Szemészet, 1975 (112. évfolyam, 1-3. szám)
1975 / 3. szám
ing intralamellar plate has a shape of a disc, 6—8 mm in size, which usually has 8 round holes, 1—2 mm in diameter, or in case of tantalum plate — 3 elongated holes situated parallelly to the plate edge. Some other models of keratoprostheses have been tested, such as keratoprostheses with supporting intralamellar plate of polygonal and star-shaped configuration; keratoprostheses the supporting portion of which consisted of corneal tissue lamellae dried over silicogel; and keratoprosteses with a screwing in optical cylinder. In one series of experiments, keratoprostheses were implanted into a healthy cornea, in the other—into leucomas. Results of implantation into leucomatous tissue proved to be better than that into healthy one. Histologically, it was established that in uneventful course at postoperative period incapsulation of the prosthesis into corneal tissues takes place, while in other cases intensive inflammatory reaction was accompanied by destruction of surrounding tissue, which eventually led to extrusion of the implant. Experimental studies have shown that keratoprostheses, the optical cylinder of which was manufactured of polymethylmetacrylate and the fixating plate of tantalum, are much better tolerated by the eye, which permitted us to use them in humans. We have mainly used penetrating keratoprostheses for patients to whom optical keratoplasty was contraindicated or in cases in which corneal transplantation proved to be ineffective. At first, we performed anterior-penetrating alloplasty, but soon we got convinced that its optical results are rather low and gradually fall, because deeper layers of the cornea opacified along the posterior face of the implant. It should be said that non-penetrating alloplasty may produce optical effect only when deeper layers of the cornea are transparent, i. e. when lamellar keratoplasty may be performed with a lesser risk for the patient. For keratoprosthesing in humans, we have used keratoprostheses of various types and various materials, but mainly these were those consisting of polymethylmetacrylate optica] cylinder and tantalum fixating portion the construction of which has been permanently improved. Best results were obtained with our last — “tracery model” of keratoprostheses which is manufactured at the laboratory of prosthesing at our Institute. This keratoprosthesis consists of an optical cylinder of polymethylmetacrylate, 2—3,5 mm in diameter and 4 mm in length, and a fixating plate of tantalum, of a lightened, “tracery” construction, 6—8 mm in diameter. The refractive power| of the optical cylinder and the fixating plate are calculated and selected individually for every patient. The model of keratoprosthesis described above has been used in 70 patients with severe complicated leucomas, predominantly of burn etiology (32 eyes). The majority of the patients were previously subjected to various kinds of keratoplasty and other operations, such as surgical repair of Symblepharon or ankyloblepharon, cataract extraction, anti-glaucomatous operations. Before operation, all patients were thoroughly examined on the state of optic eye media and visual analyser. Besides usual methods of eye examination (evaluation of visual acuity, visual field, bio microscopy in visible light), biomicroscopy in infra-red and ultra-violet rays, ultrasonic echography, light effect of x-rays and studying of their diagnostic value for examination of leucomatous eyes (Yakimenko, 1972; Panfilova, Legeza, 1966; Guzarskaya, 1974) made it possible to receive detailed information about the state of optic media and visual analyser of such eyes in most of the cases, which are necessary for selection of patients for keratoprosthesing and choice of rational approach and cannot be made with the help of common methods of examination. The initial state of the eyes operated on was grave and complicated. In 66 patients, visual acuity before operation measured only light perception, and in 144
