Effects of penetrating keratoplasty suture removal on corneal topography and refraction

Purpose. To study the refractive and topographic modifications induced by p enetrating keratoplasty suture removal. Methods. We retrospectively studied 50 corneas from 50 patients who had undergone penetrating keratoplasty. Al l of the eyes were examined before and after all sutures were removed at 10 .8 +/- 4.7 months and 20.3 +/- 7.9 months after keratoplasty. Subjective re fraction, best spectacle-corrected visual acuity (LogMAR units), and cornea l topography (EyeSys 2000R device) were recorded. Results, Suture removal d ecreased the subjective cylinder by an average of 0.91 +/- 2.32 D (p = 0.00 9 and modified the corneal topographic pattern (p = 0.03) and shape (p < 0. 001) distribution. The change in subjective cylinder correlated with the Va riation of the steepest meridian power (r(s) = 0.46; p < 0.001). It correla ted with the change in topographic pattern (r(s) = 0.59; p < 0.001). The su bjective spherical equivalent increased (hyperopization) by an average of 0 .61 +/- 2.24 D (p = 0.01). After suture removal, the prolate shape was less frequent, and the oblate shape was more frequent than before suture remova l. Best spectacle-corrected visual acuity increased by an average of 0.8 +/ - 2.0 lines (p = 0.004). The change in subjective cylinder correlated with the change in visual acuity (r(s) = 0.36; p = 0.006). Conclusion. Suture re moval modifies the corneal topographic pattern and shape. It decreases the subjective cylinder and induces an hyperopization. Visual-acuity improvemen t after suture removal mainly is explained by the decrease in astigmatism. Suture removal seems particularly helpful in corneas with a bow-tie pattern .