Comparison between manual trephination versus femtosecond laser-assisted deep anterior lamellar keratoplasty for keratoconus

Background/aims To compare the outcomes of femtosecond laser-assisted deep anterior lamellar keratoplasty (F-DALK) versus manual trephination DALK (M-DALK) in patients with keratoconus. Methods In this retrospective, comparative, clinical study, medical charts of 860 patients with keratoconus who underwent F-DALK (n=391) or M-DALK (n=469) with the Melles's technique, and had at least a 12-month follow-up record were reviewed. The main outcome measures comprised best spectacle-corrected visual acuity (BSCVA), manifest refraction and keratometric indices. The postsurgical measurements were recorded for all patients at 12 months (suture-in condition), and a subset of patients with complete data at 24 months (suture-out condition; 111 F-DALK and 282 M-DALK cases). Results Both procedures had comparable mean (+/- SD) logMAR BSCVA at 12 months (0.18 +/- 0.12 for M-DALK and 0.17 +/- 0.12 for F-DALK; p=0.224) and 24 months (0.11 +/- 0.10 vs 0.09 +/- 0.09, respectively; p=0.166) examinations. M-DALK was associated with a significant more residual myopia at 12 months (-3.85 +/- 3.27 vs -1.94 +/- 2.86 D; p<0.001), and a milder similar trend at 24 months follow-up (-2.94 +/- 2.72 vs -2.38 +/- 2.65 D, p=0.064). The mean keratometry (12 months: 46.15 +/- 1.88 vs 44.39 +/- 1.72, p<0.001; 24 months: 45.33 +/- 2.37 vs 44.14 +/- 1.68, p<0.001) and apical keratometry values (12 months: 50.92 +/- 5.00 vs 47.13 +/- 2.38, p<0.001; 24 months: 50.29 +/- 4.25 vs 48.12 +/- 3.81) were significantly greater for M-DALK than F-DALK, while the keratometric astigmatism was similar (12 months: 2.62 +/- 1.58 vs 2.53 +/- 1.33, p=0.364; 24 months: 3.21 +/- 1.83 vs 3.34 +/- 1.88, p=0.529). Conclusions F-DALK for advanced keratoconus performs as well as M-DALK in terms of BSCVA and keratometric astigmatism in both suture-in (12 months) and suture-out (24 months) conditions. It might have advantages over M-DALK for residual myopia and restoring corneal anatomy.