Macular ischaemia as a marker for nephropathy in diabetic retinopathy

To determine whether diabetic macular ischaemia is associated with ischaemic heart disease (IHD), hyperlipidaemia, hypertension (HTN) and nephropathy.

Prospective case-control study from January to December 2001, involving 102 type 2 diabetic patients (aged 40-80 years), 59 with unilateral / bilateral macular ischaemia and 43 concurrent controls. Diabetic retinopathy was graded and macular ischaemia assessed by fundus examination, central fundus photography and fluorescein angiography. Systemic examination and laboratory investigations were done to evaluate systemic diseases. The associations were analysed by Chi-square test and Student's t-test. The significance of the variables as independent risk factors was tested by logistic regression analysis.

Macular ischaemia was not associated with IHD (P=1.00); HTN (P=1.00) and hyperlipidaemia (P=0.30). Nephropathy was significantly associated with macular ischaemia (P=0.025; odds ratio [OR]: 2.62; 95% confidence interval [CI]: 1.16-5.9). The association remained significant after controlling for age, gender, duration of diabetes, severity of retinopathy, HTN, IHD and hyperlipidaemia. Further, the association with nephropathy was not affected by the presence of macular isachaemia in one or both the eyes (P=0.39).

Macular ischaemia may serve as a marker for nephropathy in type 2 diabetes mellitus irrespective of the severity of retinopathy.