Poster Presentation Australian Diabetes Society and the Australian Diabetes Educators Association Annual Scientific Meeting 2017

POSTER DISCUSSION: Electroretinographic findings of patients with long duration diabetes but no retinopathy:  A study using a handheld RETeval-DRTM Device (#291)

Belinda Brooks 1 2 , Yi Shi 1 3 , Ellen Landy 1 , Dennis Yue 1 3
  1. Diabetes Centre, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
  2. Sydney Nursing School, University of Sydney, Sydney, NSW, Australia
  3. Discipline of Medicine, University of Sydney, Sydney, NSW, Australia

Diabetic retinopathy increases with duration of hyperglycaemia but the presence of retinopathy in individual patients remains unpredictable.  Even in the DCCT, HbA1c only accounted for ~15% of the variation in retinopathy development.  The basis of different individual susceptibility is not clear.  In the current study we performed electroretinography on patients with a long duration of diabetes (>15 years)but no, or very minimal retinopathy.  The aim is to determine whether this setting of “normal retinal morphology” is also characterised by normal electrophysiology of the eyes.  Full-field electroretinography was performed with a handheld RETeval-DRTM device which also simultaneously measured pupillary response.  Flickering lights at 30Hz was used to stimulate retinal electrical activity which was recorded by skin electrodes placed below the lower eye lids.  Results are expressed as implicit time(speed of electrical response in msec), amplitude (uV)and real time pupil diameter(mm).  A composite score of the three parameters is also calculated and a score <20 indicates that the risk of vision threatening retinopathy is <1%.  Altogether 26 Type 2 and 9 Type 1 patients with diabetes of duration >15 years (22.5±4.5 and 32.8±9.4 years respectively)and no retinopathy were studied.  Non-diabetic controls (fasting BGL<6.0mmol/L or HbA1c<6.0 %, n=25)were similarly studied. Results in Table 1 showed that the implicit time of the individuals with diabetes was only minimally longer than normal controls, but the amplitude was significantly reduced by ~30% (p<0.01).   We conclude that eyes without diabetic retinopathy nevertheless showed abnormal retinal neural function. The EUROCONDOR Study reported that neural protection by somatostatin eye drops can retard deterioration of retinal neurophysiological parameters and microaneurysm development over a period of 2 years. Thus retinal neural changes may play a primary role in the pathogenesis of diabetic retinopathy and the individual variations of retinopathy development could be due to differing downstream response of the microvasculature.

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