Abstract
Purpose :
Phacoemulsification combined with Descemet’s Stripping Endothelial Keratoplasty (DSEK triple) is now a routinely performed procedure. There is a known hyperopic shift that occurs in the postoperative period, and studies advocate a standard myopic target of -1.00 to -1.25 diopters to achieve emmetropia. Preoperative central corneal thickness is not routinely considered in surgical planning. This study investigates the impact of preoperative central corneal thickness on the predicted postoperative spherical equivalent in patients undergoing DSEK triple.
Methods :
Retrospective review from January 2011 to May 2016 of 56 eyes of 55 patients that underwent uncomplicated DSEK triple for cataract and Fuchs’ dystrophy. Eyes had no previous history of surgery. There were no subsequent procedures. Surgery was performed using a clear-corneal, temporal approach. Lenses were implanted inside the capsular bag. Ultrasonographic pachymetry was obtained on the same day as optical biometry. Axial length, average keratometry values, and predicted postoperative spherical equivalent were recorded. Manifest spherical equivalents were recorded at 3-6 months postoperatively. A univariate analysis comparing the difference between the predicted and measured postoperative spherical equivalent (refractive delta) and pachymetry was performed. Scatterplot and chi-square analyses was used to determine a cutoff preoperative pachymetry which was associated with a postoperative spherical equivalent within 0.5 diopters of predicted.
Results :
The average refractive delta at 3-6 months was 1.105D +/- 1.042D. Univariate analysis of pachymetry versus the refractive delta revealed a Pearson Correlation of 0.432 (p=0.001), indicating that lower pachymetry values had a statistically significant correlation with smaller refractive deltas. Scatterplot and chi-square analysis identified a cutoff of 600microns as being significantly associated with a spherical equivalent within 0.5D of the intended (p=0.001).
Conclusions :
Research has suggested that surgeons should target 1 to 1.25 diopters of myopia for emmetropia after DSEK triple. A thicker cornea induces more hyperopia, according to the thick lens equation. The results of this study suggest that refractive outcomes are closer to target in thinner corneas. Prospective studies are needed to determine a suitable myopic target for thicker corneas.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.