Influence of Low Power Laser Irradiation on the Neovascularization in the Model of Arthus Phenomenon Induced in the Rabbit Cornea: A Controlled Study

Abstract

This study investigates the effects of low-power laser irradiation on neovascularization in bradytrophic tissue using rabbit’s cornea as a model. Making use of the immune reaction known as the Arthus phenomenon, we injected all rabbits with complete Freund’s adjuvant containing inactivated mycobacterium twice to stimulate B-cell activity, then injected them two more times with incomplete Freund’s adjuvant containing human serum in order to stimulate T-cell activity. One week after the experiment initiation we applied 0.5 ml of human serum intracorneally to both eyes in all rabbits in order to pruduce a surplus of antibodies. Sickle-shaped turbidity was observed immediately. The rabbits were then divided into control (n=17) and test groups (n=10) and the test group received low-power laser treatment using the HeNe laser at 5 mW for 2 min daily. Treatment was applied to only one eye. Compared to the sham irradiated group, we observed significant changes in the laser-group including increased vascular sprouting, longer duration of neo-angiogenesis, and creation of longer vessels. Vascular sprouting took place 24 hours after first irradiation in the test group and started at day 3 in the sham-irradiated control group. Vascularization ceased on day 8 in the control animals: sham-irradiated animals’ corneas appeared avascular from day 12 onwards. In the test group, alternatively, the vessels were still detectable 14 days after laser irradiation. Average vessel lenght was 6 mm in irradiated animals but only 4 mm in the control animals.

Based on the results of this investigation the authors suggest that irradiation of an Arthus phenomenon induced in the rabbit’s cornea with low-power laser is able to influence neoangiogenesis positively.