Retinal function in normal and diabetic eyes mapped with the slow flash multifocal electroretinogram

Area of Science:

• Ophthalmology
• Diabetology
• Neuroscience

Background:

• Diabetes mellitus is a systemic disease affecting various organs, including the retina.
• Diabetic retinopathy (DR) is a leading cause of vision loss in diabetic patients.
• The standard multifocal electroretinogram (mfERG) is used to assess retinal function, but late components may be affected by diabetes.

Purpose of the Study:

• To investigate retinal function using the slow-flash multifocal electroretinogram (sf-mfERG) in diabetic subjects.
• To determine if late first-order response components are preferentially affected by diabetes mellitus and diabetic retinopathy.
• To compare the diagnostic utility of sf-mfERG components in differentiating diabetic patient groups.

Main Methods:

• sf-mfERG was performed monocularly on 18 control subjects, 12 diabetic patients without retinopathy, and 17 with nonproliferative diabetic retinopathy (NPDR).
• 103 central retinal areas were stimulated with flashes, and N1, P1, and N2 implicit times (ITs) and scalar product amplitudes (SPs) were measured.
• Abnormalities were defined as z-scores > 2.33, and group differences were analyzed based on these measures.

Main Results:

• Local functional retinal abnormalities were detected in diabetic patients with and without NPDR, predominantly in the inferior retina.
• Late components (P1 and N2) of the sf-mfERG were not preferentially affected by diabetes.
• Scalar product amplitude and P1 implicit time measures showed better group discrimination than N1 IT and N2 IT.

Conclusions:

• The sf-mfERG is a valuable tool for detecting and mapping local retinal functional abnormalities in diabetic individuals.
• Diabetes and NPDR do not selectively impair the late P1 and N2 response components of the sf-mfERG.
• sf-mfERG analysis, particularly SP and P1 IT, can help distinguish between diabetic patient groups.