Detection of diabetic macular edema: Nidek 3Dx stereophotography compared with fundus biomicroscopy

PURPOSE: To assess the use of the Nidek 3Dx simultaneous stereophotography camera in diabetic patients, comparing the detection of clinically significant macular edema by fundus biomicroscopy to detection by the Nidek 3Dx simultaneous fundus stereophotograph. METHODS: Two hundred eight eyes of 123 diabetic patients at the Wilmer Retinal Vascular Center were examined for this prospective study between August 1993 and October 1993. Each patient was examined by one of three retina specialists by contact lens biomicroscopy for clinically significant macular edema and foveal center thickening. Nidek 3Dx fundus stereophotographs were obtained and graded independently for clinically significant macular edema and foveal center thickening by a fourth ophthalmologist masked from the clinical examination findings. Percent agreement, kappa statistic, and weighted kappa statistic were determined for the two diagnostic methods. RESULTS: One hundred eighty- four (88%) of the 208 stereophotographs were of sufficient quality to detect clinically significant macular edema; 175 (84%) of the 208 stereophotographs detected foveal center thickening. The agreement between the clinician and the photographic grading, measured by weighted kappa, was 0.52 for clinically significant macular edema and 0.58 for foveal center thickening, representing fair to good agreement beyond chance. Agreement was improved when normal fundus Nidek stereophotographs were available as standards for comparison. CONCLUSIONS: The Nidek 3Dx camera is suitable for photographic detection of clinically significant macular edema and may have a potential advantage over conventional cameras by achieving good-quality, gradable stereophotographs in a large proportion of photographed eyes.