One-Step Intraoperative Optical Coherence Tomography Guided Tunnel, Mushroom Femtosecond Laser Big Bubble Deep Anterior Lamellar Keratoplasty

Abstract

The aim of our study is to investigate the feasibility and outcomes of using a femtosecond laser (FSL) platform (Ziemer LDV Z8) for deep anterior lamellar keratoplasty (DALK), enabling the creation of mushroom-shaped graft-host junctions, lamellar cuts, and intrastromal tunnels, to facilitate the big bubble, in one step. We included wet lab experiments on nine porcine eyes to assess the laser accuracy and cuts depth using an anterior segment (AS) OCT. This was followed by an interventional prospective case series on 10 eyes with variant corneal pathologies. The Z8 system, with in-built intraoperative optical coherence tomography (iOCT), guided corneal scans and directed the cuts. ASOCT showed visible mushroom configurations, lamellar cuts, and tunnels. Deviations from the target were 1.6%, 2.6%, and 3.5%. Anterior lamellar removal was easy in all clinical cases, including corneal scarring. The intrastromal tunnel was found at the preset location and the mushroom configuration was acquired. A big bubble was achieved in all cases. Type 1, 2, and 3 bubbles were formed in eight, one, and one case, respectively. We describe a new approach to DALK in which the in-built iOCT-guided FSL enables safe, precise, controlled, and reproducible desired cuts in one step. The preliminary clinical outcomes were favorable.

Keywords: deep anterior lamellar keratoplasty; femtosecond laser; intraoperative optical coherent tomography; intrastromal tunnel; mushroom configuration.

Figure 1

Mushroom configuration cuts with intrastromal tunnel of the host cornea of fresh porcine eye. (a) A diagram of the applanated cornea illustrating parameters. (b,c) iOCT photo from Z8 laser machine without “b” and with “c” illustrating parameters. (d) Immediately post-cut OCT obtained using Optovue (non-applanated surface) showing the corresponding cut.

Figure 2

Intraoperative photos of recipient preparation. (a) The mushroom cap and the offset part of the stem are removed as a single piece. (b) A Sinskey hook is used to easily find and open the tunnel in the residual stromal bed. (c) A canula is introduced into the tunnel. Notice the almost flat position of the cannula to avoid ripping the tunnel with the cannula shaft. (d) A type 1 BB was formed after air injection into the tunnel. (e) A bare DM following stromal removal. (f) The mushroom-shaped donor is placed.

Figure 3

Donor and recipient docking and laser cutting procedures. (a) The donor cornea is mounted onto the artificial anterior chamber. The laser handpiece is then docked to image and deliver programmed cutting. (b) iOCT photo from Z8 laser platform showing donor parameters adjustment. Full-thickness donor cutting occurs after determining the host matching stalk length. (c) Remaining corneoscleral rim showing full-thickness mushroom configuration cut. (d) Side view photo of the patient with MP showing short stature and difficult posturing. The patient’s head does not reach the edge of the surgical table. (e,f) Docking of the same patient. Notice the distance between the surgeon and the patient’s head and eye.

Figure 4

Corneal opacities encountered from several corneal pathologies. Preoperative photos and OCT: (a,f) LCD. (b,g) MP. (c,h) KC with apical scarring. (d,i) GCD1. (e,j) GCD2. Early postoperative photos and OCT of the same cases: (k,p) LCD. (l,q) MP. (m,r) KC with apical scarring. (n,s) GCD1. (o,t) GCD2.