Postoperative Refractive Error of Secondary Intraocular Lens Implantation After Simultaneous Vitrectomy and Lensectomy

Abstract

Purpose: : It is generally agreed that the power of a intraocular lens (IOL) in the sulcus must be decreased slightly because of its more anterior placement, and consequently its increased "effective power" leads to postoperative actual refraction to a myopic shift (about 0.3 to 0.5 diopters). This study was performed to determine postoperative refractive errors of secondary IOL implantation after simultaneous vitrectomy and lensectomy.

Methods: : The study was performed in 42 eyes of 42 patients following secondary IOL implantation fixed in the sulcus after simultaneous vitrectomy, phacoemulsification and aspiration (PEA). Controls were 138 eyes of 124 cataract patients who underwent PEA and IOL implantation. Expected refractive error was calculated using the SRK II method, and actual refractive error was measured postoperatively. Student’s t–test was used for statistical analysis.

Results: : The expected refraction in spherical equivalents was –0.38±1.94 diopters (average±SD) for the study group and –0.67±0.97 diopters for the control group. The actual refraction after surgery was –1.21±2.14 diopters and –0.66±1.19 diopters, respectively. The spread between expected and actual postoperative refractions (actual refraction – expected refraction) was –0.81±0.86 diopters for the study group and +0.01±0.91 diopters for the control group. The difference between these two values was 0.82 diopters, which was statistically significant (p<0.001; Student’s t–test).

Conclusions: : The precise mechanism responsible for the greater spread between expected and actual refractions of this study group beyond expectation is unknown. However, clinicians should be aware of this large myopic shift in cases with secondary IOL implantation after simultaneous vitrectomy and PEA.

Keywords: intraocular lens • vitreoretinal surgery • refractive error development