Early diabetic changes in the nerve fibre layer at the macula detected by spectral domain optical coherence tomography

Aim To detect early nerve fibre layer (NFL) changes around the optic disc and macula in diabetic patients using Cirrus HD-optical coherence tomography (OCT).

Methods Forty normal patients without any optic nerve or retinal disease, 37 patients with diabetes with no diabetic retinopathy (NDR) and 89 patients with diabetic retinopathy (DR) of differing severity were enrolled. The NFL thickness around the optic disc was measured using Cirrus HD-OCT. The NFL thickness at the macula was also determined by scanning the macula with the optic disc scanning technique.

Results The NFL thickness around the optic disc differed statistically among all groups and tended to become thinner as the degree of DR progressed. The mean, superior and inferior peripapillary NFL thickness differed among groups. As the severity of DR progressed, the mean, superior, temporal, inferior and nasal macular NFL thickness tended to become thinner. However, only the macular NFL thickness of the superior sector differed significantly among the groups and especially between the control and NDR groups.

Conclusion The difference in NFL was first detected in the superior macular region, which differed significantly between the control group and diabetic group without clinical DR. This could be detected simply by modifying the Cirrus HD-OCT scan technique to detect the NFL thickness in the macular area.