Penetrating Keratoplasty in Asian Eyes: The Singapore Corneal Transplant Study
Presented at: Singapore Eye Research Institute–Association for Research in Vision and Ophthalmology meeting, February 2005, Singapore.
Received 29 March 2007; received in revised form 15 August 2007; accepted 31 August 2007. published online 30 November 2007.
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.
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