Ocular rigidity and outflow facility in nonproliferative diabetic retinopathy

To compare ocular rigidity (OR) and outflow facility (C) in patients with nonproliferative diabetic retinopathy (NPDR) and control subjects.

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.

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).

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.