Characteristics of Retinal Nerve Fiber Layer Defect in Nonglaucomatous Eyes With Type II Diabetes

To investigate the characteristics of retinal nerve fiber layer (RNFL) defects associated with type II diabetes.Forty nonglaucomatous eyes with type II diabetes and 54 eyes with early open angle glaucoma that exhibited a localized RNFL defect and 42 eyes from age- and sex-matched nondiabetic, nonglaucomatous controls were imaged with red-free fundus photography and optical coherence tomography (Cirrus HD-OCT, Carl Zeiss Meditec). The area under the receiver operating characteristic curves of eyes with diabetes was compared with that of eyes with glaucoma. When an RNFL defect on fundus photographs was identified in the quadrant, clock-hour, temporal-superior-nasal-inferior-temporal (TSNIT), deviation, and thickness maps, it was considered a true detection.In eyes with diabetes, the RNFL defects were located more frequently in the superior hemisphere than they were in those with glaucoma (P < 0.001). The angular locations of RNFL defects in eyes with diabetes (56.1 ± 12.7°) were significantly farther from the fovea compared with those in glaucoma (44.3 ± 17.3°; P < 0.001); in addition, the width of RNFL defects in diabetes (5.1 ± 2.3°) was significantly narrower than those in glaucoma (20.8 ± 12.3°; P < 0.001). The best parameter discriminating RNFL defects in diabetes from those in glaucoma was width of RNFL defect (0.955), followed by rim area (0.844), and average RNFL (0.791). The thickness map showed a sensitivity (70%) and specificity (69.1%), superior to those of all other maps in eyes with diabetes.The narrow width and identification of RNFL defect in thickness map obtained with Cirrus HD-OCT seems to be an effective tool for detecting RNFL defects in diabetes.