Summary of select, peer reviewed published research on diabetic retinopathy:
Within the first two decades following the diagnosis of diabetes, nearly all patients with type 1 diabetes and 60% of patients with type 2 diabetes will develop retinopathy (DR). Despite better diabetes management and glycemic control, DR remains a major health concern due to an increasing number of people with diabetes. Recently, researchers have shown that diabetic retinal neural degeneration can accompany or even precede the vascular abnormalities that appear in later stages of the disease. Therefore, tracking neural dysfunction can assist in diagnosing early stages of DR and thereby possibly increase the opportunity to minimize vision loss.
The early stages of DR are usually asymptomatic. Some people may notice changes in their vision, like trouble reading or not seeing faraway objects but these changes may come and go. In the later stages, new blood vessels can begin to grow in the retina and can start to bleed. When this happens, a person may see dark, floating spots or streaks that look like cobwebs. Without treatment, the bleeding can worsen and potentially cause retinal scarring, detachment of the retina, and vision loss.
In order to track neural dysfunction, both standard multifocal (mfERG) and full-field ERG (ffERG) studies have been used. Loss of oscillatory potential (OPs) amplitude and delays in these responses are the most commonly observed ERG abnormalities in diabetes. The full-field flicker ERG amplitude can also be reduced in amplitude and delayed in diabetes. Recent work in early-stage DR suggests that the flicker ERG abnormality is most apparent at high flicker rates. Recent work has also shown a reduction in the photopic negative response (PhNR), a response that is thought to arise from retinal ganglion cells (RGC). Additionally, in patients with early stage DR, mfERG abnormalities may predict locations of new lesions based on localized changes in implicit times.
Resources:
Chen H, Zhang M, Huang S, Wu D. The photopic negative response of flash ERG in nonproliferative diabetic retinopathy. Doc Ophthalmol 2008; 117(2): 129-135.
Fong DS, Aiello L. Gardner TW, et al. Retinopathy in diabetes. Diabetes Care. 2004: 27 Suppl 1:S84-S87.
Han Y, Bearse Jr MA, Schneck ME, et al. Multifocal Electroretinogram Delays Predict Sites of Subsequent Diabetic Retinopathy. Invest Ophthalmol Vis Sci. 2004;45(3):948–954.
Harrison WM, Bearse, Jr MA, Ng JS, et al. Multifocal Electroretinograms Predict Onset of Diabetic Retinopathy in Adult Patients with Diabetes. Invest Ophthalmol Vis Sci, 2011;52 (2): 772-777.
Lakhani E, Wright T, Abdolell M, Westall C. Multifocal ERG Defects Associated with Insufficient Long-Term Glycemic Control in Adolescents with Type 1 Diabetes. Invest Ophthalmol Vis Sci. 2010;51(10):5297–5303.
Laron M, Bearse, Jr MA, Bronson-Castain K, et al. Interocular Symmetry of Abnormal Multifocal Electroretinograms in Adolescents with Diabetes and No Retinopathy. Invest Ophthalmol Vis Sci, 2012;53(1): 316-321.
Lee R, Wong TY, Sabanayagam C. Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss. Eye Vis 2015; 2:17.
McAnany JJ, Park JC. Cone Photoreceptor Dysfunction in Early-Stage Diabetic Retinopathy: Association Between the Activation Phase of Cone Phototransduction and the Flicker Electroretinogram. Invest Ophthalmol Vis Sci. 2019;60(1):64–72.
McAnany JJ, Park JC, Chau FY, et al. Amplitude Loss of the High- Frequency Flicker Electroretinogram in Early Diabetic Retinopathy. RETINA 2018, 0:1–8.
McAnany JJ, Park JC. Temporal Frequency Abnormalities in Early-Stage Diabetic Retinopathy Assessed by Electroretinography. Invest Ophthalmol Vis Sci. 2018;59(12):4872-4879.
Ng JS, Bearse MA Jr, Schneck ME, et al. Local diabetic retinopathy prediction by multifocal ERG delays over 3 years. Invest Ophthalmol Vis Sci 2008;49:1622–1628.
Park JC, Chau FY, Lim JI, McAnany JJ. Electrophysiological and pupillometric measures of inner retina function in nonproliferative diabetic retinopathy. Doc Ophthalmol 2019; 139(2):99-111.
Robson AG, Nilsson J, Li S, et al. ISCEV Guide to Visual Electrodiagnostic Procedures. Springer 2018;136:1-26.
Tzekov R, Arden GB. The electroretinogram in diabetic retinopathy. Surv Ophthalmol 1999; 44(1):53-60.
