Wedge resection for high astigmatism after penetrating keratoplasty for keratoconus: refractive and histopathologic changes.

PURPOSE

To analyze the refractive, topographic, keratometric changes and the histopathologic findings after wedge resection to correct high astigmatism after penetrating keratoplasty for keratoconus.

MATERIALS AND METHODS

A retrospective study was done analyzing the following parameters preoperatively and at 1, 3, and 5 years postoperatively: uncorrected visual acuity, best-corrected visual acuity, and spherical equivalent and refractive, topographic, and keratometric cylinder measures. We also studied the efficacy and safety indices, as well as the histopathologic findings of tissues submitted for pathology.

RESULTS

A total of 22 eyes of 21 patients who underwent wedge resection in the host corneal tissue for correcting high irregular astigmatism after penetrating keratoplasty for keratoconus were included in the study. Mean follow-up time from penetrating keratoplasty to wedge resection was 18 years, whereas the mean follow-up time after wedge resection was 39.04 months (range, 12-280 months). The mean preoperative refractive, topographic, and keratometric cylinders were 11.58 +/- 3.52 diopters (D) (range, 4.5-20 D), 10.88 +/- 5.03 D (range, 2.58-21.3 D), and 11.29 +/- 4.33 D (range, 4.50-18 D), respectively. The mean postoperative refractive, topographic, and keratometric cylinders at 3 years were 4.91 +/- 2.48 D (range, 0.50-10 D), 3.38 +/- 2.10 D (range, 2.05-7.1 D), and 5.31 +/- 2.90 D (range, 0.50-9 D), respectively. The percentage of correction at 3 years of follow up was 57.5% for refractive cylinder, 68.97% for topographic cylinder, and 53.01% for keratometric cylinder. All refractive, topographic, and keratometric data showed the lowest degree of astigmatism at 3 years postoperatively, with a tendency toward regression at 5 years postoperatively. Safety index was 1.0, whereas efficacy index was 0.49. All histopathologic sections of resected tissue were consistent with keratoconus progression in the host peripheral cornea.

CONCLUSION

Wedge resection is a safe and moderately effective procedure in the correction of high astigmatism after penetrating keratoplasty for keratoconus. Histopathologic changes confirm a true late progression of the disease in the host cornea. Keratoconus may be a disease that affects the entire cornea, and surgical resection does not cure the disease.