Assessment of Risk Factors Affecting Refractive Outcomes after Phacovitrectomy for Epiretinal Membrane

PURPOSE: To investigate factors associated with refractive outcomes after phacovitrectomy for epiretinal membrane (ERM). METHODS: Retrospective review of patients undergoing phacovitrectomy for ERM was done. The main outcome measure was predictive refraction error (PE), defined as observed refraction error – target refraction error, calculated by the SRK/T, Haigis, and SRK II formulae. PE was measured at postoperative 1, 3, and 6 months. Simple and multiple linear regression analysis were used to evaluate factors associated with PE. RESULTS: A total of 53 eyes of 53 patients were included. The mean PEs at postoperative 1, 3, and 6 months were all negative, implying myopic shift in all patients regardless of the intraocular lens formula used. Haigis formula showed the least myopic shift among the three formulae (p = 0.001, Friedman test). There was no significant difference in PE depending on preoperative central macular thickness (CMT) in subgroup analysis. On stepwise multiple linear regression analysis, ERM etiology (β = 0.759, p = 0.004, SRK/T formula; β = 0.733, p = 0.008, Haigis formula; β = 0.933, p < 0.001, SRK II formula), preoperative anterior chamber depth (β = −0.662, p = 0.013, Haigis formula; β = −0.747, p = 0.003, SRK II formula), and decrease of CMT (β = −0.003, p = 0.025, SRK/T formula) were significantly associated with PE at postoperative 6 months. CONCLUSIONS: Myopic shift in PE was observed after combined phacovitrectomy for epiretinal membrane. ERM etiology, preoperative anterior chamber depth, and decrease of CMT were significantly associated with PE at postoperative 6 months. There was no difference in PE after surgery between the two groups defined by CMT (≥500 and <500 μm).