Purpose: To compare long-term keratometric changes after penetrating keratoplasty (PK) for keratoconus and Fuchs endothelial dystrophy. Design: Retrospective, comparative case series. Methods: We retrospectively analyzed 168 corneas after PK for keratoconus (85 eyes of 63 subjects) and Fuchs dystrophy (83 eyes of 60 subjects). Patients were examined after final suture removal at 12 months after PK to 30 years after surgery. Operations were performed by one surgeon (W.M.B.) using the same suturing technique in all cases. Eyes were excluded from further analysis after regrafting or after relaxing incisions. Mean keratometric corneal power and astigmatism were measured by manual keratometry. Data were assessed by using generalized estimating equation models to determine change over time. Results: Mean keratometric corneal power and astigmatism increased through 30 years after PK for keratoconus (P < .001 and P < .001), but did not change through 20 years after PK for Fuchs dystrophy (P = .55 and P = .55) The change in keratometric corneal power and astigmatism after PK in keratoconus patients only differed from the change in Fuchs dystrophy patients 10 or more years after PK (P = .002 and P = .003). Conclusions: Corneal curvature and regular astigmatism increase progressively after PK for keratoconus, but remain stable after PK for Fuchs dystrophy. Our data suggest that keratometric instability after PK for keratoconus is attributable to delayed, progressive ectasia in the host corneal rim.
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