Corneal graft curvature change after relaxing incisions for post-penetrating keratoplasty astigmatism

摘要

Purpose: To evaluate change in graft steepness after graft refractive surgery (GRS) consisting of relaxing incisions with or without counterquadrant compression sutures and discover the existing influential factors. Methods: In this retrospective study, 78 eyes of 76 patients who had received penetrating keratoplasty for keratoconus underwent GRS because of high post-penetrating keratoplasty astigmatism. Any shift in graft curvature was calculated using the keratometric coupling ratio (CR; the ratio of flattening of the incised meridian to steepening of the opposite meridian). Multiple regression analysis was used to investigate the possible effect of age, graft curvature, number of incisions, use of compression sutures, achieved vector astigmatic correction, and total arc length on CR. Results: Mean patient age was 30.1 ± 10.3 years and mean follow-up period after GRS was 40.1 ± 29.0 months. There was a significant increase in average keratometry from 44.79 ± 2.08 diopters (D) preoperatively to 45.65 ± 1.86 D postoperatively (P < 0.001). Mean keratometric CR was 0.62 ± 1.09. Keratometric CR was significantly associated with patient age (R = 0.53, P = 0.04) and preoperative average keratometry (R = 0.61, P = 0.02). However, keratometric CR failed to show any significant correlation with other variables. Conclusions: A significant increase in graft steepening occurred after GRS, averaging 0.86 D. When both GRS and cataract extraction or phakic intraocular lens implantation are indicated, a staged approach (first GRS followed by phacoemulsification, for example) is advocated to calculate intraocular lens power with accuracy.