Multifocal electroretinography (mfERG) may be a valuable tool for evaluating neuroretinal dysfunction before the clinical development of diabetic retinopathy, new research suggests. The early detection of functional abnormalities may prompt clinicians with access to this technology to keep a closer eye on their diabetes patients, the researchers add.

The investigation, published in BMC Ophthalmology, found patients with diabetes without retinopathy had reduced mfERG N1–P1 amplitude and delayed P1-implicit time compared with normal controls. The research team also found implicit time and amplitude were significantly affected by diabetes duration. 

Although previous studies showed implicit time is affected more than amplitude in diabetes patients and is a better indicator of developing clinical diabetic retinopathy, the current investigation reported both may be affected in Type II diabetes. 

The study enrolled 20 eyes of 20 Type II diabetes patients without retinopathy and 20 eyes of 20 age- and gender-matched healthy controls. All study participants underwent mfERG, and the N1–P1 amplitude and P1-implicit time of each subject’s five retinal rings were measured and analyzed. Additionally, fasting blood sugar was measured within a few days of performing mfERG.

The researchers found the reduction in N1–P1 amplitude and the delay in P1-implicit time in the patients with diabetes was statistically significant in most of the assessed rings compared with the controls. Additionally, N1–P1 amplitude was negatively correlated with diabetes duration, although there was a positive correlation between P1-implicit time and diabetes duration in those with diabetes in four out of five rings.

The researchers note that more well-designed studies are needed to address some of their study’s limitations, including measuring fasting blood sugar instead of HbA1c. Additionally, some diabetes data was obtained from patient medical records, they said in their report.

Mohammed MA, Lolah MM, Doheim MF, et al. Functional assessment of early retinal changes in diabetic patients without clinical retinopathy using multifocal electroretinogram. BMC Ophthalmology. October 14, 2020. [Epub ahead of print].