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In the past I5 years various types of scleral contact lenses have been developed for the treatment of pathological conditions of the cornea and conjunctiva. Our previous investigations found the hydrophilic corneo-scleral lens very effective in the treatment of various inflammatory and degenerative corneal changes (Krejci, I970, 1971).In our present study the Czech hydrophilic corneo-scleral contact lens (Spofa lens) has been employed in the treatment of dry eye caused by various conditions such as keratoconjunctivitis sicca, filamentous keratitis, keratitis pemphigoides, Stevens-Johnson syndrome, xerosis, and keratosis corneae, and also in the therapy of dry corneal spots caused by chemical burns. Material and methodsThe lens is composed of a hydrophilic polymer of hydroxyethyl methacrylate cross-linked with ethylene glycol dimethacrylate. The thickness of the lens varies between 0-3 and I *3 mm. and the overall diameter between I4-0 and i6-8 mm. The lens has a corneal and scleral curvature and the variable saggital depth permits correct fitting according to the irregularities and pathological changes in the cornea and conjunctiva. These lenses differ from the conventional scleral lens in concept and design. It is not necessary to manufacture a mould of the anterior segment of the eye and then to form the lens over the mould as with the "hard" methylmethacrylate contact lens.The first and most essential part of the fitting technique is the ophthalmic and medical evaluation. A keratometer reading should be taken, a careful slit-lamp examination performed, and the diameter of the cornea measured. In all cases it is necessary to evaluate the microbiological condition of the cul-de-sac and to ensure that there is adequate space to fit the lens. The passage through the lacrimal sac has to be examined and the interpalpebral fissure and total size of the eye must be measured. Neither the apical clearance method, nor the usual alignment method is used. The lens is fitted to allow a I 0 to I-5 mm. distance between the apex of the cornea and the posterior surface of the lens. The average "hard" scleral lens has a minimum corneal clearance. The cornea-to-lens clearance is manufactured at 0-2 to 0 3 mm., evolving into a o i-O 15 mm. clearance when the lens is fitted. The gel lens relies on a corneal clearance of ten times this amount and produces a large pool of precorneal fluid.The slit-lamp examination is repeated to check the movement and centering of the gel lens as well as the thickness of the precorneal film. Fluorescein must only be used for any corneal disturbances with the lens off, otherwise the dye will be absorbed by the gel. The adaptation period based on the lens-cornea relationship is shorter than that required for the hard contact lens. It is possible to wear the gel lens for 8 to I2 hours daily from the first day and for 24 hours during the first week.The patients were shown how to insert and remove the lens and were instructed to boil the lens every 24 to 36 hours for 15 minutes in physiological saline. A...

In spite of a standard lime burn technique, the injured rabbit eyes revealed a great variety of corneal damage with totally or partially denuded epithelium and stromal opacities of varying intensity. Irrigation of the eye with water removed more than half of the calcium from the cornea. A further significant decrease of the calcium level was achieved by the action of hydrophilic gel contact lens presoaked with a 1.85% ethylenediamine tetra acetate (EDTA) solution. The lime-burned cornea does not prevent intraocular penetration of EDTA from contact lens fitted on the injured eye. A delay of 1 or 2 h in application of EDTA contact lens after the lime burn and water irrigation of the eye seems to enhance permeation of the chelating agent into the cornea

Hydrophilic contact lenses made of poly(hydroxyethylmethacrylate) gel were saturated with 1-percent [¹⁴C]-glycyl-bacitracin or 0.1 -percent[¹⁴C]-glycyl-polymixinBand then applied to the eye of rabbits for 1, 3 and 5 h. The rabbits were afterwards killed, the eyes enucleated and radioactivity was measured in the contact lenses, the corneas and in an aliquot of aqueous. It was found that in the 1st hour bacitracin was freed from the contact lenses somewhat more rapidly than polymixin B, after 5 h, however, the content of both antibiotics in the contact lenses was approximately the same, about 40% of the original amount contained in the saturated lenses. Penetration of bacitracin into the cornea and aqueous was also higher than that of polymixin B, on an average six times as high in the 1st hour, four times as high after 3 h and twice as high after 5 h application of the contact lenses. The results show that these antibiotics are easily released from the hydrophilic gel, but that penetration into the eye depends upon the structure and size of the molecule.