Long-term follow-up of a single continuous adjustable suture in penetrating keratoplasty

Penetrating keratoplasty was performed on 30 patients using a single adjustable continuous 10/0 nylon suture. Seventeen patients had astigmatism of 4.00 dioptre cylinders (DC) or more and were adjusted. The latest adjustment was at 32 weeks. Following adjustment there was a significant reduction in median post-keratoplasty astigmatism from 6.00 DC to 2.50 DC (p < 0.001). Thirteen patients, with astigmatism of 4.00 DC or less, were not adjusted. Median astigmatism for the non-adjusted group was 3.00 DC and for the entire group was 2.88 DC. Long-term refraction and suture status were monitored with time. Mean follow-up was 112 weeks (range 53-170 weeks). Over the study period the entire group showed significant 'long-term astigmatic drift' (LTAD), from 2.88 DC to 3.25 DC (median drift, 1.25 DC; range, 0.00-5.50 DC) (p < 0.001). Suture adjustment and suture removal showed no significant effect on LTAD. With suture removal between 32 and 84 weeks median LTAD was 1.50 DC. For suture removal after 84 weeks, median LTAD was also 1.50 DC, but the range of LTAD was 1.50 DC, compared with a larger range of 5.00 DC in the earlier suture removal group. The technique of single continuous adjustable sutures for penetrating keratoplasty is safe, effective in reducing astigmatism, but may need modification to further enhance long-term refractive stability.