Cushing Disease Masquerading as Glaucoma

ABSTRACT Objective Glaucoma is a well-recognized side effect of corticosteroids. However, steroid-induced glaucoma typically refers to that caused by exogenous corticosteroid administration. Glaucoma secondary to endogenous overproduction of corticosteroids has only been reported in a few case reports. We aim to bring attention to glaucoma as a rare but important manifestation of endogenous hypercortisolism. Methods Patient history, physical exam, laboratory results, and imaging studies were reviewed. Results We report a case of glaucoma as the initial presentation of Cushing disease (CD). The patient was diagnosed with glaucoma 16 months prior to his endocrinology evaluation. At our initial encounter, the patient had a cushingoid appearance. Levels of 24-hour urinary cortisol and late-night salivary cortisol were elevated. Serum cortisol was not suppressed by 1 mg of dexamethasone overnight, but it was suppressed by 8 mg of dexamethasone. Adrenocorticotropic hormone was also elevated. All other pituitary hormone axes were unremarkable (thyroid-stimulating hormone, free thyroxine, follicle-stimulating hormone, luteinizing hormone, growth hormone, prolactin, and insulin-like growth factor). Pituitary magnetic resonance imaging suggested a small adenoma (2 to 3 mm); therefore, the patient underwent inferior petrosal sinus sampling. The results were consistent with CD. Transsphenoidal resection was performed and final pathology confirmed an adrenocorticotropic hormone-positive adenoma. Hypercortisolism and intraocular pressures improved after the surgery. Conclusion Glaucoma can lead to irreversible blindness if left untreated or uncontrolled. However, endogenous hypercortisolism-induced glaucoma can be reversed with treatment of the underlying CD. Thus, heightened awareness of extraocular manifestations of secondary causes of glaucoma such as endogenous hypercortisolism is necessary in order to promote prompt evaluation and treatment.