Long-term changes in corneal surface configuration after penetrating keratoplasty

Abstract

Purpose: To examine the long-term longitudinal changes in corneal surface configuration as determined by Fourier series harmonic analysis of videokeratography data and of visual acuity and refraction after penetrating keratoplasty (PK).

Design: Interventional case series.

Methods: One hundred thirty eyes of 130 consecutive patients who were scheduled for PK using 16 interrupted 10-0 nylon sutures were recruited. Spherical equivalent power, regular astigmatism component, irregular astigmatism (asymmetry and higher-order irregularity) component of the central cornea as determined by Fourier analysis of videokeragraphic data, spectacle-corrected visual acuity, and spherical equivalent were examined at 1 week, and at 1, 3, 6, 9, 12, 18, and 24 months after PK.

Results: Spherical equivalent power increased considerably for up to 1 month after PK, but thereafter showed no further appreciable change up to the final follow-up at 24 months. The regular astigmatism component decreased markedly for up to 6 months after PK, while the total irregular astigmatism (sum of the asymmetry and higher-order irregularity) component decreased considerably up to approximately 3 months, and then these showed no further relevant change for up to 24 months. Spectacle-corrected visual acuity also improved markedly until approximately 3 months after PK, after which it was virtually stable. Furthermore, important correlations were found between regular and irregular astigmatism and the spectacle-corrected visual acuity.

Conclusions: Corneal surface configuration after PK appears to be stable by approximately 6 months after PK, concurrent with postkeratoplasty stabilization of visual acuity.