Excimer laser-assisted anterior lamellar keratoplasty for keratoconus, corneal problems after laser in situ keratomileusis, and corneal stromal opacities

Abstract

To evaluate excimer laser-assisted anterior lamellar keratoplasty to augment thin corneas as in keratoconus (<350 microm) and corneal ectasia after laser in situ keratomileusis (LASIK) and to treat anterior stromal opacities. Ophthalmology Department, School of Medicine, Gazi University, Ankara, Turkey. Thirteen eyes (5 keratoconus, 3 macular dystrophies, 1 post-LASIK ectasia, 1 post-LASIK interstitial keratitis, 3 post-herpetic keratitis sequelae) of 13 patients were included in this prospective study. The treatment group was divided into corneal ectasia and stromal opacity groups. A donor stromal button approximately 350 microm thick received a 100 microm excimer laser ablation on the endothelium. The remaining cornea (epithelium, Bowman's membrane, and stroma) was punched with a 7.5 or 7.7 mm trephine. After transepithelial ablation of the host cornea to 200 mum thickness, the corneal button was sutured with interrupted 10-0 monofilament nylon. Sutures were removed between 3 months and 6 months postoperatively. Preoperative and postoperative simulated keratometric cylinders and corneal thickness values were compared using the Wilcoxon signed rank test. The postoperative spherical equivalent refraction and best spectacle-corrected visual acuity (BSCVA) between the groups were compared using the Mann-Whitney U test. The mean follow-up was 27.6 months +/- 8.3 (SD). All patients gained 2 lines or more of BSCVA, and no patient lost a line. The mean corneal thickness was 381.2 +/- 88.2 microm preoperatively, which significantly increased to 534.9 +/- 96.6 microm postoperatively (P < .05). The mean preoperative simulated keratometric cylinder was 7.44 +/- 7.18 diopters (D); postoperatively, it decreased to 2.61 +/- 1.73 D (P < .05). There was no significant difference in postoperative spherical equivalent refraction or BSCVA between the groups (P > .05). This technique presents a different modality for the treatment of keratoconus, post-LASIK corneal problems, and other corneal stromal opacities with anterior lamellar keratoplasty. Additional studies with more patients and longer follow-up will help determine the role of this technique as a substitute for penetrating keratoplasty in these patients.