Multifocal electroretinogram in insulin dependent diabetes mellitus type I

Background Diabetic retinopathy (DR) is one of the leading causes of new blindness. The multifocal electroretinogram (mfERG) has been demonstrated to be useful in objective assessment of various retinal disorders. Objective To evaluate the retinal function by mfERG in adolescents with insulin dependent diabetes mellitus type 1 (IDDMT-1) without clinically evident DR. Patients and methods A case/control study carried out on 30 adolescents (30 eyes) with IDDMT-1 for 5 years' duration or more in comparison with 20 healthy adolescents (40 eyes). Cases with DR were excluded based on ophthalmological examination, slit-lamp biomicroscopy and fluorescein angiography. mfERG-P1 wave-peak time and amplitude were measured and expressed in the form of four quadrants and fovea. Results In diabetic adolescents, mfERG-P1 wave had small amplitude in the four examined quadrants. The foveal response was small in amplitude and delayed in time as well. There is a significant negative linear correlation between the ages of the diabetic adolescents, the duration of illness, the glycosylated hemoglobin level and the amplitude of mfERG-P1 wave in the upper nasal quadrant only. Conclusion Homogeneous reduction of the amplitude of the mfERG test in IDDMT-1 goes with the diffuse nature of the microvascular affection of the retina even before the retinopathy becomes clinically evident.