Light-induced avian glaucoma as an animal model for human primary glaucoma

Glaucoma can be induced in domestic chicks at the will of the investigator, by the simple device of rearing the chicks under continuous light. This light-induced avian glaucoma (LIAG) is presented as an animal model system for human open-angle glaucoma. A number of morphological and physiological findings in LIAG are reviewed, and the LIAG system is compared with several other glaucoma model systems, in dogs, rabbits and monkeys. Intraocular pressure in LIAG has been demonstrated to be responsive to several anti-glaucoma drugs, and the system could be used for further drug testing. Thus it is suggested that LIAG may be especially useful in studies seeking to understand human glaucoma, and how to forestall it, or treat it. As well, a prolonged "pre-glaucoma" period is available to the investigator working with LIAG, during which a pathological course is already underway in the eye, but intraocular pressure has not yet gone up.