Abstract
Purpose: :
Deep anterior lamellar keratoplasty [DALK] permits the surgical treatment of a diseased corneal stroma with preservation of the healthy recipient corneal endothelium. However, it is not yet known whether this results in an improvement in transplant survival, or whether the visual outcomes are comparable to a full thickness penetrating keratoplasty [PK]. To determine and compare mid-term graft survival and visual outcomes we followed-up a group of PKs and DALKs.
Methods: :
A keratoconic cohort, comparable for age, sex and ethnicity underwent corneal transplantation. All surgery, twenty PKs and twenty DALKs, was performed by one surgeon [BAN]. The 6- and 12-months post-op outcomes have been reported elsewhere [Funnell CL, Ball J, Noble BA. Eye 2006; 20:527-532]. A retrospective chart review was conducted of the original cohort. Refraction and best-corrected visual acuities [BCVAs] were recorded at 2- and 4-years post-op. Between groups comparisons were analysed with independent t-tests.
Results: :
At two years there were data for seventeen PKs and eleven DALKs. The mean postoperative spherical equivalent was -3.09 +/- 3.53DS for the PKs and -3.08 +/- 2.14DS for the DALKs [P=0.99], the mean refractive cylinder was 4.06 +/- 2.73DC [PKs] and 2.28 +/- 0.95DC [DALKs],P=0.06. The mean BCVAs were 6/7.5 and 6/9.5 for the PKs and DALKs, respectively [P=0.09]. At four years there were data for fourteen PKs and eight DALKs. The mean postoperative spherical equivalent was -3.58 +/- 4.58DS for the PKs and -4.53 +/- 4.10DS for the DALKs [P=0.63], the mean refractive cylinder was 4.85 +/- 4.46DC [PKs] and 3.06 +/- 1.74DC [DALKs], P=0.30. The mean BCVAs were 6/5 and 6/9+ for the PKs and DALKs, respectively [P=0.07]. Two PKs failed and required re-grafting. None of the DALKs failed.
Conclusions: :
Although there were no statistically significant differences between the two groups there is a trend for better visual acuity with PK than DALK at both two and four years post-op. However, of note is that none of the DALK group required re-grafting but two [10%] of the PKs failed, necessitating repeat corneal transplantation. We propose that lamellar transplantation may offer an improved chance of graft survival but at the expense of slightly reduced BCVA compared with PK.
Keywords: cornea: clinical science • keratoconus • transplantation