Purpose:
To compare astigmatism in keratoconus patients who underwent deep anterior lamellar keratoplasty (DALK) to those who had penetrating keratoplasty (PKP), both performed with a femtosecond laser zig-zag incision.
Methods:
Retrospective study at a single center referral academic practice with 2-year followup. Candidates for DALK were selected. All cases were performed using the femtosecond laser zigzag pattern and all wounds were closed with an identical, 24-bite running nylon suture technique. Evaluated outcome measures included manifest refractive astigmatism, topographic astigmatism, best spectacle-corrected visual acuity (BSCVA), and recovery of full visual potential.
Results:
Manifest refractive astigmatism in DALK patients remained ≤ 3.88 diopters (SE +/- 0.962) throughout 2-year followup, with post-op month 1 predictive (2.83 D, SE +/- 1.04) of outcome. In comparison, manifest refractive astigmatism in PKP patients remained ≤ 3.62 diopters throughout the same 2-year interval, with post-op month 3 predictive (3.02 D, SE +/- 0.481) of outcome. For topographic astigmatism in those who had DALK, mean simulated keratometry measurement was lowest at 6 months post-operatively (3.17 D, SE +/- 0.726). In comparison, for topographic astigmatism in PKP patients, mean simulated keratometry measurement seemed to plateau starting at 3 months post-operatively (3.02 D, SE +/- 0.481). There was statistically no difference between DALK and PKP in terms of manifest refractive astigmatism (P = 0.8159) and topographic astigmatism (P = 0.8042) in our patient population.
Conclusions:
Using the femtosecond laser to generate a zig-zag-shaped incision for corneal transplantation yields consistent results, rapid recovery, low astigmatism, and promising postoperative visual outcome. Based on our study, keratoconus patients who underwent DALK with femtosecond laser zig-zag incision had no statistical difference in astigmatism compared to those who had PKP with the same instrument. Further studies are warranted for definitive conclusions.
Keywords: transplantation • astigmatism