Abstract
Purpose: :
To assess changes in refraction pre and post pars plana vitrectomy (PPV) in pseudophakic eyes.
Methods: :
Retrospective case note review of pseudophakic patients undergoing PPV for a variety of vitreo–retinal disorders. Patients were excluded where there was no accurate preoperative refraction available prior to the onset of the vitreo–retinal pathology. Post operative refractions were performed three months following vitrectomy after correction of retinal pathology. Anterior chamber depths, measured using a Zeiss IOL Master, immediately pre and two months post PPV were obtained prospectively on 32 patients. Axial length, IOL type and power, time period from phacoemulsification to PPV surgery and intraocular tamponade use were also recorded. The pre and post operative refraction of the pseudophakic non vitrectomised fellow eye was used as a control where possible
Results: :
Data were obtained on 71 patients undergoing PPV. Control data were available on 37 pseudophakic fellow eyes. In the eyes undergoing PPV mean cylinder was 1.1D preoperatively and 1.1D postoperatively. Mean spherical equivalent was –0.24D preoperatively and –0.68D postoperatively (p<0.0001) representing a median myopic shift of –0.44D (range +0.75 to –2.13, SD 0.66). By comparison mean spherical equivalent in the control fellow eye group was –0.14 preoperatively and –0.12 post operatively. Anterior chamber depth did not change significantly, with mean depths of 3.29mm preoperatively and 3.27 post operatively.
Conclusions: :
Pars plana vitrectomy results in a myopic shift in refraction in some pseudophakic eyes that is not fully explained by changes in anterior chamber depth.
Keywords: refraction • vitreoretinal surgery • cataract