The importance of different preoperative factors in the prognosis of functional results of uncomplicated surgery for idiopathic epimacular membranes

Abstract

Purpose : to estimate the cumulative effect of different preoperative predictors on the functional results of the removal of idiopathic epimacular membranes (EMMs) 12 months after the surgery. Material and methods . 62 patients (63 eyes) with idiopathic EMMs aged 49 to 85 were operated according to the standard procedure and followed up for 12 months. The monitoring included, in addition to standard methods, Amsler grid test and optical coherence tomography of the macula. Results . Throughout the postoperative period, significant improvement in visual acuity, reduction of metamorphopsias, and restoration of both inner and outer fovea layers as well as macular thickness were observed. Twelve months after surgery, visual acuity strongly correlated with baseline visual acuity (R = 0.571, p < 0.05), the span of the defects of the external limiting membrane (ELM) (R = -0.359, p < 0.05), and interdigitation zone (IZ) defects (R = -0.394, p < 0.05). At the end of the follow-up period, metamorphopsia value correlated the most strongly with the duration of the disease (R = 0.380, p < 0.05), baseline visual acuity (R = -0.398, p < 0.05), initial metamorphopsias intensity (R = 0.271, p < 0.05), central retinal thickness (R=0.318, p<0.05) and the ectopic inner macular layers (R = 0.358, p < 0.05). A trend was observed toward the correlation between the final visual acuity and presurgical metamorphopsias severity (R = 0.248, p = 0.113), thickness of EMM (R = -0.246; p = 0.111), central retinal thickness (R = -0.203, p = 0.198) and the presence of a cystoid macular edema (CME) (p = 0.181). A correlation was also observed between metamorphopsias severity noted 1 year after surgery and the length of ELM (R = 0.222, p = 0.159) and IZ (R = 0.211, p = 0.201) defects before surgery. Regression with a 0,597-determination coefficient showed that the baseline visual acuity and central retinal thickness had the biggest impact on the visual acuity measured 1 year after surgery (p < 0.001 and p = 0.002, respectively). Conclusions . The surgery for idiopathic EMMs leads to a significant improvement in the quality of visual functions and anatomical characteristics of the macula. Restoration of outer macular layers may indicate the ability of photoreceptors to repair. The most significant preoperative predictors which determine the quality of visual functions after EMMs removal are thickness of the membrane, central retinal thickness, deformation degree of the inner foveal layers, state of photoreceptors, CME, visual acuity and metamorphopsias severity. At the same time, the baseline visual acuity and central retinal thickness had the biggest impact on the visual acuity achieved by surgery. Early surgery is reasonable, while the evaluation of both anatomical and functional results is advisable not earlier than 12 months after surgery.