Many investigations have been performed to evaluate the therapeutic usefulness of hydrophilic soft-contact lenses for the corneal diseases. In this study the author undertook to determine the uptake and release characteristics of soft contact lenses for the collagenase inhibitors and to investigate the clinical effectiveness far the alkali burfls of the cornea in -rabbits eyes.
A. Using Mycon-soft lenses (made by Tokyo contact lens Co., Japan), with different diame-ters (12.0mm, 14.5mm) and thicknesses (0. imm, 0.2mm), uptake and release in vitro and in. vivo of 0.2M cysteine and 0.2M EDTA solution were measured.
The results were as follows:
1. The amount of cysteine and EDTA taken up by soft contact lens was related to thetotal mass of soft contact lens.
2. The larger the soft contact lens, the longer was the time -required for uptake and release of cysteine and EDTA in vitro and in vivo.
In vitro, the cysteine uptake of a soft contact lens (diameter; 14.5mm. thickness; 0. 2mm) was complete in 60 minutes and the release was in 90 minutes. The EDTA uptake of a. soft contact lens (diameter; 14. 5mm, thickness;0.2mm) was complete in 10 minutes and the release was in 120 minutes.
In rabbit eye the cysteine release from a soft contact lens (diameter; 14. 5mm, thickness; 0. 2mm) was complete in 120 minutes of wear and the EDTA release was in 60 minutes. 3. Being the rate of release of cysteine and EDTA solutions slower in vivo than in vitro, drug effect of longer duration may be achieved by wearing soft contact lens presoaked in the solutions.
B. Alkali burns were induced on to enty rabbit corneas for thirty seconds with a soft contact lens (diameter; 14.5mm, thickness; 0.2mm, base curve; 7.00mm.), presoaked for five minutes in 0.5N sodium hydroxide solution. Healing rates of the corneal epitheliel defects of each group, treated with three drops of 1%, chloramphenicol solution and collagenase inhibitor, 0.03M EDTA solution, six times per day and with or without soft contact lens, sterilized and presoaked in solutions once a day, were measured with scaled celluloid plate and magnifier, after fluorescein staining of cornea for forty days and were compared each other.
The following results were obtained:
1. In animals treated with 1% chloramphenicol solution, soft contact lens has no influence on healing rate of corneal epithelial defect.
2. In animals instilled only with collagenase inhibitor, 0.03M EDTA solution, without soft contact lens, EDTA solution was not more effective than 1 % chloramphenicol solution.
3. On healing rate of corneal epithelial defect, 0. 03M EDTA solution was more effective in animals with soft contact lens than without soft contact lens.
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