One-year results of the intrastromal corneal ring in nonfunctional human eyes. Intrastromal Corneal Ring Study Group
K. K. Assil, A. M. Barrett, B. D. Fouraker and D. J. Schanzlin
Anheuser-Busch Eye Institute, St Louis University, MO.
OBJECTIVE: 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. RESULTS: 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. CONCLUSIONS: 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 keratore-fractive
procedures.
