The relative importance of risk factors used to define high-risk keratoplasty.

The risk factors commonly used to classify high-risk keratoplasty were studied to determine their relative importance. Survival analysis of a single-surgeon series of 702 grafts was performed using both univariate and multivariate analysis, with graft failure from rejection being the end point. The number of previously rejected grafts, the number of vascularized recipient corneal quadrants, the number of recipient stromal vessels, and the original diagnosis were highly significant factors for survival (P = 0.0001). Diseases usually associated with avascular corneas, such as keratoconus, fared best, whereas diseases causing vascularization had a poor diagnosis. Old interstitial keratitis had a good prognosis, indicating that ghost vessels are not a risk factor. Although a previously rejected graft was a significant risk factor, this was only true in vascularized recipients. There was no significant difference in survival between repeat grafts into avascular corneas and first-time grafts into avascular corneas, indicating that it is the vascularization associated with rejection that confers the increased risk. Multivariate analysis indicated that the number of vascularized quadrants (P = < 0.0001), the number of vessels (P = < 0.0001), and a previously rejected graft (P = 0.0002) were risk factors for graft survival but that patient age was not a significant risk factor (P = 0.9). Three distinct survival groupings were evident, namely, avascular corneas, corneas with 1-2 quadrants or 1-15 vessels, and corneas with 3+ quadrants of vascularization or 16+ vessels. This would seem a reasonable basis for classifying recipient corneas into low-, intermediate- and high-risk cases.