[Residual myopia after penetrating keratoplasty for keratoconus]

To study the results of penetrating keratoplasty for keratoconus analyzing the differences in ultimate spherical equivalent according to graft size and the trephine used in the recipient.

Retrospective study of 38 patients that were divided into three groups. Group A is composed of patients with a 0.50 mm donor-recipient difference, 0.25 mm in group B and same-sized in group C. In each group visual acuity, spheric equivalent, keratometry and other parameters were assessed. Statistical analysis was performed by comparing the means of the parameters evaluated.

We found a better final visual acuity in group C when compared with group A, and a lower spherical equivalent when we compared groups A with C and A with B. The results were better in those groups where the donor-recipient difference was smaller.

We believe that it is convenient to minimize the size difference between donor and recipient or to use same-sized trephines to diminish the final spheric equivalent.