To evaluate the high myopia effect on the incidence and severity of diabetic retinopathy.

This study was a paired matched, case – control study in which 58 diabetic patients, with myopic anisometropia greater than -6 diopters, were selected among 1450 diabetic patients. These patients had been referred to eye clinic of Hamedan University of Medical Sciences from 2006 to 2013.Myopic eyes were selected as the case group and non-myopic eyes as the control group for controlling potential systemic confounding factors. These patients were studied from the viewpoint of type and degree of refractive errors and diabetic retinopathy, so complete ophthalmic examination was performed. Eventually all information gathered and statiscal analyses were performed using stata software.

Mean age of patients was 60 ± 12 years, ranged from 24 to 80 years. Of 58 patients, 22 patients were male and 36 were female. Sixty percent of patients had type 1 and other forty percent had type 2 diabetes mellitus. Mean refractive error was -7.5 diopter in myopic eye and +0.5 diopter in non-myopic eye (P=0.03).Mean axial length was measured 26.89±1.5 mm in the myopic eyes and 21.23±0.65 mm in the non-myopic eyes (P=0.020).Diabetic retinopathy appeared to some degrees in all non-myopic eyes whereas, it was observed only in 16 (27.59%) myopic eyes (P=0.010).

High myopia and greater axial length are associated with lower incidence and severity of retinopathy in diabetic patients