Acta Chirurgica 36. (1997)
Contents
Acta Chirurgica Hungarica, 36 (1-4) pp. 248-250 (1997) INTRASTROMAL CORNEAL RING, A NEW REFRACTIVE SURGICAL TECHNIQUE TO DECREASE MYOPIA. EXPERIMENTAL AND CLINICAL RESULTS Z. Nagy, G. Krasznai*, L. Módis Jr.**, I. Sefcsik’**, I. Furka*** and Irén Mikó*** Departments of Ophthalmology, Pathology, Géza Hetényi Hospital of Jász-Nagykun-Szolnok County ' Department of Ophthalmology , Department of Experimental Surgery, University Medical School of Debrecen, Hungary From among the wide range of keratorefractive operations, the authors applied the intrastromal corneal ring (ICR) technique to treat myopia. The results of operations performed on dogs' eyes were evaluated using slit lamp investigations, cornea topography and histological investigations. In the possession of favourable results, this kind of operation was successfully performed on three patients suffering from expressed unilateral myopia, too. The desired optical results (10,0 dioptres) proved to be permanent 3-10 months after surgery and were demonstrated by the patients' visual acuity as well as cornea topographic examinations. The surroundings of the PMMA ring situated intrastromally and the substance of the cornea remained calm and clear, respectively. The authors think that the ICR technique can successfully be applied in the treatment of myopia similarly to refractive surgical interventions such as radiai keratotomy (RK) and excimer laser photorefractive keratectomy (PRK), which are widely used methods these days. Keywords: intrastromal corneal ring, refractive surgery in myopia, animal experimental and clinical results Introduction Surgical interventions aimed at changing the refractivity of the cornea are collectively described as keratorefractive surgical techniques. Depending on the surgical technique, the various methods can be classified as follows: keratotomy; keratectomy; thermocoagulation of the cornea; keratomileusis and epikeratophakia. Certain operations (e.g. kératotomies) only allow the decrease of the refractivity of the cornea, whereas other methods (e.g. keratomileusis, keratectomy and keratophakia) enable the surgeon to increase or decrease the refractivity of the cornea as desired. In animal experiments, keratophakia was applied to decrease the refractivity of the cornea, but, instead of using a concave lens, a PMMA ring was implanted intrastromally. Anglo-Saxon literature gave the method the name of intrastromal corneal ring (ICR). Experience about the intracorneal ring gained in animal experiments was exploited in our clinical practice. Materials and Methods Operations were performed under veterinary surveillance, on mongrel dogs of medium size, following narcosis induced by Ketamin-Xylasin. A mark concentric to the optic zone was made with a trephine (used in keratoplasty) with a diameter of 7.0 mm. The optic zone itself was marked with a trephine 3.0 mm in diameter. A concentric tunnel was prepared between the two marks, in the half-thickness of the cornea, using a special knife developed by us. The PMMA ring (Medikontur Kft.) was cut through at one site and slipped into the tunnel. After the centring of the ring, the operation was completed by the 0231-4614 /97/ $ 5.00 © 1997 Akadémiai Kiadó, Budapest