Refractive change after pars plana vitrectomy

PurposeThis study investigated the changes of refractive status in both phakic and pseudophakic eyes after pars plana vitrectomy (PPV) surgery without scleral buckling or silicone oil tamponade, and examines the possible factors that may affect the refractive changes.MethodsA retrospective case note review of 172 eyes (172 patients) undergoing PPV surgery for a variety of vitreoretinal conditions. Refractive status was measured before and after vitrectomy surgery in 60 eyes after the application of inclusion and exclusion criteria. Refractive status before and after PPV was analyzed using paired t-tests. An independent t-test and analysis of variance were subsequently conducted to analyze any significant differences in refractive change under a variety of etiological factors. Changes in refraction were also analyzed using a linear regression model.ResultsA total of 60 eyes from 60 consecutive patients were included in this study. The mean spherical equivalence (SE) before PPV was 0 diopters (D), and −1.21 D after PPV. The mean change of SE was −1.21 D (95% confidence interval −1.70 to −0.71 D, p < 0.001). The mean astigmatism (cylinder) power before PPV was −1.17 D, and was −1.23 D after PPV. The mean change of astigmatism was −0.06 D (p = 0.753). There was no significant difference in refractive change between gender, age groups, disease categories, and use of gas tamponade. There was a significant difference between the phakic and pseudophakic groups (p = 0.047). The mean change of SE in 37 phakic eyes was −1.60 D (95% confidence interval −2.35 to −0.85 D, p < 0.001), and in 23 pseudophakic eyes it was −0.59 D (95% confidence interval −0.99 to −0.18 D, p = 0.007).ConclusionsSignificant changes in refractive status were observed in patients undergoing PPV. Most of the patients experienced a myopic shift, among both phakic (−1.60 D) and pseudophakic (−0.59 D) patients. Changes in astigmatism were not significant. There are several plausible explanations; however, the true underlying etiologies of the refractive change are to be further investigated. To our knowledge, this is the first refractive study conducted after PPV among the Taiwanese population.