9.1 Acute Red Eye, Glaucoma & Uveitis

Evaluation of the Acute Red Eye

The presentation of an acute red eye is a common clinical scenario in primary care and emergency departments. Triage requires distinguishing benign, self-limiting conditions from sight-threatening emergencies. Key historical details include the presence of pain (dull ache vs. foreign body sensation), photophobia, visual changes, and type of discharge. Physical examination must assess visual acuity, pupillary size and reactivity, pattern of conjunctival injection, corneal clarity, and intraocular pressure.

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Conjunctivitis: Differentiating Viral, Bacterial, and Allergic Etiologies

Conjunctivitis is the most common cause of red eye, characterized by inflammation of the conjunctiva. Differentiating the etiology is critical to avoid unnecessary antibiotic prescriptions and limit transmission.

1. Bacterial Conjunctivitis

• Pathogens: Most commonly Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae.
• Clinical Presentation: Typically starts unilaterally but can spread to the contralateral eye. The hallmark is a copious, purulent or mucopurulent discharge that reaccumulates after wiping. Patients frequently report their eyelids are "stuck shut" in the morning.
• Hyperacute Bacterial Conjunctivitis: A critical variant caused by Neisseria gonorrhoeae. It features a rapid onset (within hours) of extremely profuse, thick purulent discharge, severe chemosis, and eyelid edema. This is a medical emergency due to the risk of rapid corneal perforation and requires systemic treatment with a single dose of intramuscular ceftriaxone (1g), along with saline lavage.
• Management: Routine bacterial conjunctivitis is self-limiting but topical antibiotics speed recovery. First-line choices include erythromycin 0.5% ophthalmic ointment or polymyxin B/trimethoprim drops. Fluoroquinolones (e.g., ofloxacin 0.3% or moxifloxacin 0.5%) are preferred in contact lens wearers to cover Pseudomonas aeruginosa.

2. Viral Conjunctivitis

• Pathogens: Most commonly adenovirus (highly contagious).
• Clinical Presentation: Often starts unilaterally and spreads to the other eye within 24–48 hours. Characterized by watery, serous discharge, follicular conjunctivitis (bumps on palpebral conjunctiva), and a tender preauricular lymph node. It is often associated with an upper respiratory tract infection (pharyngoconjunctival fever).
• Management: Supportive. Artificial tears, cold compresses, and strict hand hygiene to prevent transmission. Antiviral drops are not indicated unless herpes simplex virus (HSV) is suspected (which typically presents with unilateral dendritic corneal ulcers).

3. Allergic Conjunctivitis

• Pathogens: Environmental allergens triggering an IgE-mediated hypersensitivity reaction.
• Clinical Presentation: Almost always bilateral. The key diagnostic symptom is intense pruritus (itching). Discharge is typically watery or stringy and mucoid. Examination reveals chemosis, eyelid edema, and cobblestoning (large papillae) on the tarsal conjunctiva.
• Management: Avoidance of triggers. First-line pharmacotherapy includes topical dual-action mast cell stabilizers and antihistamines (e.g., olopatadine 0.1% or 0.2% or ketotifen 0.025%).

Acute Angle-Closure Glaucoma (AACG)

Acute angle-closure glaucoma is an ophthalmic emergency characterized by a rapid, severe rise in intraocular pressure (IOP) due to physical occlusion of the iridocorneal filtration angle.

• Risk Factors: Hyperopia (farsightedness, as these eyes have shorter axial lengths and shallower anterior chambers), female sex, older age, Asian ethnicity, and pupillary dilation (e.g., entering a dark theater, stress, or medications like sympathomimetics, anticholinergics, or TCAs).
• Clinical Presentation: Sudden onset of severe, boring unilateral eye pain, headache, nausea, vomiting, blurry vision, and halos around lights.
• Physical Exam Findings:
  • Ciliary flush (circumcorneal injection).
  • Steamy (cloudy) cornea due to corneal edema.
  • Mid-dilated, non-reactive (fixed) pupil.
  • The eyeball feels rock-hard to palpation.
• Diagnostic Tools:
  • Tonometry: Measures IOP. Normal IOP is 10–21 mmHg. In AACG, IOP is typically elevated to >50 mmHg. Gold-standard measurement is Goldmann applanation tonometry.
  • Gonioscopy: The gold standard for visualizing the iridocorneal angle directly, confirming closure.
• Emergency Management:
  1. Reduce Aqueous Humor Production: Administer intravenous acetazolamide (500mg) immediately, along with topical beta-blockers (timolol 0.5%) and alpha-2 agonists (apraclonidine 1%).
  2. Facilitate Outflow: Once IOP falls below 40 mmHg (relieving iris sphincter ischemia), administer topical pilocarpine 1% or 2% to induce miosis, pulling the peripheral iris away from the trabecular meshwork.
  3. Definitive Treatment: Laser peripheral iridotomy (LPI). This creates a hole in the iris to restore fluid flow. It must be performed bilaterally, as the contralateral eye has predisposed anatomy.

Anterior Uveitis (Iritis)

Anterior uveitis is inflammation of the anterior uveal tract, primarily involving the iris and ciliary body.

• Etiology: Approximately 50% of cases are idiopathic. The remaining are frequently associated with HLA-B27 seronegative spondyloarthropathies (ankylosing spondylitis, reactive arthritis, psoriatic arthritis, inflammatory bowel disease), sarcoidosis, juvenile idiopathic arthritis, or infectious causes (HSV, VZV, syphilis, tuberculosis).
• Clinical Presentation: Unilateral deep, aching eye pain, photophobia (both direct and consensual photophobia—pain in the affected eye when light is shone into the unaffected eye due to shared pupillary constriction pathways), and decreased visual acuity.
• Physical Exam Findings:
  • Ciliary flush (circumcorneal redness).
  • Constricted (miotic) pupil on the affected side due to sphincter muscle spasm.
  • Keratic precipitates (KPs): Inflammatory cell deposits on the posterior corneal endothelium.
  • Hypopyon: A visible layer of white blood cells settling in the inferior anterior chamber in severe cases.
  • Synechiae: Adhesions between the iris and the lens (posterior) or cornea (anterior), causing an irregular pupil.
• Slit-Lamp Examination: The diagnostic gold standard, showing cells and flare (proteins leaking from inflamed blood vessels) suspended in the aqueous humor of the anterior chamber, reminiscent of dust motes in a projector light beam.
• Management:
  1. Topical Corticosteroids: E.g., prednisolone acetate 1% drops to suppress intraocular inflammation.
  2. Topical Cycloplegics: E.g., cyclopentolate 1% or homatropine 5% drops. These dilate the pupil, keeping the iris away from the lens to prevent synechiae, and paralyze the ciliary muscle to relieve painful ciliary spasm.
  3. Referral: Immediate referral to ophthalmology. Steroids should never be initiated without confirming the absence of dendritic corneal ulcers (HSV) or corneal abrasions via fluorescein staining.