Ocular Rigidity and Outflow Facility in Nonproliferative Diabetic Retinopathy

Abstract

Purpose. To compare ocular rigidity (OR) and outflow facility (C) in patients with nonproliferative diabetic retinopathy (NPDR) and control subjects. Methods. Twenty-four patients with NPDR (NPDR group) and 24 controls (control group) undergoing cataract surgery were enrolled. NPDR group was further divided into patients with mild NPDR (NPDR1-group) and patients with moderate and/or severe NPDR (NPDR2-group). After cannulation of the anterior chamber, a computer-controlled device was used to infuse saline and increase the intraocular pressure (IOP) in a stepping procedure from 15 to 40 mmHg. Ocular rigidity and outflow facility coefficients were estimated from IOP and volume recordings. Results. Ocular rigidity was 0.0205 μL−1 in NPDR group and 0.0202 μL−1 in control group (P=0.942). In NPDR1-group, OR was 0.017 μL−1 and in NPDR2-group it was 0.025 μL−1 (P=0.192). Outflow facility was 0.120 μL/min/mmHg in NPDR-group compared to 0.153 μL/min/mmHg in the control group at an IOP of 35 mmHg (P=0.151). There was no difference in C between NPDR1-group and NPDR2-group (P=0.709). Conclusions. No statistically significant differences in ocular rigidity and outflow facility could be documented between diabetic patients and controls. No difference in OR and C was detected between mild NPDR and severe NPDR.