Differential effects of primary disease and corneal vascularisation on corneal transplant rejection and survival.

Aims: To investigate the relative risk of pretransplant corneal vascularisation on rate of rejection and graft failure within 5 years of surgery when categorised by indication for transplantation.We analysed all adults recorded in the UK transplant registry who had a first cornea transplant for keratoconus (KC), pseudophakic bullous keratopathy (PBK) or previous infection (viral/bacterial/fungal/protozoan) between 1999 and 2017. We analysed the number of quadrants of the recipient cornea vascularised before transplant and type of vascularisation, the interval post-transplant to rejection, if any, and the outcome at 5 years post-transplant. Risk factors for rejection and transplant failure were modelled by multivariable risk-adjusted Cox regression.
Results: Corneal vascularisation was recorded in 10%, 25% and 67% of patients with KC, PBK and infection, respectively. Individuals with PBK had an increased hazard of transplant rejection only when there were more than two quadrants of vascularisation (HR 1.5, p=0.004) when either superficial and/or deep vascularisation was present (HR 1.3 and 1.4, respectively, p=0.004). Individuals who had a transplant for previous infection had an increased hazard of rejection with four quadrants of vascularisation (HR 1.6, p=0.003). There was no risk-adjusted increase in transplant failure associated with vascularisation in any group. There was weak evidence of reduction in risk of rejection and/or failure associated with lamellar compared with penetrating transplantation in KC and PBK in vascularised recipient corneas.
Conclusion: Vascularisation is a risk factor for corneal allograft rejection within 5 years. The indication for transplantation has a clinically significant effect on the magnitude of this risk.
Competing Interests: Competing interests: None declared.
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