Impact of different intraocular pressures during cataract surgery on retinal perfusion in eyes with diabetic retinopathy: randomized clinical trial

Purpose: To study the effect of varying preset intraocular pressure (IOP) levels during phacoemulsification on the retinal perfusion using optical coherence tomography angiography (OCTA) in eyes with nonproliferative diabetic retinopathy (NPDR). Setting: Iladevi Cataract & IOL Research Centre, Ahmedabad, Gujarat, India. Design: Randomized clinical trial. Methods: Patients undergoing cataract surgery with NPDR were randomized (1:1) to low (20 mm Hg) and high (55 mm Hg) intraoperative IOP. Primary outcome measure was percentage (%) change in central retinal vessel density (CRVD) on OCTA. Secondary outcome measures included impact on optic nerve perfusion (Flux Index [FI]) on OCTA and comparison of postoperative IOP. Outcome measures were evaluated within 2 hours of surgery, as well as on days 1, 7, and 30 postoperatively. Results: 40 eyes (40 patients) were recruited in each group. CRVD increased postoperatively, with a statistically significant increase at 1 week and 1 month in the low (vs high) IOP group. The reduction in perfusion density in the radial peripapillary capillary region did not differ significantly between groups. FI improved postoperatively in both groups, with significant improvement in the low (vs high) IOP group at each follow-up visit. Postoperative IOP was comparable between groups, with a trend toward higher levels in the high IOP group. Conclusions: Low IOP (20 mm Hg) during cataract surgery of eyes with preexisting vascular compromise may have a beneficial effect on macular and optic nerve head perfusion, especially in the early postoperative period.