A Study of Retinal Nerve Fiber Layer Thickness by using Spectral Domain Optical Coherence Tomography in Older Adults with Diabetes Mellitus

Introduction: Peripapillary retinal nerve fiber layer (RNFL) thinning occurs in the diabetic patients earlier than the detectable diabetic retinopathy. We conducted this study to evaluate the RNFL thickness and macular thickness in elderly diabetic patients using optical coherence tomography in comparison to healthy controls. Material and methods: One fifty study participants were divided in 3 groups (50 each): normal subjects, patients with diabetes with no detectable diabetic retinopathy (NDR) and patients with diabetic retinopathy (DR) of differing severity. The RNFL thickness and macular thickness was measured using spectral-domain optical coherence tomography (SD OCT). Results: The RNFL thickness around the optic disc differed significantly among all the 3 groups and tended to become thinner as the patient develops DR in elderly subjects. The mean, superior-temporal and upper nasal peripapillary RNFL thickness differed among all the 3 groups. We observed that, mean superior, temporal, inferior and nasal RNFL tended to be thinner as the patient develops DR. Conclusion: The RNFL thickness, macular thickness and ganglion cell complex thinning differed significantly between the healthy group and diabetic group without clinical DR. The RNFL thinning (measured by Spectral-domain OCT) is an early neurodegenerative ocular change in diabetic patients even before onset of diabetic retinopathy.