The effect of autonomic agents on the pupil and the intraocular pressure of eyes treated with dexamethasone.

In an attempt to determine the presence or absence of correlation between the intraocular pressure-increasing and pupil-dilating effects of corticosteroids, the effect of topically applied dexamethasone and various autonomic agents has been studied in 12 hospitalised, healthy, young adult volunteers. Dexamethasone caused an average increase of intraocular pressure of 8-8 mmHg and of pupillary diameter of 0-36 mmHg; there was no significant correlation between the change in pressure and the change in pupil size. Furthermore, there was no correlation between magnitude of rise of intraocular pressure and miotic effect of methacholine 2 5 %, or mydriatic effect of epinephrine 0 I%, or norepinephrine 0 1%. Dexamethasone-treated eyes showed a greater decrease in pupillary diameter in response to methacholine than their untreated mates (-1I14 and -0-68 mm respectively) and a slightly smaller increase in response to epinephrine than their controls (-0 18 and -0 53 respectively). Methacholine caused an increase in intraocular pressure of 2-8 mmHg in control eyes and 6-0 mmHg in dexamethasone-treated eyes. Increases of less significance were caused by epinephrine and norepinephrine. Subjects with the largest rise of intraocular pressure in response to dexamethasone also showed the greatest increase in intraocular pressure in response to the autonomic agents and to the water drinking test. Furthermore, they had lower coefficients of aqueous outflow than those having smaller responses. Methacholine 2-5 % produced miosis in