The effect of preset intraoperative intraocular pressure during phacoemulsification on the blood flow velocity in the central retinal artery

Abstract

Aim. To evaluate the effect of preset elevated intraocular pressure (IOP) level during phacoemulsifica-tion on central retina artery and central retinal vein hemodynamics and to determine possible compensator y mechanisms of the ocular blood flow autoregulation in response to intraoperational IOP jump. Methods. This prospective study included 23 cataract patients without concomitant ocular vascular conditions (15 women and 8 men) aged from 62 to 83 years. The mean age was 72.5 ± 5.7 years. In all patients, an intraopera-tional color duplex scanning in the regimens of color Doppler imaging and pulsed wave velocity imaging using ultrasound scanner Logiq S8 (GE). The blood flow was estimated in retrobulbar vessels: central retinal arter y, central retinal vein with maximal systolic velocity, end-diastolic velocity of the blood flow, and resistance index (RI). The investigation was performed under IOP control, which was measured using Icare Pro tonometer, and under blood pressure control using patient monitoring system Draeger Vista 120. In the operating room, ocular blood flow was examined three times: immediately before surger y, straight after the surgical incision sealing at preset intraoperational IOP level, and after IOP normalization and repeated sealing of the corneal tunnel. Results. Under preset intraoperational IOP maintenance on 58.01 ± 8.10 mm Hg level, there was a clinically significant (p < 0.05) decrease of blood flow velocity in the central retinal arter y. In 30.4% of cases, the blood flow velocity in the central retinal arter y during diastolic phase was not registered. The flow velocity in central retinal vein did not change significantly, and did not depend on IOP level (p < 0.05). Conclusions. At the 55–60 mm Hg IOP level, in humans, compensator y blood f low autoregulation mechanisms in response to intraoperational IOP jumps are absent, up to complete blood flow stop in the central retinal artery at the diastolic phase, and this could be a risk factor for retinal ischemia.