Purpose:
To compare long-term keratometric changes after penetrating keratoplasty (PK) in eyes with keratoconus to those in eyes with Fuchs’ endothelial dystrophy.
Methods:
We performed a longitudinal cohort study of 166 PKs for keratoconus (84 eyes of 68 subjects) and Fuchs’ dystrophy (82 eyes of 59 subjects) followed for up to 30 years after surgery. All operations were performed by one surgeon using the same double running suture technique. Eyes were excluded from further analysis after re-grafting or after relaxing incisions for astigmatism. Final suture removal was at 12 months after PK in all cases. The change in mean keratometry between 13 months and 30 years after PK was calculated for keratoconus and Fuchs’ dystrophy eyes. Data were assessed and compared by using generalized estimating equation (GEE) models. Models were assessed to determine if the slopes over time were significant within groups or different between groups.
Results:
Over the entire study period, mean keratometry increased in keratoconus (P<0.001) and was unchanged in Fuchs’ dystrophy (P=0.89). Between 13 months and 10 years after PK, mean keratometry increased a small, but significant amount in keratoconus (P=0.04) and Fuchs’ dystrophy (P=0.05). Beyond 10 years after PK, mean keratometry continued to increase in keratoconus (P<0.001), but was unchanged in Fuchs’ dystrophy (P=0.16). When comparing keratoconus to Fuchs’ dystrophy, the change in mean keratometry was not different for 10 years after PK (P=0.63), but was different beyond 10 years after PK (P=0.01).
Conclusions:
Mean keratometry increases for up to 30 years after PK for keratoconus, but remains unchanged at 20 years after PK for Fuchs’ dystrophy. The increase in mean keratometry in keratoconus is significantly greater than that in Fuchs’ dystrophy only beyond 10 postoperative years. Late-onset corneal steepening found in penetrating grafts for keratoconus may be a manifestation of progressive ectasia.
Keywords: keratoconus • cornea: clinical science • clinical (human) or epidemiologic studies: outcomes/complications