Clinical Features of Diabetic Macula Edema after Photocoagulation in Proliferative Diabetic Retinopathy

Objective: To analyze the clinical features of diabetic macular edema (DME) after photocoagulation in proliferative diabetic retinopathy (PDR), and to provide the foundation for further research on the treatment of DME. Methods: This retrospective cross-sectional, observational study included 30 patients (43 eyes) who conformed to the inclusion criteria of Mianyang Wanjiang Hospital from January 2015 to December 2016. The features of DME that occurred after photocoagulation for PDR were assessed by optical coherence tomography (OCT) and fundus fluorescein angiography (FFA). Eyes were divided to subgroups according to with some clinical features or not. The causes of poor visual function of DME were assessed by comparing differences of best corrected visual acuity (BCVA) between subgroups in each characteristic group by independent samples t-tests or one-way analysis of variance. Results: The mean BCVA was 3.98±0.58. Of the 43 eyes with DME, 30 (70%) were classified as moderate or severe DME. Twenty-two eyes (51%) had a cystoid cavity gap of more than 350 µm, 27 (63%) had DME in the central fovea, and 35 (81%) had destruction of the ellipsoid zone and outer limiting membrane. Seven eyes (16%) had a little serous retinal detachment under the macula, nine eyes (21%) had epiretinal membranes, and six eyes (14%) had diabetic optic neuropathy. Five of these characteristics, i.e., ellipsoid zone destruction (t=3.62, P= 0.001), DME in central fovea (t=-1.23, P=0.029), large cystoid cavity gap (t=5.49, P<0.001), severity of DME (F=17.54, P<0.001), and diabetic optic neuropathy (t=-5.56, P<0.001), significanlty affect the BCVA. Conclusions: DME occurred extensively after photocoagulation treatment for PDR. For eyes with DME, loss of BCVA was associated with the severity of the DME, ellipsoid zone destruction, DME in the central fovea, large cystoid cavity gap, and diabetic optic neuropathy. Key words: diabetic macula edema; optical coherence tomography; fundus fluorescein angiography; clinical features