Retinal thickness in healthy and diabetic subjects measured using optical coherence tomography mapping software

To define the normal retinal thickness in healthy subjects using optical coherence tomography (OCT) mapping software and to assess the ability of OCT to detect early macular thickening in diabetic patients.

Six radial scans centered on the fixation point were done on 60 healthy eyes and 70 eyes of 35 diabetic patients without macular edema on biomicroscopy. Retinal thickness was measured automatically with OCT mapping software. Mean retinal thickness was compared in subgroups of healthy patients based on age, sex, and eye, and in the eyes of diabetic patients and healthy subjects. Thickening was diagnosed if mean retinal thickness of an area was greater than the mean thickness + 2SD in the corresponding area in healthy subjects; or if the difference between right and left eye exceeded the mean difference + 2 SD in a given area in healthy subjects.

In healthy subjects, mean retinal thickness in the central macular area 1000 microm in diameter was 170+/-18 microm. There was no significant difference according to age, or left or right eye, but central macular thickness was significantly greater in men than women (p=0.0139). No difference was observed between the eyes of healthy subjects and diabetic patients without macular edema on biomicroscopy, but OCT detected early macular thickening in 12 diabetic eyes.

In this study average retinal thickness and mean local variations in a normal population were defined using a commercially available mapping software. OCT seems a sensitive tool for detecting early retinal thickening.