[The intrastromal corneal ring (KeraVision Ring, ICR, ICRS). A modern method for correcting minor myopia].

For the correction of low myopia several competing surgical methods have been developed over the last two decades: radial keratotomy (RK) and photorefractive keratectomy (PRK) are used clinically on a very large scale. Both techniques are basically irreversible. RK does structurally weaken the cornea and PRK has to be applied directly at the optical center. Both disadvantages can to a large extent be avoided by the recently introduced Intrastromal Corneal Ring (ICR) that is now implanted worldwide following a long experimental and clinical development phase. The device is manufactured from PMMA and is effective by volume addition in the corneal periphery, shortening of the central arc length and thereby flattening the central optical zone. The latest development uses two ICR-Segments (with an arc length of 150 degrees each) that are placed in the deep stromal layers via a small radial incision. The surgical details, refractive results and intra- and postoperative complications of both, several international studies (with up to 5 years of follow-up), and our own experiences (25 eyes, follow-up 9 months) are presented. The ICRS (KeraVision Ring) seems to offer a precise and stable method to correct low myopia. The procedure is reversible to a large extent, potentially adjustable within certain limits and carries a minimal risk only. A short comparison with RK and PRK is attempted. Although long-term follow-up is not available yet, initial results of the technique seem very promising.