The intrastromal corneal ring (ICR), a new keratorefractive device designed to correct myopia, was evaluated for safety and efficacy as part of a phase I Food and Drug Administration clinical trial.
Patients and Methods:
Ten patients, each with one nonfunctional eye, underwent surgical implantation of the ICR, which is a split ring composed of polymethyl methacrylate. The eyes were followed up during a 1-year period and were evaluated for wound healing, implant-related inflammation, intraocular pressure, corneal thickness, endothelial cell count, and refractive effects.
Wound healing was uncomplicated in all of the patients. No patient experienced implant-associated inflammation or extrusion. Intraocular pressure, corneal thickness, and endothelial cell counts were unaffected by the ICR. Non—sight-threatening intraoperative events included ring decentration and inadequate attachment of a vacuum-centering guide. The ICR reduced keratometrically determined spherical equivalence by an average of −2.5±1.1 diopters (mean±SD). Spherical equivalence, as determined by retinoscopy, was reduced by an average of−2.4±1.0 D. Results of corneoscopy and computerized videokeratography further confirmed this reduction of myopia.
The ICR may be a safe and efficacious device that offers predictable results with few side effects, and it may be a feasible alternative to current keratorefractive procedures.
Assil KK, Barrett AM, Fouraker BD, Schanzlin DJ. One-Year Results of the Intrastromal Corneal Ring in Nonfunctional Human Eyes. Arch Ophthalmol. 1995;113(2):159-167. doi:10.1001/archopht.1995.01100020041026