Macular Thickness Measured by Optical Coherence Tomography (OCT) in Diabetic Patients

Purpose 1) To compare macular thickness (MT) by optical coherence tomography (OCT) in diabetics and controls; 2) to assess the relationship between MT and stage of diabetic retinopathy (DR) and macular edema (ME); 3) to quantify MT changes after laser treatment for ME. Methods One-hundred and thirty-seven patients with diabetes mellitus (216 eyes) were admitted to the study and examined by stereo-color fundus photos, retinal fluorangiography and OCT. DR was classified as: 1) no DR (46 eyes: 21.3%); 2) background DR (66 eyes: 30.6%); 3) pre-proliferative DR (50 eyes: 23.1%); 4) proliferative DR (54 eyes: 25%). The study group was then divided into three ME groups: 1) no edema (65 eyes: 30.1%); 2) not clinically significant ME (no CSME) (45 eyes: 20.8%); 3) clinically significant macular edema (CSME) (106 eyes: 49.1%). Three-month follow-up tomograms were taken to evaluate eyes laser-treated only for ME. The control group consisted of 50 eyes of 50 non-diabetic, age- and sex-matched subjects. Results MT was 369.3±163.2 μm in diabetics and 161.9±12.9 μm in controls (p<0.001). In the four DR groups it was: 1) 211.0±37.6 μm; 2) 370.8±159.6 μm; 3) 419.1±138.2 μm; 4) 456.1±162.0 μm (p<0.001). In the three ME groups, MT was: 1) 227.8±53.4 μm; 2) 321.8±124.2 μm; 3) 476.2±146.6 μm (p<0.001). In the 52 eyes treated with laser photocoagulation of the posterior pole only and with a follow-up > 3 months, MT before and after treatment was 468.2±83. 17 μm and 372.1±120.63 μm. Conclusions MT was greater in diabetics than controls and tended to increase with DR and ME severity. OCT is a sensitive technique for detecting early diabetic macular abnormalities and quantifying their reduction after laser treatment.