Eighty-one patients with a previous differential ocular response to topically administered steroids were evaluated for a change in plasma cortisol after being given 0.75 mg of orally administered dexamethasone. Twenty-four hours after administration, a differential response in plasma cortisol was noted. A statistically significant negative correlation was found between the previous change in ocular pressure and the present change in plasma cortisol. The correlation was significant for white patients but not for Negroes. Patients with a high ocular pressure response to topically administered steroids and a small decrease in plasma cortisol resemble patients with Cushing's Syndrome in their response to orally given dexamethasone. Unlike the topical steroid test, the dexamethasone suppression test does not depend on the patient's cooperation for a long-term treatment. The dose is accurately administered, and the response is objectively evaluated within a short period of time.
Levene RZ, Schwartz B. Depression of Plasma Cortisol and the Steroid Ocular Pressure Response. Arch Ophthalmol. 1968;80(4):461-466. doi:10.1001/archopht.1968.00980050463010