Changes of Macular and Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography in Diabetic Patients with and without Diabetic Retinopathy

Introduction: Diabetes mellitus (DM) is one of the leading causes of blindness. The long-term effects of DM on vascular tissues and its consequence on the retina are well-established, and this ranges from milder grades of non-proliferative diabetic retinopathy (NPDR) to advanced grades of proliferative retinopathy with or without clinically significant macular edema. Materials and Methods: The retinal nerve fiber layer (RNFL) and macular thickness were measured in 100 patients (200 eyes) using spectral domain optical coherence tomography in the prospective observational study. The patients with DM over 40 years of age were included. Patients with a history of recent ocular surgery (1 month), pseudoexfoliation, pigment dispersion syndrome, thyroid dysfunction, long-term steroid users, high myopia, and media opacities such as cataract, other causes for secondary glaucoma, and DR with tractional retinal detachment, and post glaucoma and retinal surgery were excluded. The values of participants with DM were compared to controls. The participants were divided into 4 groups of containing 25 patients in each group: Controls (normal patients without diabetes), diabetics without retinopathy (NDR group), NPDR (NPDR group), and proliferative DR (PDR group). Results: The average temporal RNFL thickness and average macular thickness are 65.02 mu m and 278.46 mu m, respectively. It is significant (P < 0.01) across the groups. Conclusion: DR is associated with a decrease in RNFL thickness though this is not statistically significant in our study. However temporal RNFL shows a significant increase in thickness, which worsens with the stage of DR, this is due to the clinical significant macular edema which is associated with the retinopathy.