Late Stage Progressive Corneal Astigmatism after Penetrating Keratoplasty for Keratoconus

Abstract

Abstract: : Purpose: Late stage, progressive, corneal astigmatism after corneal transplantation for keratoconus, to our knowledge, has not been previously described. This study characterized this condition in a series of patients from three corneal referral centers in the United States. Methods: Charts were retrospectively reviewed which met the following criteria: penetrating keratoplasty performed for keratoconus at least 10 years ago, keratometry or simulated keratometry from topography as well as manifest refraction recorded at least 6 months after the last suture removal ("baseline"), and an increase in corneal astigmatism of at least 3 D over baseline recorded at least 5 years later. Patients who had any other corneal or intraocular surgery performed were excluded. Results: Data from 12 patients (10 males and 2 females) who had penetrating keratoplasties performed by 6 different surgeons were included in this descriptive series. Post-operative follow-up averaged 15.8 years (range 10-23 years). The average donor button size was 7.78 mm (range 7.25-8.5 mm). Baseline corneal astigmatism was obtained an average of 5.6 years after penetrating keratoplasty (range 2-16 years) and was on average 3.74 D (8 with-the-rule (WTR), 2 against-the-rule (ATR), 2 oblique). Corneal astigmatism increased to an average of 12.01 D (range 8.12-19.37 D) and most astigmatism was regular and WTR (8 WTR, 2 ATR, 2 oblique) 14.6 years (range 10-23 years) after surgery. Inferior steepening on topography was often noted, even those with oblique and ATR axes. Conclusions: High, late stage, regular astigmatism after penetrating keratoplasty for keratoconus is described in a series of patients occurring at least 10 years after surgery. Possible mechanisms of this progressive astigmatism are recurrence of keratoconus in the graft, progressive corneal thinning of the host cornea, or progressive misalignment of the graft-host interface over time.

Keywords: cornea: clinical science • keratoconus • topography