Diagnostics: Elevated Intraocular Pressure

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Acute elevation in intraocular pressure (IOP) is an uncommon but dangerous finding in the emergency department that requires rapid management. The most concerning complication of elevated IOP is blindness, caused by ischemia to the optic nerve (1). The diagnoses that most commonly present with increased IOP include open- and closed-angle glaucoma, chemical injury, and retrobulbar hematoma (1). While chemical injury and retrobulbar hematoma often require additional surgical management (such as irrigation and lateral canthotomy, respectively), acute angle-closure glaucoma (AACG) requires quick reduction in IOP with topical therapies to limit the damage to the optic nerve (2). Therefore, AACG is the example we will use here to help describe the emergent management of increased IOP. While there are multiple medications available to decrease IOP emergently, there is varying consensus on the adaptation of specific protocols to treat elevated IOP.

Defining the cause

Due to rapidly increasing IOP, the patient with AACG typically presents to the emergency department with a chief complaint of an acutely painful red eye. Risk factors include age greater than 55, hyperopia, being of Inuit or Asian descent and female sex. Other secondary causes of AACG include eye diseases such as cataracts, ectopic lens, diabetic retinopathy or ocular ischemia, tumors, and sulfa-containing drugs (1). The diagnostic criteria for AACG, stated by the American Academy of Ophthalmology, includes (1):

  • 2 or more of the following symptoms

    • Ocular or periocular pain

    • Nausea or vomiting

    • Intermittent blurry vision

    • Vision with halos

  • IOP > 21mmHg at presentation

  • 3 or more of the following examination signs

    • Conjunctival injection

    • Corneal epithelial edema

    • Mid-dilated unreactive pupil

    • Shallow anterior chamber

While the IOP definition for AACG tends to be anything greater than 21mmHg, most cases present with IOP > 40mmHg (1).

Topical and Systemic Treatments for Elevated IOP

There are several topical and systemic medications that can be used to decrease IOP, both emergently and chronically. These medications generally fall into two categories for mechanism of action: reducing aqueous humor production and increasing aqueous humor flow. The medication classes include topical alpha-agonists, beta-blockers, prostaglandins, and cholinergics, along with systemic carbonic anhydrase inhibitors and hyperosmotic agents (3). Examples of these medications can be seen in the tables below. Definitive management for AACG is surgical, and can be accomplished through iridotomy, trabeculectomy, or other surgical modalities deemed appropriate by ophthalmology (1).

Topical MedicationClassMechanismPeak Effect
Brimonidine / Apraclonidine Alpha-agonistReduces aqueous humor production1-4h
Timolol / Betaxolol Beta-blockerReduces aqueous humor production1-2h
Latanoprost / Travoprost / BimatoprostProstaglandinIncreases aqueous humor flow2h
PilocarpineCholinergicPupillary constriction / increased aqueous humor flow30 min - 1h
Systemic MedicationClassMechanismPeak Effect
AcetazolamideCarbonic anhydrase inhibitor Reduces aqueous humor production15 min IV, 2-4h orally
Mannitol / GlycerolHyperosmoticReduces aqueous humor production30 min - 3h

There is limited research available on the emergent medical management of elevated IOP. However, there are several studies on the chronic management of open-angle glaucoma that can be extrapolated for this purpose. To determine the efficacy of topical agent monotherapy in lowering IOP, a meta-analysis was conducted by Van der Walk et. al which included 27 randomized controlled trials and over 6900 patients. This study determined that timolol as well as latanoprost, bitamoprost, and travopost are the most efficacious medications in lowering IOP when compared with other medications including alpha-2 agonists, such as brimonidine (4).  To assess the efficacy of combination therapies,  a meta-analysis performed by Cheng et. al compared the available fixed combination therapies in 41 RCTs which included over 5200 patients. This study found that the combination of latanoprost/timolol and travoprost/timolol were the most efficacious in lowering IOP compared to other combinations and with monotherapy alone (5). In regards to systemic medications, Choong et. al performed a study in which escalating therapies were performed to reduce IOP in the emergency department. Three stages of treatment were performed with patients initially receiving acetazolamide and a topical beta blocker, followed successively by glycerol, and then mannitol if IOP was not reduced to 35mmHg or 25% less than the presenting pressure. This study determined that in 95% of patients, satisfactory reduction occurred with an initial combination of systemic acetazolamide and a topical beta blocker, followed by a hyperosmotic agent if indicated (6).  Acetazolamide should not be administered in patients with sickle cell disease or those with a prior sulfa allergy.

Take Away Points

  • IOP measurements above 21 mmHg in the setting of ocular complaints are an indication for emergent treatment and referral

  • Topical prostaglandins and beta-blockers are the most effective emergent therapies in the management of elevated intraocular pressure

  • Combination therapies of prostaglandins and beta-blockers can be utilized if monotherapy is not sufficient and has been shown to lower IOP more effectively

  • Systemic medications such as acetazolamide are useful adjuncts in controlling elevated IOP and can be easily administered in the emergency department via PO or IV routes

Post by Melanie Yates, MD

Dr. Yates is a PGY-1 in Emergency Medicine at the University of Cincinnati

Peer Review by Shan Modi, MD and Ryan LaFollette, MD

Dr. Modi is a PGY-4 at the University of Cincinnati pursuing a critical care fellowship and Dr. LaFollette is an Assistant Program Director at the University of Cincinnati

References

  1. Khondkaryan A, Francis BA. Angle-Closure Glaucoma. https://www.aao.org/munnerlyn-laser-surgery-center/angleclosure-glaucoma-19. Published December 18, 2013. Accessed July 21, 2020.

  2. Weizer JS. Angle-closure glaucoma. UpToDate. https://www.uptodate.com/contents/angle-closure-glaucoma?search=acute+angle+closure+glaucoma. Published April 17, 2020. Accessed July 21, 2020.

  3. Emergency KT: Red Eye. TamingtheSRU.com. https://static1.squarespace.com/static/53c1a2cce4b0e88e61f99b70/t/55e7316ee4b0585349429fae/1441214830938/CPQE+Red+Eye+GuidelineFinal.pdf. Published September 20, 2011. Accessed July 21, 2020.

  4. van der Valk R, Webers CAB, Schouten JSAG, Zeegers MP, Hendrikse F, Prins MH. Intraocular Pressure–Lowering Effects of All Commonly Used Glaucoma Drugs. Ophthalmology. 2005;112:1177-1185.

  5. Cheng J-W, Cheng S-W, Gao L-D, Lu G-C, Wei R-L. Intraocular Pressure-Lowering Effects of Commonly Used Fixed-Combination Drugs with Timolol: A Systematic Review and Meta-Analysis. PLoS ONE. 2012;7(9).

  6. Choong YF, Irfan S, Menage MJ. Acute angle closure glaucoma: An evaluation of a protocol for acute treatment. Eye. 1999;13(5):613-616.