Some observations on the water drinking test in glaucomatous and non-glaucomatous subjects

Transitory models of experimentally induced intraocular pressure changes in the rabbit. A reappraisal

The purpose of this study was to evaluate the relationship between inducer dosage, animal weight, and kinetics intraocular pressure (IOP) changes in three transitory-induced models for antiglaucoma drugs screening: oral water-loading, 5% glucose intravenous administration, and 20% NaCl infusion. For these models, a dose-dependent elevation of IOP was observed in three weight groups of rabbits (1, 2.2, and 3.8 kg). Dose-effect relationships were established, considering for each weight group two relevant parameters: maximal IOP changes and areas under or upper the kinetic curves of IOP changes. Among the three models studied, our results led us to consider water-loading as a weight-independent model, allowing us to compare results obtained by this model in New Zealand rabbits with different ages (40-150 days) or weights (0.9-3.8 kg).

Ocular hypertension and systemic responses to the water-drinking test

Osmolal, electrolyte, and other responses in peripheral blood were recorded after water loading of patients with ocular hypertension and chronic simple glaucoma, and with a small group of younger normal subjects. The osmolal responses of the ocular hypertensive group were significantly greater than for the glaucoma group, and further differences in plasma potassium concentration were also found. Drinking habits may exert a significant influence in ocular hypertension. The relative contributions to the diagnostic category of the variables recorded was evaluated by discriminant analysis, and the application of this retrospective approach to the assessment of new patients is discussed.

The effect of reduced blood osmolality on intraocular pressure

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