Optical coherence tomography classification of diabetic cystoid macular edema

To propose a new classification of diabetic cystoid macular edema (CME) based on optical coherence tomography (OCT) findings and cover all new important findings. A retrospective study was carried out in the El-Minia Investigation Eye Center between January 2012 and November 2012. It included 104 eyes of 86 patients, aged between 50 and 71 years, all with type II diabetes mellitus of duration from 5 to 20 years. All patients were diagnosed to have CME, as assessed by OCT, with measurement of the vertical size of the largest macular cyst and maximum macular thickness, and the relation between them. Patients were divided into four groups. Eyes with cysts less than 30% of macular thickness were considered to have CME I (n = 4, 3.84%), while those between 30% and 60% were considered to have CME II (n = 62, 59.62%). Eyes with cysts between 60% and 90% of macular thickness were considered to have CME III (n = 36, 34.62%). CME IV was diagnosed when the size of the cyst became more than 90% of the macular thickness, and this was encountered in two eyes (1.92%). OCT is a useful technique for quantitative measurement and helps in better anatomical characterization of CME, and this classification of diabetic CME may be of value in classification of CME due to causes other than diabetes.