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Purpose : To elucidate the characteristics and risk factors of keratoconus (KC) progression and recurrence over long term after penetrating keratoplasty (PK) using anterior segment optical coherence tomography (AS-OCT).
Methods : Retrospective chart review was performed on patients maintaining clear grafts over 10 years after PK, among who visited the University of Tokyo Hospital from December 2015 to February 2016. Patients were divided into 2 groups based on their primary indication of PK (KC and Others group). AS-OCT parameter analyzed were central corneal thickness (CCT), inferior graft thickness (IGT), inferior host thinnest part corneal thickness (IHT), graft diameter (GD), anterior chamber depth (ACD), and keratometric powers including steepest keratometric power (Ks), maximum keratometrtic power (Kmax). Patient factors (sex, age at PK, postoperative years, current age and GD) explaining corneal ectasia parameters (IHT/CCT, IGT/CCT and ACD) and corneal ectasia parameters explaining keratometric values were obtained by regression analysis stepwise methods in each group.
Results : Total 92 eyes were enrolled (KC N=46, Others N=46). Mean Age at PK, postoperative years, GD, ACD, IHT/CCT, IGT/CCT, Ks and Kmax in KC and Others group were, 29.5 and 44.6 years old (p<0.0001), 27.6 and 25.4 years (p=0.286), 7.0 and 7.3 mm (p=0.0368), 3.65 and 2.97 mm (p<0.0001), 0.92 and 1.11 (p=0.0016), 1.03 and 1.10 (0.0891), 57.5 and 51.6 D (p=0.0005), and 67.7 and 59.5 D (0.0032), respectively. Regression analysis revealed that graft diameter was associated to corneal thinning and corneal protrusion and host corneal thinning was related to keratometric values such as Ks and Kmax in KC group. Corneal thinning was related to age at PK and keratometric values were related to ACD in Others group.
Conclusion : Keratoconic eyes develops both graft and host thinning around graft-host junction over long term after PK. Small graft diameter was a risk factor for recurrent KC.
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