A randomized controlled trial comparing femtosecond-enabled deep anterior lamellar keratoplasty and standard deep anterior lamellar keratoplasty (FEDS Study)

Objectives: To compare outcomes of femtosecond-enabled deep anterior lamellar keratoplasty (FE-DALK) and standard deep anterior lamellar keratoplasty (S-DALK). Methods: An open label, randomized controlled trial (Kensington Eye Institute, Toronto, ON, Canada) including 100 eyes of 97 participants with either keratoconus or corneal scarring, randomized to either FE-DALK (n = 48) or S-DALK (n = 49). Primary outcomes: postoperative astigmatism and surgically induced corneal astigmatism (SIA) – both at 15 months. Secondary outcomes: 6-, 12- and 15-month postoperative uncorrected- and best spectacle-corrected visual acuity, steep and flat keratometry, manifest sphere and astigmatism, rate of conversion to penetrating keratoplasty (PK), big-bubble success, central corneal thickness, endothelial cell count and complications. Results: In intention-to-treat analysis, mean postoperative astigmatism in the FE-DALK (n = 30) and S-DALK (n = 30) groups at 15 months was 7.8 ± 4.4 D and 6.3 ± 5.0 D, respectively (p = 0.282) with an adjusted mean difference of 1.3 D (95% CI −1.08, +3.65). Mean SIA (arithmetic) was 9.2 ± 7.8 and 8.8 ± 5.4 D, respectively (p = 0.838) with a mean difference of 0.4 D (95% CI −3.13, +3.85). In an analysis of successful DALK cases only, mean postoperative astigmatism in the FE-DALK (n = 24) and S-DALK (n = 20) groups at 15 months (after excluding 4 eyes with AEs) was 7.3 ± 4.4 and 6.2 ± 4.9 D, respectively (p = 0.531) with an adjusted mean difference of 0.9 D (95% CI −1.94, +3.71). Mean SIA (arithmetic) was 9.1 ± 7.8 and 7.9 ± 4.6 D, respectively (p = 0.547) with a mean difference of 1.2 D (95% CI −2.70,+5.02). Comparison of secondary outcomes showed only weak statistical evidence. Conclusions: In this randomized controlled trial, FE-DALK and S-DALK showed comparable functional and anatomical outcomes.