Penetrating keratoplasty in Asian eyes: the Singapore Corneal Transplant Study

Abstract

Purpose: The Singapore Corneal Transplant Study (SCTS) is a 16-year prospective study of 2100 consecutive corneal transplants performed between January 1991 and November 2006 in patients from Southeast Asia at a single tertiary center. The indications, complications, long-term survival rates, and risk factors for graft failure of penetrating keratoplasty (PK) performed in Asian eyes are reported.

Design: Prospective cohort study.

Participants: Of the 2100 corneal transplants, 1130 consecutive PKs were performed from January 1991 to December 2003. One graft per patient was selected, leaving 901 grafts for analysis.

Methods: Data were obtained from the Singapore Eye Bank's SCTS database. Cases were classified into optical, therapeutic, and tectonic indications and 9 corneal disease groups. Twenty-four demographic, preoperative, intraoperative, and donor risk factors were subjected to Kaplan-Meier survival analysis, univariate analysis, and multivariate analysis by Cox proportional hazards regression modeling.

Main outcome measure: Graft failure, defined as the irreversible loss of optical clarity.

Results: Study patients were Asian, comprising Chinese (72.7%), Indian (11.54%), and Malay (11.1%) ethnicities (mean age, 56.65 years). The mean follow-up period was 36.8+/-35.5 months. Indications for surgery were optical (87.0%), therapeutic (8.1%), and tectonic (4.88%). Main diagnoses were pseudophakic/aphakic bullous keratopathy (23.4%), postinfectious scarring (12.9%), regrafts (12.4%), keratoconus (9.7%), and posttraumatic scarring (7.3%). Kaplan-Meier survival rates for optical grafts were 86.6%, 72.0%, 63.7%, and 52.0% at 1, 3, 5, and 10 years, respectively; survival rates for therapeutic grafts were 78.4%, 58.3%, and 37.3% at 1, 3, and 5 years, and those for tectonic grafts were 68.3% and 41.7% at 1 and 3 years. Endothelial rejection and late endothelial decompensation accounted for 50.51% of failures. Multivariate analysis revealed 9 predictors for graft failure: recipient gender, age, graft size, graft endothelial status, primary corneal disease, glaucoma, inflammation, perforation, and corneal vascularization.

Conclusions: The long-term outcome for optical indications in Asian eyes follows a trend in endothelium-related attrition similar to that seen in the West. Tectonic and therapeutic keratoplasty for corneal infections and perforation, however, constitute a significant proportion of corneal transplantation performed in Asia and carry a graver prognosis in terms of graft survival.