[Keratomileusis in situ in high grade myopia. Initial results].

Besides photorefractive keratectomy (PRK) with the excimer laser, different methods of intrastromal keratectomy are now available for refractive corneal surgery in myopic patients. The first results of keratomileusis in situ in high-grade myopia are presented. Keratomileusis in situ was performed with a semiautomatic mechanical microkeratome in 15 amblyopic eyes with a refraction (spherical equivalent) between -12 and -25 D (mean -18.18 D). The principle of the method consists in a change of the anterior corneal curvature by resection of a refractive lenticulus out of the corneal stroma. The first step is the removal of a superficial corneal lamella consisting of epithelium, Bowman's layer, and superficial stroma. After this, the refractive lenticulus is resected out of the stroma, and the superficial lamella is sutured back to the cornea. The postoperative refraction (spherical equivalent) 4 weeks after the operation ranged between + 1.5 and -4.5 D (mean -1.37 D). Best corrected preoperative visual acuity was achieved again postoperatively within 4 weeks in most of the patients; in some patients the postoperative visual acuity even exceeded the preoperative values. After an uncomplicated healing process in 14 of the 15 eyes the cornea remained completely transparent in the optical zone, and the effect of treatment remained stable. Scar formation was observed in one eye only, where the lamellar cut was inadvertently performed in Bowman's layer and not in the stroma. Thus, keratomileusis in situ is a supplementary technique to conventional refractive surgery in high-grade myopia. Its advantages are quick optical rehabilitation and an almost scar-free optical zone, because the integrity of Bowman's layer is almost completely maintained with this technique.