Refractive change following pseudophakic vitrectomy: a retrospective review

Background: To assess the occurrence and magnitude of refractive change in pseudophakic eyes undergoing pars plana vitrectomy without scleral buckling and to investigate possible aetiological factors. Methods: Retrospective case note review of pseudophakic eyes undergoing pars plana vitrectomy for a variety of vitreo-retinal conditions over a three-year period. Anterior chamber depth was measured before and after vitrectomy surgery in 32 eyes. Thirtyseven fellow pseudophakic eyes were used as controls. Results: Eighty-seven eyes (84 patients) were included in the study. Mean spherical equivalent refraction prior to vitrectomy was –0.2 dioptres, which changed to a mean of -0.65 dioptres postoperatively (SD of refractive change +/0.6 , range 0.75 to –2.13 dioptres) (p<0.001). Sixty-one of the 87(70%) eyes experienced a myopic shift and 45(52%) eyes had a myopic shift of –0.5 dioptres or more. Mean fellow eye refraction was –0.14 dioptres preoperatively and –0.12 dioptres postoperatively (p=0.51)(n=37) Mean anterior chamber depth preoperatively was 3.29mm and postoperatively 3.27mm (p=0.87) (n=32) and there was no correlation between any pre, intra and postoperative factors examined and the refractive change observed. Conclusion: Significant persistent refractive changes occur in some pseudophakic patients undergoing pars plana vitrectomy. The mean change observed was a small myopic shift but the range was large. The aetiology of the refractive change is uncertain.