Early macular dysfunction detected by focal electroretinographic recording in non-insulin-dependent diabetics without retinopathy

Abstract

The focal electroretinogram, which measures the functional integrity of the distal retina of the macula, was recorded with a hand-held stimulator-ophthalmoscope in 26 eyes from patients with non-insulin-dependent diabetes mellitus with normal fundus photography, and in 52 control eyes of similar age range. Implicit time and amplitude of the responses were studied as a function of the age, glycemic control through glycosylated hemoglobin measurement and duration of diabetes. Implicit time and amplitude were significantly delayed (F=5.05, p=0.028) and reduced (F=11.26, p=0.013) in diabetic patients without diabetic retinopathy compared to control subjects. Moreover, there was a significant relationship between the implicit time (r=0.57, p=0.002) and amplitude (r=-0.65, p=0.0004) with the duration of diabetes but not with hemoglobin Alc. These results strongly suggest an early macular dysfunction in non-insulin-dependent diabetes mellitus before the appearance of diabetic retinopathy.