Abstract
Objective: To evaluate the effect of diabetes mellitus (DM), diabetic retinopathy, and degree of glycemic control (glycosylated hemoglobin [HbA1c]) on peripapillary retinal nerve fiber layer thickness (RNFLT) using optical coherence tomography.
Methods: The study included 126 eyes of healthy controls (n= 32) and diabetics patients (n= 31), whose ages ranged from 40 to 70 years. The diabetic group was divided into: Subgroup 1: with HbA1c <7% and Subgroup 2: with HbA1c >= 7%. All patients underwent full ophthalmic examination. HbA1c level was obtained with the A1cNow(+) system and the peripapillary RNFLT was measured using 3D-OCT 2000 Topcon (360-degree circular scan with 3.4 mm diameter centered on optic disc).
Results: The obtained data demonstrates significant decrease in peripapillary RNFLT in superior and inferior quadrants of the right eye (p= 0.000 and p= 0.039, respectively), and in superior quadrant of the left eye (p= 0.002) with impairment of glycemic control. Pearson's correlation test showed significant negative correlation of RNFLT with HbA1c in the superior quadrant in both eyes.
Conclusion: Impairment of glycemic control affects the peripapillary RNFLT mainly in the superior quadrant. This thickness also tends to decrease with long-standing DM, use of DM medications, and development of diabetic retinopathy. The measurement of peripapillary RNFLT may become a useful method to monitor early retinal changes in diabetic patients.