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Background
Idiopathic macular epiretinal membrane (IMEM) shows a high incidence and affects visual function of patients.The primary management of IMEM is vitrectomy, but the study on prediction of visual acuity after operation by optical coherence tomography (OCT) is seldom.
Objective
This study was to evaluate the predicting ability of OCT for preoperative visual outcome for IMEM patients who received vitrectomy.
Methods
The clinical data of IMEM patients with vitrectomy from March 2009 to May 2013 were retrospectively analyzed in People’s Hospital Peking University.Forty-nine eyes of 48 cases were divided into continuous group (19 eyes of 18 cases) and discontinuous group (31 eyes of 31 cases) based on whether the extraretinal layers were intact on OCT, including retinal pigment epithelium (RPE), inner and outer segment of photoreceptors (IS/OS) and external limiting membrane (ELM).Central foveal thickness (CFT) by high-resolution spectral-domain OCT and best corrected visual acuity (BCVA) (LogMAR) before surgery and 12 weeks after surgery were recorded and compared between the two groups, and the correlations of shift of CFT with the shift of LogMAR vision was analyzed by unitary linear regression to evaluate the value of OCT in predicting postoperative vision.Writen informed consent was obtained from each patient prior to any medical operation.Written informed consent was obtained from each patient before surgery.
Results
In 12 weeks after operation, reflective strips of RPE layer, IS/OS and ELM layer were intact in 18 eyes of the continuous group after vitrectomy.The number of eyes with discontinuous strip in RPE layer decreased to 1 eye after operation from 6 eyes before operation, and the number of eyes with IS/OS reflective strip discontinue decreased to 19 eyes after operation from 29 eyes before operation, and that with ELM layer discontinue decreased to 15 eyes after operation from before operation in the discontinuous group.The improvement of LogMAR BCVA was increased with the decline of CFT values with a negative correlation between them (R2=0.298, B=0.001, P=0.000), and postoperative LogMAR visual acuity improved 1 line whenever CFT reduced by 100 μm.LogMAR BCVA was 0.4±0.19 before surgery and 0.36±0.21after surgery in the continuous group, showing a insignificant difference between them (t=0.876, P=0.393).In the discontinuous group, the postoperative logMAR BCVA was significantly higher after operation (0.46±0.26) than 0.82±0.41 after operation (t=6.206, P=0.000).The increase value of LogMAR after vitrectomy was 0.3 in the discontinuous group, which was superior to 0.0 of the continuous group.
Conclusions
The continuity of extraretinal layers and CFT by OCT are closely associated with the improvement of vision after vitrectomy in the eyes with IMEM. Postoperative vision is better in IMEM eye with continuous retinal reflective strips before operation, and majority of IMEM eyes can improve vision after operation. Preoperative OCT seems to be an important diagnostic tool for the selection of patients who benefit or not from surgery to certain extent.