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KMID : 0351619690100020057
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Kyungpook Medical Journal
1969 Volume.10 No. 2 p.57 ~ p.68
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Effects of ^(90)Sr. Beta-irradiation on an Alloxan-induced Corneal Neovascularization
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Abstract
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It is the purpose of this paper to decide the effective simallest doses and intervals of the fractional irradiation of beta-ray generated from the ^(90)Sr., using adult rabbits as a means of experimental animals. It has been found by previous research that ^(90)Sr. beta irradiation is the most effective therapeutic measure to curtail the corneal neovascularization process which is the usual accompaniment of the keratitis. For the best result, fractional irradiation of the beta-ray to the corneal lesion is found to be the choice of irradiation treatment. To the test of the author´s knowledge, there has teen no report on the subject of effective doses and intervals of fractional irradiation for the corneal neovascularization in literature. Thirty adult rabbits were divided into 5 groups. In the animals, the left side corneas were used for the experiment and the right side for control. To the anterior chamber of the eye, 0.4 ml. of 2.0% alloxan solution was injected to provoke a neovascularization of the cornea. Beta-ray irradiation was given to the corneas of the rabbits when the neovascularization progressed to the extent of 1.0-3.0mm. A single dose each of the following amount of irradiation were given: 600, 1,200, 1,800, 2,400 and 3,000 rads to the lesions of the left corneas of group Ⅰ, Ⅱ, Ⅲ, Ⅳ and Ⅴ, res[ectovely.
Following results were obtained:
1. In group 1, the 600-rad-irradiation group, the corneal neovascularization was inhibited until the 4th post-irradiation day. After this period, the inhibitory effect of the irradiation in the study group appeared to subside, and thereafter, the same progression rate in both control and study groups were noted. The mean progression rate of alloxan-induced neovascularization in the rabbit cornea during the period up to the 4th post-irradiation day was 0.34mm. per day, whereas the control rate was 0.48mm. per day. It appears that an additional repeated or fractional irradiation may he given effectively on the 5th post-irradiation day.
2. In group Ⅱ, the 1,200 rad irradiation group, a satisfactory inhibitory effect of corneal neovascularization was discernible up until the 8th post-irradiation day. The mean progression rate of the corneal vascular intrusion during the above period was 0.21 mm. per day for the irradiated animals while the control was maintained at 0.45 mm. per day.
3. In group Ⅲ, the 1,800 rad irradiation group, the mean extent of the daily vasular progression was 0.21mm. per day until the 10th post-irradiation day, while the control was maintained at 0.45mm. per day.
4. In group Ⅳ, the 2,400 rad irradiation group, and group Ⅴ, the 3,000 rad irradiation group, the corneal neovascularization was considerably curtailed respectively. The mean vascular progression rates were 0.19 and 0.13 mm. per day, for the group Ⅳ and Ⅴ.
5. In those group which received larger doses of beta-ray irradiation, the healing rate of the alloxan-induced corneal lesion tended to be slower than in the control group.
6. It appears that the inhibitory effect of the beta-ray irradiation on the corneal neovascularization takes place on the second post-irradiation day.
In conclusion, this author has found that the initial optimal doses of beta-ray irradiation and the proper intervals between the initial and second fractional irradiation is 1,200 rads and 8 days.
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