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 diabetic 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.

 

References

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