The water provocative test in preglaucomatous chickens.

Our ability to induce glaucoma in birds provides an experimental system for exploring the mechanisms involved in the provocative water test. Waters loads of a level comparable to those used clinically produced larger intraocular pressure (IOP) changes in preglaucomatous and glaucomatous birds than in control birds. The magnitude of the response corresponded to the level of IOP before testing, that is, to the severity of the glaucoma. Changes in systemic blood pressure were not involved in the response. While hyotonicity of plasma may be the systemic determinant, the normal range of variation in this factor does not allow us at present to consider this a causal relationship.