Inverse Cutting of Posterior Lamellar Corneal Grafts by a Femtosecond Laser

Abstract

Purpose Posterior lamellar grafting of the cornea has become the preferred technique for treatment of corneal endothelial dysfunction. Posterior lamellar grafts are usually cut by a micro-keratome or a femto-second laser after the epithelial side of the donor cornea has been applanated. This approach often results in variable central graft thickness in different grafts and an increase in graft thickness towards the periphery in every graft. The purpose of this study was to evaluate if posterior lamellar grafts can be prepared from the endothelial side by a femto-second laser, resulting in reproducible, thin grafts of even thickness.Methods A CZM 500 kHz Visumax femto-second laser was used. Organ cultured donor grafts were mounted in an artifical anterior chamber with the endothelial side up and out. Posterior grafts of 7.8 mm diameter and 130 micron thickness were prepared by femto-second laser cutting. A standard DSAEK procedure was performed in 10 patients with Fuchs endothelial dystrophy. Patients were followed-up regularly and evaluated by measurement of complications, visual acuity, corneal thickness (Pentacam HR), and endothelial cell density.Results Femto-laser cutting of grafts and surgery was uncomplicated. Rebubbling was necessary in 5 of 10 cases (normally only in 1 of 20 cases). All grafts were attached and cleared up during the first few weeks. After six months, the average visual acuity was 0.30 (range: 0.16 to 0.50), corneal thickness was 0.58 mm (range 0.51 to 0.63), and endothelial cell density was 1.570 per sq. mm (range: 1.400 to 2.000 cells per sq. mm). The grafts were of uniform thickness, but substantial interface haze was present in most grafts.Conclusions Posterior lamellar corneal grafts can be prepared from the endothelial side using a femto-second laser. All grafts were clear after 6 months with satisfying endothelial cell counts. Poor visual acuity caused by interface scatter was observed in most patients. Femto-second laser cutting parameters needs to be optimised to enable smooth cutting in the posterior stroma.

Graft Rejection and Graft Failure After Penetrating Keratoplasty or Posterior Lamellar Keratoplasty for Fuchs Endothelial Dystrophy

“…Visually compromising interface haze seems to be a significant limitation for the use of femtosecond lasers in posterior lamellar donor preparation. 11,16 Two patients were regrafted after 1 and 3 years because of progressive fibrous contraction of the lamellar graft. It is speculated that an asymmetric peripheral thickness of the DSAEK graft may induce this type of progressive contraction.…”

“…In one case, a VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) was used to prepare the graft; for details, see Hjortdal et al 11 Posterior lamellar grafts were punched out to a diameter of 8.00 mm and either taco-folded and inserted with a forceps (first 17 eyes) or pulled into the anterior chamber using a Busin glide and forceps (last 85 eyes). At the end of surgery, the anterior chamber was filled with a large air bubble while the patient was left in a supine position.…”

Scanning Electronic Microscopy Evaluation of the Roughness of the Stromal Bed After Deep Corneal Cut with the LDV Femtosecond Laser (Z6) (Ziemer) and the ONE Microkeratome (Moria)

“…This result has important implications as it suggests that the LDV FS laser may produce a smoother graft-host interface, which has been associated with better visual outcomes. 17,19 With the LDV FS laser the attempted dissection depth was closer to achieved depth and more predictable than with the ONE Microkeratome. These results correspond with the results of Price et al who found that ONE Microkeratome with the 350 µm head the achieved dissection depth approximately 100 µm greater than intended.…”

Combined Use of a Femtosecond Laser and a Microkeratome in Obtaining Thin Grafts for Descemet Stripping Automated Endothelial Keratoplasty: An Eye Bank Study

“…Neff and colleagues (10) reported that grafts ≤131 µm provided a statistically significant improvement in best-corrected visual acuity compared with thicker grafts. Several attempts have been made to develop a technique to create very thin DSAEK grafts, without wasting donor tissue (18)(19)(20)(21). A FS laser, without a microkeratome, was previously used for this purpose.…”

“…However, the resulting surface was not as smooth as from a microkeratome and concentric folds would form due to compression or irregularity of the posterior stroma (22,23). In addition, interface scatter may later appear (21). The method we describe here, the double-pass technique, combines the sequential use of a FS laser and a microkeratome.…”