To compare the outcomes of femtosecond laser-assisted minimally invasive lamellar keratoplasty (FL-MILK) for mild-to-moderate keratoconus (KC) and advanced KC. Prospective case series study. Sixty-three eyes of 56 patients with progressive KC underwent FL-MILK were divided into group 1 [mean keratometry (Kmean) ≤ 53D] and group 2 (Kmean > 53D). Best spectacle-corrected visual acuity (BSCVA), Kmean, maximum keratometry (Kmax), anterior central corneal elevation (ACE), stiffness parameter A1 (SP-A1) and deformation amplitude (DA) were evaluated preoperatively and up to 24months postoperatively. Mean BSCVA improved from 0.34 ± 0.13 logMAR preoperatively to 0.25 ± 0.13 logMAR at 24months postoperatively in group 1 (F = 10.10, P < .0001), and from 0.54 ± 0.31 logMAR to 0.40 ± 0.26 logMAR (F = 9.06, P = .0002) in group 2. Group 2 showed an average Kmax reduction of 10.9 D and an average Kmean reduction of 3.9 D at 24months postoperatively (both P < .0001), whereas no significant change was observed in group 1. Average ACE decreased from 19.2 ± 10.0 to 5.2 ± 8.4 at 24months postoperatively in group 1 (F = 28.5, P < .0001), and from 46.2 ± 16.3 to 19.1 ± 9.0 (F = 49.6, P < .0001) in group 2; SP-A1 increased from 53.8 ± 12.7mmHg/mm to 95.9 ± 20.2mmHg/mm in group 1 (F = 70.0, P < .0001), and from 38.6 ± 13.4mmHg/mm to 89.3 ± 18.2mmHg/mm (F = 96.9, P < .0001) in group 2; DA decreased from 1.30 ± 0.14mm to 1.17 ± 0.13mm in group 1 (F = 14.0, P < .0001), and from 1.40 ± 0.16mm to 1.18 ± 0.10mm (F = 27.6, P < .0001) in group 2. FL-MILK can stabilize progressive KC in mild-to-moderate cases and advanced cases at 24-month follow-up. Steeper corneas are more likely to undergo flattening after FL-MILK. Date of registration: July 16, 2017. The title of the trail: www. gov Trial registration number: NCT03229239. The name of the trial registry: ClinicalTrials.gov.
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