Outcomes of penetrating keratoplasty in keratoconus

Keratoconus (KCN) is one of the most common indications of corneal transplantation in Iran. This study was conducted to determine the outcomes of penetrating keratoplasty (PK) for KCN in patients operated in a private practice setting from 1994 to 2001.

This longitudinal retrospective study included 164 eyes of 164 patients. Variables included preoperative keratometry, trephination and suturing techniques, donor-recipient disparity, surgical complications, immunologic rejection, graft clarity, postoperative spherical and cylindrical refractive error, keratometry, uncorrected and best spectacle-corrected visual acuity, suture management, and the results of keratorefractive procedures.

Patients were followed for a mean period of 33.5 months. Mean postoperative best spectacle-corrected visual acuity (BSCVA) at last follow-up was 0.14 +/- 0.11 LogMAR (20/25); mean spherical error and mean corneal astigmatism were -0.61 +/- 2.6 and 3.4 +/- 1.8 D, respectively. Final visual outcomes were not significantly correlated with trephination and suturing techniques or severity of the ectasia. Although donor-recipient disparity did not affect final astigmatism, more myopic shift was observed with greater disparity, but this finding was not of statistical significance. Overall, 26.8% of the patients required keratorefractive surgery, which resulted in 2.9 D reduction in corneal astigmatism. Immunologic graft rejection occurred in 28% of cases; however, all episodes responded to medical management, and none resulted in graft failure.

Penetrating keratoplasty is a safe and effective procedure with remarkable optical and visual outcomes for patients with keratoconus who are contact lens intolerant or have unacceptable corrected visual acuity. Neither severity of the disorder nor trephination and suturing techniques significantly affects final visual outcomes. Less graft-recipient disparity (0.25 versus 0.50 mm) seems to induce less myopic shift.