Impact Of Imported Donor Cornea Parameters On Success Of Corneal Grafts After Penetrating Keratoplasty In A Low-Middle Income Country.

Corneal opacity is the second leading cause of visual impairment in Pakistan, highlighting the high burden of corneal disease and need for donor grafts. However, there is limited Pakistan specific data available and the country lags behind others e.g. US, India, and Sri Lanka, in terms of number of corneal transplants procedures performed and donor tissue self-sufficiency. This gap also extends to research on donor suitability factors. We aimed to investigate the impact of several donor related factors on corneal graft success, helping surgeons make informed decisions in tissue selection and establishing donor tissue retrieval standards in Pakistan.

This study was based at the ophthalmology clinic of a major tertiary care hospital in Karachi, Pakistan (The Aga Khan University Hospital).

We did a retrospective cohort study and data was collected using non-probability consecutive sampling from patient and donor record files for all PKP procedures performed (fulfilling the inclusion criteria) over the period of 5 years. 161 cases were included in the final analysis. Donor tissue characteristics as provided in the tissue report were recorded including the donor’s age, endothelial cell density, death to cornea preservation time and death to surgery time. Primary outcome was the transplanted corneal graft success. Graft success was measured by the clarity of the graft at the 6 month follow up visit as determined by a senior ophthalmologist after detailed slit lamp examination.

Cox regression analysis of graft success was performed using SPSS version 21 and none of the predictors were found to have a statistically significant relationship with the outcome (all p > 0.05). Hazard ratios near 1 suggests minimal associations between variables studied and graft success. Donor age (Exp(B) = 0.987, p = 0.305), endothelial cell density (Exp(B) = 0.999, p = 0.288), death-to-preservation time (Exp(B) = 1.000, p = 0.855), and death-to-surgery time (Exp(B) = 1.000, p = 0.529) showed no meaningful impact on graft success. Origin of eye bank (US vs Srilanka) (Exp(B) = 0.820, p = 0.712) and surgery duration (Exp(B) = 1.002, p = 0.609) also had no significant effect.

The lack of significant findings in our study suggest that the donor parameters studied did not meaningfully impact graft success. Several reasons could explain these e.g unmeasured variables or limited sample size. However, it also highlights the fact that there was no significant difference in outcomes between corneas from US vs Srilanka and increased procurement cost of corneas from US could be avoided especially in a resource constraint setting like Pakistan where majority of health-care is funded out of pocket. Our study highlights the need for further multicentre studies to help establish donor acceptability criteria for Pakistan.This will help avoid prohibitive criteria with no significant effect on outcomes in our context.