Ocular and cardiovascular autonomic function in diabetic patients with varying severity of retinopathy.

The study was conducted to assess the ocular and cardiovascular autonomic function in diabetic patients with varying severity of diabetic retinopathy. Ocular and cardiovascular autonomic function tests were performed in 30 patients with type 2 Diabetes Mellitus (10 in each group of proliferative retinopathy, non-proliferative retinopathy and no retinopathy) of more than 5 years duration and 10 normal controls. Ocular autonomic function tests were done by measuring pupil cycle time and denervation hypersensitivity with 0.125% pilocarpine and 0.5% phenylephrine. Cardiovascular autonomic function was measured by a battery of standard tests. Denervation hypersensitivity to 0.125% pilocarpine and to 0.5% phenylephrine and pupil cycle time showed statistically significant differences (P value < 0.001) between controls and patients with proliferative retinopathy (PDR) and also between no retinopathy and PDR (P < 0.001). Systemic autonomic function tests namely expiration--inspiration ratio, difference in heart rate, 30th beat and 15th beat ratio in head up tilt and difference in diastolic blood pressure in head up tilt test also showed significant difference (P < 0.01) between controls and all 3 groups of diabetics. There was statistically significant difference found in para-sympathetic ocular autonomic dysfunction between NPDR and controls. Ocular and systemic autonomic dysfunctions are related to the severity of diabetic retinopathy.