Relaxing incisions with compression sutures for control of astigmatism after penetrating keratoplasty

Ten per cent of patients with persisting postoperative astigmatism following penetrating keratoplasty (PK) require surgical re-intervention, despite an otherwise "successful" transplant. Relaxing incisions (RIs) in combination with compression sutures seem to be the preferable procedure. However, poor predictability and lack of long-term experience complicate the issue. Here we report the 2-year follow-up results of 25 patients with high PK astigmatism treated by means of RIs and compression sutures. Commonly, free-handed RIs were placed at the graft-host interface and 10-0 nylon compression sutures were placed perpendicular to the incisions. PK sutures had been removed no less than 4 months prior to refractive surgery. Nineteen eyes regained a functional vision of > or = 0.4. The net decrease in astigmatism was 6.1 +/- 4.3 D (47 +/- 21%). The mean vector-corrected change in astigmatism was 13.1 +/- 5.7 D. Cylinder axis variation was reasonably low, with a correlation of attempted versus achieved axis of r = 0.85. Within the first 3 months after operation the induced astigmatism regressed by, on average, 5.5 +/- 4.3 D, making intraoperative overcorrection necessary. As an inevitable side effect, refractive procedures resulted in a myopic shift (4.7 +/- 6.9 D) in spherical equivalence. RIs and compression sutures are very useful in reducing postkeratoplasty astigmatism if correction of extremely high cylinder (> 10 D) is not intended. However, predictability still remains unsatisfactory and more than one operation may be required.