Drugs and Glaucoma
Corticosteroid-induced glaucoma is an OAG caused by prolonged use of topical, periocular, intravitreous, inhaled, or oral corticosteroids. It mimics POAG in its presentation and clinical course. Approximately one-third of the population without glaucoma demonstrates an IOP elevation between 6 and 15 mm Hg in response to corticosteroids, and only a small percentage (4%–6%) has a significant IOP elevation of more than 15 mm Hg. A high percentage (up to 95%) of patients with POAG experience an ocular hypertensive response to long-term topical corticosteroids. The type and potency of the agent, the means and frequency of its administration, and the susceptibility of the patient all affect the timing and extent of the IOP rise. Risk factors for corticosteroid-induced glaucoma include a history of POAG, a first-degree relative with POAG, very young age (<6 years) or older age, connective tissue disease, type 1 diabetes mellitus, and myopia. The elevated IOP is a result of increased resistance to aqueous outflow in the trabecular meshwork. See also BCSC Section 9, Uveitis and Ocular Inflammation, for further discussion of corticosteroids.
Corticosteroid-induced IOP elevation may develop within weeks, months, or years of the drug’s use; thus, regular monitoring of IOP is recommended in patients receiving these agents. In general, the risk of IOP elevation is correlated with the glucocorticoid potency of the drug and its ability to penetrate the ocular surface. For example, some corticosteroid preparations, such as fluorometholone, rimexolone, medrysone, or loteprednol, are less likely to raise IOP than are prednisolone, dexamethasone, or difluprednate (see Table 16-15 in BCSC Section 2, Fundamentals and Principles of Ophthalmology). However, even weaker corticosteroids or lower concentrations of stronger drugs can raise IOP in susceptible individuals. A corticosteroid-induced rise in IOP may cause glaucomatous optic nerve damage in some patients.
The cause of the elevation in IOP may be related to an underlying ocular disease, such as anterior uveitis, as opposed to corticosteroid use. After the corticosteroid is discontinued, the IOP usually decreases with a time course similar to or slightly longer than that of the onset of elevation. However, elevated IOP may persist in some cases.
IOP may also become elevated in patients who have excessive levels of endogenous corticosteroids (eg, Cushing syndrome). When the corticosteroid-producing tissue is excised, IOP generally returns to normal.
Periocular injection of a corticosteroid, particularly triamcinolone acetonide, may result in elevated IOP. Medical therapy may lower the IOP, but some patients require excision of the corticosteroid depot or glaucoma surgery.
Intravitreous corticosteroid injection may be associated with transient elevations in IOP in more than 50% of patients. Up to 25% of these patients may require topical medications to control IOP, and 1%–2% may require incisional glaucoma surgery. In contrast, intravitreous implants that release corticosteroid are frequently associated with elevated IOP, often requiring patients to undergo incisional glaucoma surgery for IOP control. Surgical treatment has a high success rate in lowering IOP in these patients; laser trabeculoplasty may also be of benefit.
Cycloplegic drugs can increase IOP in individuals with open angles. Routine dilation for ophthalmoscopy may increase IOP; those at greater risk include patients with POAG, pseudoexfoliation syndrome, or pigment dispersion syndrome, as well as those receiving miotic therapy.
Intravitreous injection of anti–vascular endothelial growth factor (anti-VEGF) agents is a common treatment for choroidal neovascularization and macular edema. Intravitreous injection may result in a transient rise in IOP. Over time, repeated injections may result in sustained IOP elevation. The etiology of the elevated IOP is unknown, but theories include increased inflammation and injury to or mechanical blockage of the trabecular meshwork.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.