Immunohistochemical localisation of intravitreally injected bevacizumab in the anterior chamber angle, iris and ciliary body of the primate eye.

Aims: To locate bevacizumab in the tissues related to neovascularisation in the anterior segment within 1 14 days after intravitreal injection in the primate eye. Methods: Four cynomolgus monkeys received an intravitreal injection of 1.25 mg bevacizumab. Control eyes remained untreated. The eyes were enucleated on day 1, 4 and 14 for immunohistochemistry, using donkey anti-human Cy3-IgG. Results: Immunoreactivity for bevacizumab was found in the blood vessels walls of the iris, anterior chamber angle and ciliary body. In the iris and chamber angle, immunoreactivity was most prominent on day 1 after injection and diminished until day 14. In the ciliary body, staining was most intense on day 4 and remained prominent until day 14. Immunoreactivity was also present in certain vessel lumens, especially in the ciliary body and the iris on day 4 and 14. Conclusion: Bevacizumab penetrates quickly into the iris, anterior chamber angle and ciliary body after intravitreal injection in the primate eye and accumulates particularly in blood-vessel walls. The highest concentration of bevacizumab in these tissues is present on day 1 - 4, the iris and anterior chamber angle being penetrated slightly earlier than the ciliary body. Our findings support the clinically observed rapid effect in the treatment of iris neovascularisation.