Steady-state pattern electroretinogram in insulin-dependent diabetics with no or minimal retinopathy

Steady-state pattern electroretinogram (PERG) in response to sinusoidal gratings (1.7 c/deg spatial frequency; 9 × 9 deg field size) temporally modulated (sinusoidally) at 8 Hz were recorded in 40 insulin-dependent diabetics and 28 age-matched normal subjects. Visual acuity was 20/20 in all 40 patients; 31 (62 eyes) showed no sign of retinopathy and nine (18 eyes) showed a few microaneurysms on fluorescein angiography. Insulin-dependent diabetics showed a significant reduction in the PERG mean amplitude as compared with age-matched control subjects (one-way analysis of variance: p < 0.0001). Significant differences were observed between normals and diabetics without retinopathy (Scheffé test: p < 0.0001), normals and diabetics with early retinopathy (Scheffé test: p < 0.0001), no retinopathy and early retinopathy patients (Scheffé test: p < 0.05). In diabetics without retinopathy multi-factorial analysis of variance revealed a significant effect of age of onset of the disease (p < 0.01) and an interaction effect between age of onset and duration (p < 0.001) on PERG amplitude. These results suggest a possible use of the steady-state PERG to detect early macular dysfunction in insulin-dependent diabetics.