A comparison of two selective interrupted suture removal techniques for control of post keratoplasty astigmatism

Two selective interrupted suture removal techniques were compared to determine which technique resulted in earliest, best visual acuity and least postoperative astigmatism.

Sixty-five consecutive optical penetrating keratoplasties were performed using 12 interrupted 10-0 nylon sutures and a 12-bite continuous 10-0 nylon suture, and were alternately assigned to 1 of 2 selective suture removal groups. All patients had refraction, keratometry, and videokeratoscopy postoperatively, starting at 6 weeks. Six weeks postoperatively, Group I underwent simultaneous removal of six alternate sutures, with the first of the 6 sutures removed at the steepest meridian, while Group II had selective sutures removed only at the steepest meridian, if associated with greater than 2 diopters of astigmatism in that meridian. Subsequently, interrupted sutures were then selectively removed until the resultant astigmatism approached 3.0 diopters or less. Measurements of resultant astigmatism are reported prior to selective suture removal, following selective suture removal, at 6 months postoperatively, at the completion of all selective suture removal, and at the final visit.

At 6 months, residual astigmatism after the 2 techniques of selective suture removal, as measured by refraction, keratometry, and computer-assisted videokeratoscopy, was 2.8, 3.0 and 3.4 diopters for Group I, and 2.2, 2.6 and 3.7 diopters for Group II. At 1 year, the average final visit, astigmatism was 2.5, 2.4 and 2.7 diopters for Group I, and 2.1, 2.0 and 2.3 diopters for Group II. By the final visit, a best corrected vision of 20/50 or better was achieved in 86% of eyes in Group I and in 65% of eyes in Group II, and there was a significant difference in average keratometry of 47.4 diopters in Group I compared to 46.0 diopters in Group II and, as measured by videokeratoscopy, 47.9 diopters in Group I compared to 45.8 diopters in Group II.

Selective suture removal by either technique reduces keratoplasty astigmatism with residual interrupted and continuous sutures in place. The combined use of refraction, keratometry, and videokeratoscopy probably provides more reliable and reproducible quantitative measurements of astigmatism. Minimizing astigmatism by selective suture removal is a major factor in the attempt to achieve excellent and visual function in the majority of patients who have undergone penetrating keratoplasty.