus (eight with type II and two with type I; mean age, 64 years) and severe, hitherto untreated, bilateral proliferative diabetic retinopathy, we performed intensive, unilateral panretinal photocoagulation with 1,500 argon laser burns (spot size, 500 microm) in two sessions (interval, 3 weeks). Before and (in 3-week intervals) up to 9 weeks after treatment, we recorded ocular pulse curves using oculo-oscillodynamography and determined each patient's ocular pulsation amplitude and systolic ophthalmic artery pressure.

Compared with the untreated contra-lateral eyes, panretinal photocoagulation led to a reduction of ocular pulsation amplitude. Three weeks after the first coagulation, the reduction averaged 20%. Maximum reduction was found 9 weeks after onset of treatment (6 weeks after the second coagulation) and amounted to 29.9%. The differences between photocoagulated and untreated eyes were highly significant on average (P < .01; analysis of variance) as well as for time course (P < .001). Systolic ophthalmic artery pressure was not changed significantly during panretinal photocoagulation follow-up.

Ocular pulsation amplitude is determined by the cardiac cycle-related intraocular volume changes that depend predominantly on choroidal blood flow. The morphologic substrate is probably choriocapillary closure after photocoagulation.