Study of retinal nerve fiber layer in patients with type 2 diabetes mellitus

Abstract

Purpose: (1) To assess the Retinal nerve fiber layer (RNFL) thickness in patients with type 2 diabetes mellitus (DM). (2) To assess the correlation of RNFL thickness with duration of DM and HbA1c levels. Methods: The study included 200 patients divided into three groups. Group A included 50 patients with type 2 DM without diabetic retinopathy (DR), group B included 50 patients with type 2 DM with mild to moderate NPDR, and group C included 100 age- and gender-matched controls. The duration of DM and HbA1c values were recorded. Optical coherence tomography scanning was performed, and the RNFL thickness was obtained. Results: The thickness of RNFL was less among diabetics than non-diabetics for the whole of the optic disc as well as for every quadrant except nasal quadrant. This difference was statistically significant only in the inferior quadrant (p = 0.035). The correlation coefficient between RNFL thickness of the whole of the optic disc and duration of DM and HbA1c level was -0.139 and 0.114, respectively. Conclusion: We conclude that the RNFL thickness is reduced in diabetic patients as compared to non-diabetic subjects. This may be beneficial for diabetic patients for early diagnosis of diabetic retinopathy irrespective of duration of DM or HbA1c levels.