Abstract
Purpose :
The increasing prevalence of diabetes in Africa highlights the importance of early detection of diabetic eye changes. Recent work has identified thinner (RGC) layer on Spectral Domain Optical Coherence Tomography (SD-OCT) in patients with diabetes as compared to normal controls. The purpose of this pilot work is to determine if glucose tolerance test values in an African cohort correspond with RGC thickness, potentially identifying early evidence of early diabetic changes in the eye that could precede retinopathy.
Methods :
First and second generation African volunteers above the age of 18 who self-identified as healthy were recruited through newspaper advertisements, flyers and the NIH website and seen jointly at the NIDDK and the NEI. Patients with SD-OCT or exam evidence of comorbid retinal or optic nerve pathology, previous a diagnosis of diabetes, women who are breastfeeding or have an infant less than four months of age, or women with irregular menses in the year prior to enrollment were excluded. All participants had OGTT to identify who had normal glucose tolerance, prediabetes and diabetes. Then, minimum value RGC layer thickness was calculated using the Zeiss Cirrus SD-OCT segmentation algorithm and values for both eyes were averaged for each participant.
Results :
Of 93 eligible self-identified healthy African immigrants [(61.2% male, age 41.53 ± 8.95 (mean ± SD)], 11 patients were classified as diabetic, 23 patients were classified as having impaired glucose tolerance, and 59 were classified as having normal glucose tolerance. Patients with diabetic (>200 mg/dL) glucose tolerance tests were older than those who had normal (<140 mg/dL) or impaired (140-200 mg/dL) glucose tolerance tests (p=.008). Average minimum RGC layer thickness was greatest in the normal group (84.86 µM), less in the impaired glucose tolerance group (81.15 µM) and least in the diabetic group (78.50µM), and this difference was significant (p=0.001).
Conclusions :
This pilot study suggests that average minimum RGC layer thickness corresponds with glucose tolerance in African immigrants. However, age may be a confounding factor. The next step is a longer study with longitudinal follow up.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.