Inverse Cutting of Posterior Lamellar Corneal Grafts by a Femtosecond Laser

Jesper Hjortdal

doi:10.2174/1874364101206010019

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.

Highlights

Posterior lamellar keratoplasty, most often performed as Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK), has become the standard treatment for patients with symptomatic Fuchs’ endothelial dystrophy and secondary bullous keratopathy.The donor lamellar graft is prepared by removing most of the anterior corneal stroma by a mechanical microkeratome either in the eye bank or by the surgeon immediately before surgery
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

Summary

Introduction

Most often performed as Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK), has become the standard treatment for patients with symptomatic Fuchs’ endothelial dystrophy and secondary bullous keratopathy.The donor lamellar graft is prepared by removing most of the anterior corneal stroma by a mechanical microkeratome either in the eye bank or by the surgeon immediately before surgery. The resulting posterior lamellar grafts often vary considerably in thickness and are typically thicker at the periphery than in the centre. As graft thickness significantly may influence the final visual acuity in the recipient [1], it would be preferable to improve the cutting technique to ensure that the donor grafts are always prepared very thin. The negative optical power of microkeratome prepared grafts results in a small, but significant hyperopic shift in the refractive power of the recipient [2]. This could be avoided if the donor grafts were prepared to have even thinness

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