Late-stage progressive corneal astigmatism after penetrating keratoplasty for keratoconus

Progressive corneal astigmatism occurring at least 10 years after penetrating keratoplasty for keratoconus is a late-phase complication of surgery. This report characterizes this condition in a series of patients from three corneal referral centers in the United States.

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 three D over baseline recorded at least 5 years later. Patients who had any other corneal or intraocular surgery performed were excluded.

Data from 15 patients (11 males and 4 females) who had penetrating keratoplasties performed by 8 different surgeons are included in this descriptive series. Postoperative follow-up averaged 17.27 years (range 11-24 years). The average donor button size was 7.83 mm (range 7.25-8.5 mm). Baseline corneal astigmatism was obtained an average of 5.2 years after penetrating keratoplasty (range 1.5-16 years) and was on average 3.57 +/- 1.8 D (10 with-the-rule [WTR], 3 against-the-rule [ATR], 2 oblique). Corneal astigmatism significantly increased to an average of 11.23 +/- 3.56 D (range 8.00-19.37 D, P < 0.0001) and most astigmatism was regular and WTR (9 WTR, 3 ATR, 3 oblique) 15.3 years (range 10-22 years) after surgery. Inferior steepening on topography was often noted, even those with oblique and ATR axes.

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.