Abstract
Purpose:
To investigate the effect of surgical experience on clinical outcome following deep anterior lamellar keratoplasty (DALK) and compare clinical outcomes with that following penetrating keratoplasty (PKP) undertaken for keratoconus.
Methods:
Graft survival data were analysed by Kaplan Meier survival analysis and Cox proportional hazards regression model using data from the UK transplant registry March 1999 to April 2010. Graft survival, best correct visual acuity (BVCA) and refractive error were analysed according to the number of DALK procedures a surgeon had undertaken. Graft survival for all surgeons who had undertaken at least 50 PKP prior to undertaking DALK was analysed according to the number of DALK procedures a surgeon had previously undertaken, grouped in increments of 10 procedures e.g. 1-10 to 120-131 and >131 DALK. This was first investigated collectively stratifying all surgeons within these intervals and then for individual surgeons who had performed more than 50 DALK. In addition to graft survival, visual acuity and refractive error outcome were also analysed with respect to surgeon experience.
Results:
4521 patients had undergone a PKP or DALK for keratoconus. Overall 5 year graft survival was 92% (95% CI 90-92) and 90% (95%CI 88-92%) for DALK p=0.09%. Five year graft survival was 93%, 91% and 92% following PKP, and 90%, 92% and 88% following DALK, for transplants undertaken in the periods 1999-2002, 2002-2005 and 2005-2007, respectively. Surgeon experience had no significant effect on clinical outcome following DALK. Ocular surface disease, however, was a significant risk factor for graft failure following DALK (relative risk 2.4, 95%CI 1.0-5.5, p=0.004). More patients achieved a BCVA of ≥6/6 following PKP (39%) than DALK (29%) (p=0.002).
Conclusions:
Graft survival following DALK is similar to that following PKP. Ocular surface disease is an important risk factor following DALK. We were not able to identify a surgical learning curve following DALK in terms of graft survival, visual acuity or refractive error for surgeons already experienced in undertaking PKP.
Keywords: 479 cornea: clinical science •
754 visual acuity •
420 anterior chamber