Early Postoperative Results Of Flek (Femtosecond Laser-Enabled Keratoplasty) In A Retrospective Cohort Study In A Real-World Corneal Service.

To evaluate early post-operative results of FLEK (Deep anterior lamellar keratoplasty femto DALK, penetrating keratoplasty femto-PK) in a variety of corneal diseases in terms of safety, adverse events, and visual rehabilitation.

The Victus (Bauch & Lomb) femtosecond laser was used with software version 3.4.

Topographic data were collected with Anterion (Heidelberg Engineering), a swept source OCT. 

A femto-mushroom configuration was used to trephine donor and host of variable dimensions: External surface 8.3-9.0 mm and an internal surface 6.0-7.5 mm, depending on pre-existing pathology. Side cut (external) was cut at 120 degrees angulation and bottom side cut angle (internal) was cut at 90 degrees angulation.

This is a single-centre, retrospective cohort study of post-operative results of 2 surgeons (1 consultant and 1 fellow). 17 patients underwent FLEK, in a 24-month period. No cases were excluded from the series. A variety of corneal diseases were included: Keratoconus, Granular dystrophy, Acanthamoeba keratitis, Pseudomonas keratitis scarring, Herpes Simplex Virus Keratitis and trauma.

7 patients underwent femto-DALK and 10 patients underwent femto-PK. All cases (17) were performed with double continuous 10.0 nylon using a torque/anti-torque technique of 12 bites each. Adjustment of suture was performed in 7 of the patients in the clinic between 4-8 weeks post-operatively.

3-5 months results. Mean pre-operative VA was 0.88 LogMAR (Std Dev + 0.26, 0.2-1.1). Post-operative VA improved to 0.39 LogMAR (Std Dev + 0.22, –0.1- 0.7). The mean post-operative difference in topographic corneal astigmatism was 2.41D (Std Dev + 1.95,  0.33-7.1). The mean post-operative refractive sphere was –0.05D (Std Dev + 4.37D, -11D – +5.5D) and cylinder –1.39D (Std Dev + 0.75D, –0.5D - -3.25D). Postoperative average Kmax was 49.92D (Std Dev + 3.56D, 44.83D - 56.68D). 35.3% or patents obtained visual acuity of 6/12 or better. 94.1% of patients had 4D of topographic cyl or less with 52.9% having below 2D of cyl and 29.4% less than 1D cyl. No intraoperative complications, immunologic rejection episodes or graft failures were recorded.

FLEK is an advancement to conventional trephination. Wound integrity is stronger due to precise mushroom femtosecond laser trephination of donor and host tissue. This translates in faster healing and visual rehabilitation as demonstrated in this study with more than half (9) patients had topographic astigmatism <2.0D at 3-5 months follow-up. The mushroom configuration decreases the risk of endothelial rejection as a smaller internal diameter is used.