Late changes in refraction, pachymetry, visual acuity, and corneal topography after penetrating keratoplasty

To analyze the late changes in refraction, corneal topography, and pachymetry after penetrating keratoplasty.

We have retrospectively analyzed data of 64 eyes of 56 patients with a clear corneal graft and no other ocular diseases. The eyes were examined soon and several years after all sutures were removed, at 19.5 +/- 3.1 months and 76.8 +/- 25.2 months, respectively, after keratoplasty. All eyes were examined using the EyeSys 2000 videokeratograph and the Tomey SP2000 ultrasonic pachymeter. Corneal surface regularity was studied using the indices provided by the Holladay Diagnostic Summary (ie, asphericity coefficient Q; corneal uniformity index CU; predicted corneal acuity PCA). Irregular astigmatism was quantified using semimeridian data from videokeratographs (refractive power symmetry index).

Visual acuity increased by an average of 0.35 +/- 0.93 lines (P = 0.002) between the 2 examinations, whereas no significant changes in refraction and videokeratoscopy (ie, power, indices, and irregular astigmatism) were observed (P > or = 0.08). Central corneal thickness significantly increased from 542 +/- 31 microm to 572 +/- 38 microm (P < 0.001). Change in BSCVA did not significantly correlate with the change in refraction, in topographic indices, or in irregular astigmatism (rs < or = 0.13; P > or = 0.16).

Late after penetrating keratoplasty, best corrected visual acuity shows a small but statistically significant improvement, whereas refraction and corneal surface regularity are stable. This late improvement in visual acuity is not explained by current techniques.