Acute effects of dexamethasone on intraocular pressure in glaucoma

The effects of 3 mg orally administered dexamethasone on the intraocular pressure (IOP) were examined in four patients with primary open-angle glaucoma hospitalized for this study. Plasma-free glucocorticoid activity was measured by a radioreceptor assay. Diurnal rhythms of IOP and plasma-free glucocorticoid activity were detected prior to administration of dexamethasone. The plasma-free glucocorticoid activity rose two- to threefold in the 30-min period following steroid administration and then declined throughout the rest of the day. IOP was approximately 2 mmHg higher in the 0-4-hr period and approximately 5.5 mmHg higher in the 4-8-hr period following the pharmacologic doses of dexamethasone compared with similar periods on control days. The increase in the IOP was highly significant (P less than 0.006) in the latter time period. These findings suggest that the glucocorticoids may have a greater role in regulating IOP than generally has been appreciated.