Henle's Fiber Layer Thickness and Area Measurement in Type 2 Diabetes Mellitus with and without Retinopathy Using a Modified Directional Optical Coherence Tomography Strategy.

PURPOSE: To investigate Henle's fiber layer (HFL), outer nuclear layer (ONL), and outer plexiform layer (OPL) thicknesses and areas in the eyes of patients with diabetes with no diabetic retinopathy (NDR), in eyes with non-proliferative diabetic retinopathy without diabetic macular edema (NPDR), and in healthy eyes using a modified directional optical coherence tomography (OCT) strategy.

METHODS: In this prospective study, the NDR group included 79 participants, the NPDR group comprised 68, and the control group had 58 participants. HFL, ONL, and OPL thicknesses and areas were measured on a horizontal single OCT scan centered on the fovea using directional OCT.

RESULTS: The foveal, parafoveal, and total HFL were significantly thinner in the NPDR group than in the NDR group and the control group (all p<0.05). The NDR group had significantly thinner foveal HFL thickness and area compared with the control group (all p<0.05). The NPDR group had significantly thicker ONL thickness and area in all regions than the other groups (all p<0.05). The OPL measurements did not differ between the groups (all p>0.05).

CONCLUSION: Directional OCT provides isolated thickness and area measurement of HFL. In patients with diabetes, the HFL is thinner, and HFL thinning begins before the presence of DR.