Comparison of chromatic macular ERG and multifocal ERG in diabetic macular edema

Abstract

Abstract Purpose: To evaluate the degree of macular function disturbances in patients with diabetes mellitus and high glycosylated haemoglobin (HbA1c). Methods: 11 patients with type II diabetes were included in our study. In 6 patients a clinically significant macular edema was detected; other 5 patients showed slight vascular changes and absence of macular pathology. All patients had much too high (8‐10%) or extremely high (above 10%) levels of HbA1c and underwent a chromatic macular ERG test to red, green and blue stimuli (MBN, Russia). A RETIScan system for multifocal ERG was also used (Roland Consult, Germany). Results: Patients with macular edema and long duration of the disease had significant reduction of a‐ and b‐wave amplitudes of macular ERG, whereas those with short duration of diabetes showed slight decrease of macular ERG amplitude. The density of photoreceptors in multifocal ERG and amplitudes of N1 and P1 components were analyzed in area of 15° of visual angle: the mean of 3 central rings’ values was calculated. Correlation between mf‐ERG data and macular ERG amplitudes were found. In patients without macular edema and duration of the disease from 7 to 10 years who had background diabetic retinopathy no significant changes of function testing of the macula were revealed. The amplitude values were close to lower normal data. Conclusions: Macular function in diabetic patients is mainly safe in spite of high levels of glycosylated haemoglobin. The complexity of pathogenetic mechanisms of diabetic retinopathy along with functional tests is still the subject of an investigation.