Abstract
Purpose: :
To clarify the influence of death–to–preservation interval on overall corneal graft survival as measured by corneal thickness and rejection events after penetrating keratoplasty.
Methods: :
We performed a retrospective chart review on 432 keratoconus patients that had received PKP between 1993 and 2003. Inclusion criteria: at least 2 years of follow–up as well as 2 central corneal thickness (CCT) measurements at the following time points: 3 months, 6 months, 1 year, 2 years and 5 years. Other parameters gathered included recipient age, race, sex, donor age, cause of donor death, death–to–preservation time (DtPT), death–to–surgery time, corneal thickness and cell count. A multivariate analysis was performed using donor age, death to preservation interval and cell count as independent variables. CCT and best corrected visual acuity (BCVA) at 3 months, 6 months, 1 year, 2 years and 5 years were then correlated with these indices.
Results: :
129 keratoconus patients that received PKP fit our inclusion criteria. For the 3 month, 6 month, 1 year and 2 year time points, a higher cell count correlated more strongly with a lower CCT than either DtPT or donor age (ANOVA: p = 0.029, p = 0.054 for 3 and 6 months respectively). Adjusted R Square = 0.048, suggesting that although the variables indeed had and effect on corneal thickness; this effect was a small one. At the earlier time points, BCVA had no significant correlation with DtPT. However, five years after PKP there was a highly negative correlation between DtPT and BCVA (Zero order correlation: –0.582, p = 0.002). Finally, rejection events were analyzed. Events occurred in 29.5% of the 129 total grafts. There was a weak correlation between DtPT and the chances of graft rejection by T–Test (0.333).
Conclusions: :
Cell count proved to have a higher correlation with a more favorable corneal thickness when compared with donor age and death to preservation interval. Although no association was present initially with BCVA, at 5 year follow–up a significant correlation existed between a better BCVA and a shorter DtPT. Surprisingly, no significance was shown between DtPT and the development of a graft rejection. Finally, initial data suggest that DtPT has a weak correlation with overall corneal thickness. A future study with a larger cohort of patients will allow us to know the extent of this significance.
Keywords: keratoconus • transplantation • clinical (human) or epidemiologic studies: risk factor assessment