Scotopic Electrophysiology of the Retina during Transient Hyperglycemia in Type 2 Diabetes

Abstract

The change in scotopic signaling amplitude in the outer and middle layers of retina in subjects with diabetes was proportional to the change in capillary glucose. Cone amplitude was not influenced by hyperglycemia in this study.

Electrophysiological studies in newly onset type 2 diabetes without visible vascular retinopathy

“…In the present study, the dark-adapted white light (0.81 cd s/m 2 ) response implicit time was delayed, which may be a postreceptoral effect, but could also indicate an early alteration in photoreceptor function in patients with type 2 diabetes. This is in accordance with a recent study, which demonstrated a rod rather than a cone photoreceptor effect in diabetes [9]. This may be due to the higher metabolic rate in rods compared to cones and to the fact that hypoxia in the retina is most pronounced in the dark-adapted state [16].…”

“…1). Recording procedures were according to the ISCEV standardised protocol [8] with slight modifications: Cone responses were obtained with 30-Hz flickering white light (0.81 cd s/m 2 ) averaged from 20 sweeps without background illumination (dark adapted) [9] and with background illumination (light adapted). The cone responses were obtained without the 10 min of light adaption.…”

Baseline haemoglobin A1c influences retinal function after long-term insulin pump therapy

“…It also supports the theory that hyperglycemia can lead to a hypermetabolic state in the retina [26].…”

Retinal function in relation to improved glycaemic control in type 1 diabetes

“…Such findings are difficult to interpret, however, because retinal performance fluctuates with glycaemia, [32][33][34], which is inherently unstable in diabetes. Specifically, an acute increase in glycaemia has been shown to accelerate light-adapted cone function, increase dark-adapted rod sensitivity and accelerate rod dark adaptation in patients with diabetes [16,35,36]. Furthermore, there is also an effect of participants' long-term glycaemia history [16,35].…”

“…We postulate the existence of a retinal mechanism that balances aerobic and anaerobic metabolism so that performance and sustainability are optimised for a given balance between oxygenaemia and glycaemia. This hypothetical mechanism would need to be reset when glycaemia is reduced relative to oxygenaemia by intensified insulin treatment [16,35,36]. In this context Müller cells, contributing to the b-wave of the ffERG responses [43], play an important role in the normal function of the retina as they are involved in the uptake and degradation of the neurotransmitters glutamate and γ-aminobutyric acid, in the formation of the blood-retinal barrier and in the provision of glucose to the photoreceptors Values are mean ± SD No significant variations in multifocal electroretinography amplitudes and implicit times were observed over time [4].…”