Week 1 - Case File - Emergency Medicine, Section - Head, Eyes, Ears, Nose, & Throat, Case Study - Acute Angle-Closure Glaucoma

Definitions

• ACUTE ANGLE-CLOSURE GLAUCOMA: A rapid increase in intraocular pressure due to outflow obstruction of aqueous humor. This is a medical emergency.

• CONJUNCTIVITIS: Inflammation of the conjunctiva, leading to an injected “red eye.”

• CONSENSUAL PHOTOPHOBIA: Pain when a light is directed to the unaffected eye, which is suggestive of an iritis (anterior uveitis).

• SLIT LAMP EXAMINATION: Uses a special device with a high intensity light source focused on a thin sheet in conjunction with a binocular microscope to view the anterior and posterior aspects of the eye.

Approach to Acute Angle-Closure Glaucoma

Epidemiology

Globally, the highest prevalence rates of acute angle-closure glaucoma (AACG) occur in Chinese and Inuit populations. African Americans have much higher rates of primary open-angle glaucoma (POAG) with resultant blindness, but they have lower rates of AACG. Persons between the ages of 55 and 65 years have the highest incidence of AACG; women are affected more than men (3:1). AACG is likely to occur in 33% to 50% of a patient’s first-degree relatives, so patients should inform their family members if they are diagnosed.

Risk Factors

Risk factors for narrow angle closure include older age, age-related lens thickening and enlargement, anterior lens shift, hyperopia (far-sightedness with a shortened eyeball), and a relatively shallow anterior chamber. There is a 75% risk of a similar attack in the fellow eye if left untreated. Also, medications that cause pupil dilation and pupillary block can trigger AACG, including anticholinergics, tricyclic antidepressants, adrenergic agonists, and topical mydriatics. Nonpupillary block leading to bilateral acute angle closure has been associated with sulfur-containing drugs such as topiramate, hydrochlorothiazide, furosemide, and even acetazolamide. AACG can occur with stress, fatigue, dim lighting, or sustained work at close range. Many over-the-counter sympathomimetics or anticholinergics can cause AACG.

Pathophysiology

The major mechanism of AACG or primary angle-closure glaucoma is pupillary block of the trabecular meshwork outflow pathway. Normally, aqueous humor is produced by the ciliary body in the posterior chamber and diffuses through the pupil into the anterior chamber where it is drained via the trabecular meshwork. A balance exists between aqueous humor production and outflow to maintain a normal intraocular pressure (IOP). However, some individuals are predisposed to angle closure secondary to anatomic (angle crowding) and environmental factors such as drugs. Many other forms of glaucoma have a far more insidious presentation but still lead to a significant loss of vision.

Clinical Presentation

It is important to recognize AACG quickly since a delay in the diagnosis and treatment may result in permanent loss of vision. Patients with AACG have elevated IOP, optic nerve changes, and progressive visual field loss that begins in the periphery. It is always important to examine the asymptomatic eye for anterior chamber depth (the angle is usually also narrow) and elevated pressure. Common signs and symptoms include mild to intense eye pain, blurry vision, nausea, vomiting, abdominal pain, diaphoresis, and frontal headache. The symptoms of headache, nausea, vomiting, or abdominal pain may lead providers to focus on neurologic or gastrointestinal etiologies; however, AACG must always be considered if primary symptoms of acute, painful red eye with vision loss are present. The hallmarks of the physical examination include:

• Fixed, dilated, mid-position pupil

• Diffuse conjunctival injection

• Corneal edema (clouding) (Figure 49-1)

• Shallow anterior chamber (Figure 49–2)

• Slit-lamp examination that may reveal mild cell and flare but no hyphema or hypopyon (blood or pus in the anterior chamber)

• IOP elevated up to 80 mm Hg (normal is 9-21 mm Hg)

Figure 49–1.

Acute angle-closure glaucoma. The pupil is mid-dilated and fixed, and the cornea is cloudy. (Reproduced, with permission, from Tintinalli JE, Kelen GD, Stapczynski JS, eds. Emergency Medicine. 6th ed. New York, NY: McGraw-Hill; 2004:1460.)

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Figure 49–2.

Glaucoma. A. A physiologic block normally occurs where the posterior surface of the iris touches the lens. B. When this block is increased, the iris, as a result, bows forward (iris bombé) and the angle is narrowed and pressure increases. C. As pressure increases, the angle becomes blocked. (Reproduced, with permission, from Knoop KJ, Stack LB, Storrow AB, Thurman R, eds. Acute angle-closure glaucoma. In: The Atlas of Emergency Medicine. 5th ed. New York, NY: McGraw-Hill; 2021.)

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Treatment

Overview

Initially, the management goal of AACG is to decrease IOP by decreasing aqueous production and increasing outflow. An ophthalmologist should be consulted in the ED. Treatment modalities to decrease IOP include aqueous suppressants, osmotic agents, and miotic agents. After the corneal edema subsides, the definitive treatment is a laser peripheral iridectomy performed by an ophthalmologist. In some resource-limited countries, the definitive treatment is lens removal.

Decreasing Aqueous Humor Production

First, IOP is lowered by decreasing aqueous humor production with agents such as topical beta-blockers (timolol 0.5%), an alpha-2-agonist (brimonidine 0.1%), and/or a carbonic anhydrase inhibitor (acetazolamide 500 mg orally or intravenously). Of note, patients with sulfa allergies may not tolerate acetazolamide.

Osmotic Agents

Osmotic agents, such as mannitol and glycerol, can be used instead of acetazolamide to dehydrate the vitreous humor; the result is decreased intraocular fluid volume and thus decreased IOP. Mannitol may induce hypotension in patients with poor cardiac function; glycerol should be avoided in diabetic patients.

Miotic Agents

Miotics such as pilocarpine 1% to 2% enhance trabecular outflow by constricting the pupil and disrupting the corneal-iris apposition. However, their use is controversial. Topical beta-blockers and acetazolamide should be administered prior to the administration of pilocarpine since the ischemic iris sphincter may be unresponsive to pilocarpine at extremely high intraocular pressures (greater than 50 mm Hg).

Other Pharmacologic Agents

Administration of prednisolone acetate 1% eye drops should be considered, especially if the AACG is bilateral. The patient should also receive analgesic and antiemetic medications.

Approach to Red Eye

Differential Diagnosis of Red Eye

In addition to AACG, vision-threatening and painful causes of a red eye include severe conjunctivitis, keratitis, corneal ulcer, anterior uveitis, endophthalmitis, orbital cellulitis, scleritis, and temporal arteritis (Table 49–1). Causes of acute vision loss are outlined in Table 49–2. Examination with the slit lamp and fluorescein staining are required for all patients with a red or painful eye.

DIFFERENTIAL DIAGNOSIS OF RED EYE

DIFFERENTIAL DIAGNOSIS OF ACUTE VISION LOSS

Conjunctivitis

Bacterial Conjunctivitis

Gonococcal conjunctivitis (the most serious form of bacterial conjunctivitis) usually presents with an intensely red eye and copious purulent discharge, and it carries an increased risk of corneal ulcer and perforation. In contrast, chlamydial conjunctivitis generally presents with a more chronic clinical course, and although the conjunctivae are very red, there is typically scant discharge. It is important to recognize this diagnosis since the incidence of sexually transmitted chlamydial conjunctivitis is increasing.

Viral Conjunctivitis

Most conjunctivitis is viral and is often caused by adenovirus species. Epidemic keratoconjunctivitis (EKC) can be especially severe and contagious. Patients have profound conjunctival redness and swelling (chemosis), watery discharge, and lymphadenopathy. Many coronavirus disease 2019 (COVID-19) patients also present with conjunctivitis.

Distinguishing Bacterial from Viral Conjunctivitis

Distinguishing between bacterial and viral conjunctivitis can be challenging. A recent literature review suggests that a bacterial etiology is more likely if the patient has a diffusely red conjunctiva that renders the tarsal (eyelid) vessels indistinguishable, a purulent discharge, and bilaterally matted eyelids in the morning (morning gluing). A bacterial etiology is less likely if the eye redness is not noticeable at 20 ft or if the eyelids are not matted in the morning (see Table 49–3 for features of bacterial vs viral conjunctivitis).

Treatment

Bacterial conjunctivitis is usually treated with topical broad-spectrum antibiotics (eg, erythromycin or trimethoprim-polymyxin B), whereas viral conjunctivitis is self-limited and typically resolves in 2 to 3 weeks.

PRESENTING FEATURES OF BACTERIAL AND VIRAL CONJUNCTIVITIS

Keratitis

Corneal inflammation, or keratitis, may be due to viral or bacterial infection, contact lenses, trauma, or ultraviolet (UV) light (eg, sunlight, welding, or UV lighting). Slit-lamp examination should be performed. The most important pathogens to identify are herpes simplex virus (HSV) and herpes zoster virus (HZV) because, if untreated, corneal ulceration and scarring may occur.

• HSV: The clinical diagnosis of HSV is made by identifying multiple arborizing dendritic epithelial ulcers with terminal bulbs. HSV almost always stains with fluorescein, with the classic dendritic pattern. HSV corneal infections can also present in a more diffuse disciform or ulcerative pattern.

• HZV: These dendrites taper at their ends and are typically associated with periorbital dermatomal vesicular eruptions or lesions at the tip of the nose (Hutchinson sign of nasociliary involvement).

Severe keratitis can progress to a corneal ulcer, which may be visible to the unaided eye as a white defect. Distinguishing an ulcer from a corneal abrasion is clinically significant and can be challenging. Ulcers can be distinguished from abrasions on slit-lamp examination by the hazy/cloudy stroma that lies beneath the ulcer in contrast to the clear stroma deep to most abrasions.

Anterior uveitis

Also known as iritis, anterior uveitis is associated with pain, blurred vision, photophobia (direct and consensual), circumcorneal redness, and anterior chamber cells and flare. A hypopyon (layer of white cells) may be visible along the inferior rim of the anterior chamber. The affected pupil is smaller, irregular, and minimally reactive. IOP can be elevated. Etiologies include:

• Idiopathic

• Infectious (eg, tuberculosis, syphilis, HSV/HZV, toxoplasmosis, cytomegalovirus [CMV]), Lyme disease)

• Autoimmune (eg, sarcoidosis, collagen vascular diseases, human leukocyte antigen [HLA] B27 associated)

• Medications (eg, sulfas)

• Posttraumatic

Uveitis due to HSV and HZV is common in patients with human immunodeficiency virus (HIV). Treatment is complicated and may or may not involve topical corticosteroids, which increase the risk of glaucoma, cataracts, or reactivation of herpes simplex infections. For this reason, consultation with an ophthalmologist is strongly recommended.

Endophthalmitis

Endophthalmitis is inflammation of the vitreous humor and can be endogenous, secondary to hematogenous spread from a distant site, or exogenous from inoculation after penetrating trauma. Traumatic endophthalmitis usually develops within 3 days of penetrating injury, retained foreign body, or ocular surgery. Hallmark features include decreased vision, eye pain, hypopyon, anterior chamber cells and flare, an absent red reflex, and a hazy vitreous. In addition, varying degrees of eyelid swelling, chemosis (conjunctival swelling), and severe conjunctival injection will be present. Causative organisms include Bacillus cereus, coagulase-negative Staphylococcus, Streptococcus, gram-negative rods, and fungi. Any patient presenting with a hypopyon requires an emergent ophthalmology consult. Orbital computed tomography (CT) or ultrasound B-scan microscopy (UBM) may help diagnose a foreign body. Systemic and intravitreal antibiotics will be necessary to preserve any remaining vision.

Orbital cellulitis

Orbital cellulitis is an infection deep to the orbital septum and is usually associated with blurred vision, diplopia, conjunctival injection, lid swelling, proptosis, fever, toxicity, and limited or painful ocular motility. An orbital CT (axial and coronal cuts) is diagnostic and will often reveal sinusitis (often ethmoid). Admission and parenteral antibiotics are indicated. Preseptal or periorbital cellulitis is a superficial infection and a far less serious entity, but it can be difficult to distinguish from orbital cellulitis. In general, these patients appear less toxic, have less pain, and can be treated with oral antibiotics.

Subconjunctival Hemorrhage

Subconjunctival hemorrhages are caused by blood collecting between the conjunctiva and sclera. Despite their appearance, they are painless and do not affect vision. These hemorrhages are often spontaneous or may be associated with minor trauma, including coughing and sneezing. If a patient with subconjunctival hemorrhage from blunt trauma complains of pain or vision changes, providers should continue evaluating for hyphema, globe rupture, or retrobulbar hemorrhage. Patients should be informed that the redness (bruise) might take weeks to completely resolve.

Hyphema

Blunt trauma to the eye may result in a hyphema (blood in the anterior chamber) and associated symptoms of painful, blurred vision. With a hyphema, blood may be visible to the unaided eye if it layers, or it may only be seen with the slit lamp in the anterior chamber (microhyphema) on maximum magnification. Complications include staining of the cornea by the red cells (producing a partially opaque cornea), elevated IOP secondary to red blood cells occluding the trabecular outflow tract, and rebleeding. Initial treatment consists of head elevation, an eye shield to prevent additional trauma, mydriatics to paralyze the ciliary body allowing the iris to rest, pain medication, antiemetics, and consultation. Retrobulbar hematoma must also be considered in the setting of blunt eye trauma. If hematoma is suspected, the IOP should be evaluated, an orbital CT obtained, and preparations made for lateral canthotomy if the pressure is significantly elevated.

Scleritis

In scleritis, the conjunctival, episcleral, and scleral vessels are inflamed, either diffusely or focally. Unlike episcleritis, which usually involves a milder pain, symptoms of scleritis include severe eye pain, redness, and decreased vision. It is also often associated with an underlying systemic disorder, such as a connective tissue disease, autoimmune disorder, HSV, HZV, HIV, Lyme disease, or syphilis. Rheumatoid arthritis is the most common systemic etiology, and HZV is the most common infectious cause. In contrast to episcleral vessels, scleral vessels do not blanch with topical vasoconstrictors or move under cotton swabs. Additionally, the entire sclera may have a bluish or violaceous hue and may be very tender upon palpation.

Treatment of scleritis involves treating the underlying disorder, which may involve systemic corticosteroids, immunosuppressive therapy, and nonsteroidal anti-inflammatory drugs (NSAIDs). This is always done after consultation with an ophthalmologist. Ultrasound may be useful in the assessment of posterior scleritis.