Flattening of central corneal curvature with Intrastromal Corneal Rings of increasing thickness: An eye-bank eye study

Abstract

Ntrastromal channels in 38 eye-bank eyes. Each of 33 eyes received one ICR; the mean change in dioptric data was obtained for four meridians using an intraoperative photokeratoscope. Intrastromal corneal rings of increasing thickness resulted in corneal flattening of 3.8 ± 1.1, 4.9 ± 0.6, 5.2 ± 1.1, 5.3 ± 1.9, and 7.3 ± 1.6 diopters, respectively, for keratoscope mire 2. One of each size ICR was placed into one of five additional eye-bank eyes; the degree of flattening measured by laser holographic interferometry was 1.8, 2.9, 5.5, 4.7, and 10.1 diopters, respectively, for the central 6 mm corneal zone. These results indicate that the ICR provides a fairly linear flattening relationship over the range of thicknesses tested. Additionally, laser holographic interferometry wave unit maps of preoperative and postoperative corneas demonstrated that the ICR tends to preserve positive corneal asphericity if present preoperatively. 1Reprint requests to Terry E. Burris, M.D., Northwest Corneal Services, 6950 SW Hampton, Suite 150, Portland, Oregon 97223. Presented in part at the Symposium on Cataract, IOL and Refractive Surgery, San Diego, California, April 1992, and at the Association for Research in Vision and Ophthalmology Annual Meeting, Sarasota, Florida, May 1992. Supported by KeraVision, Inc., Santa Clara, California, and Northwest Corneal Services, Portland, Oregon. Technical assistance by Paula Ousley and the Lions Eye Bank of Oregon, Portland, Oregon. © Williams & Wilkins 1993. All Rights Reserved....