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Original author: Terry Buzzard
Originally published in 2014. Substantially updated and clinically reviewed in 2026 to reflect current evidence, guidelines, and urgent care practice.
Introduction
The acute red eye is one of the most common problems presenting to urgent care centers. Because the redness may involve any one or more of the many structures that make up the eye, and because of the many possible causes of eye redness, the list of diagnoses can be fairly extensive, and the diagnosis challenging. Although most “red eye” problems are relatively benign, it is essential that the urgent care provider be able to recognize those conditions necessitating more immediate treatment or referral. A knowledge of certain key elements of the history and physical examination will enable the urgent care provider to promptly recognize and appropriately manage these conditions.
The central task remains distinguishing uncomplicated surface disease from corneal, anterior chamber, scleral, orbital, or intraocular disease that can threaten vision. Severe pain, photophobia, decreased vision, an abnormal cornea, an abnormal pupil, proptosis, pain with extraocular movement, or recent ocular surgery should immediately raise concern for a more serious process.
Presentation
Patients typically present with recent onset of varying degrees of redness of one or both eyes. They may know the cause of their problem or may have no idea what caused the redness. They also present with a range of symptoms, including pain, drainage, swelling, itching, photophobia, and vision changes, but they may also be completely asymptomatic.
Triage Pearls
- One of the first questions is whether there was an injury; if known or suspected, triage according to the acute eye trauma pathway.
- Evaluate immediately when severe pain, photophobia, decreased visual acuity, contact-lens-related painful red eye, copious purulent discharge, recent ocular surgery/procedure, facial vesicles, proptosis, painful/restricted extraocular movements, or suspected acute angle closure is present.
- Begin irrigation immediately for chemical exposure.
- Same-day ophthalmic evaluation is generally appropriate for reduced vision, corneal opacity/ulcer/dendrite, hypopyon, irregular pupil, or a relative afferent pupillary defect.
History Pearls
- Onset and context; exposure to others with similar symptoms; unilateral versus bilateral involvement.
- Pain, vision change, foreign-body sensation, itching, photophobia, and character of discharge.
- Contact lens use, including overnight wear and hygiene.
- Prior ocular disease or surgery, recent injection/procedure, and topical medications.
- Occupational/environmental exposure and systemic disease including immune compromise, atopy, autoimmune disease, and STI risk when relevant.
- A contact lens wearer with pain, photophobia, reduced vision, or a corneal abnormality should be presumed to have possible microbial keratitis until proven otherwise.
Physical Exam Pearls
- Document visual acuity in every patient.
- Document extraocular movement and pain with movement.
- Inspect face, lids, lashes, orbit, and skin.
- Evert the upper lid when a subtarsal foreign body is possible.
- Evaluate the cornea with fluorescein under magnification when appropriate.
- Assess the anterior chamber, pupils, and RAPD when indicated.
- Measure IOP when indicated and when open globe injury is not suspected; do not use globe palpation as a substitute for tonometry.
Diagnosis and Treatment Pearls
The conditions below are organized anatomically.
Figure 1. Nontraumatic Causes of Red Eye — 2026
| EYELIDS Blepharitis Hordeolum Chalazion Trichiasis Dacryocystitis Preseptal cellulitis | CONJUNCTIVA Viral/bacterial conjunctivitis Gonococcal/chlamydial conjunctivitis Allergic conjunctivitis Dry eye Subconjunctival hemorrhage Pterygium/pingueculitis | CORNEA Microbial keratitis HSV/VZV keratitis Superficial punctate keratitis Exposure keratopathy |
| ANTERIOR CHAMBER Anterior uveitis (iritis) Acute angle-closure crisis Hypopyon/hyphema | SCLERA Episcleritis Scleritis | ORBIT / INTRAOCULAR Orbital cellulitis Thyroid eye disease Endophthalmitis Other postoperative/intraocular inflammation |
Eyelids
Blepharitis
Blepharitis is a chronic recurrent inflammation of the eyelid margins. Initial treatment is warm compresses and regular eyelid hygiene. Topical antibiotics may be useful for selected anterior blepharitis, but prolonged antibiotic ointment is not necessary for every patient. Significant meibomian gland dysfunction or rosacea may require ophthalmic-directed therapy.
Trichiasis
Misdirected lashes cause foreign-body sensation, tearing, and redness. Look for fluorescein-staining corneal injury. Temporary epilation may help, but recurrent disease requires definitive ophthalmic treatment.
Hordeolum (Sty) and Chalazion
Warm compresses are first-line. Routine antibiotics are not indicated without blepharoconjunctivitis or cellulitis. Do not perform blind needle drainage. Refer persistent, recurrent, atypical, or vision-threatening lesions.
Dacryocystitis
Medial canthal erythema, swelling, tenderness, tearing, and discharge suggest dacryocystitis. Use systemic antibiotics and arrange ophthalmology follow-up; send toxic, febrile, rapidly progressive, or orbitally involved patients for emergency care.
Pediculosis of the Eyelashes
Mechanical removal and an ophthalmically safe occlusive agent may be used. Do not use pediculicide shampoo on the lashes or ocular surface. Older lindane-based regimens are no longer preferred.
Dry Eye Disease
Use preservative-free artificial tears and lubricating ointment as needed. Review medicines, contact lenses, environment, eyelid disease, and systemic symptoms. Persistent or moderate-to-severe disease requires longitudinal eye care.
Conjunctiva
Viral Conjunctivitis
Treat supportively with cool compresses, preservative-free tears, and hygiene. Antibiotics do not help viral disease. Avoid indiscriminate topical steroids. Photophobia, decreased vision, corneal findings, severe pain, or prolonged worsening requires ophthalmic evaluation.
Bacterial Conjunctivitis
Mild simple disease is often self-limited. A broad-spectrum topical antibiotic may be used when bacterial disease is likely, but no agent has proven clearly superior. Contact lens wearers with pain, photophobia, reduced vision, or corneal findings require same-day evaluation for microbial keratitis.
Gonococcal Conjunctivitis
Hyperacute copious purulent discharge with chemosis is a vision-threatening emergency. Treat adults with ceftriaxone 1 g IM once, consider saline lavage, treat chlamydia if not excluded, obtain STI testing, and arrange urgent ophthalmology/ED care.
Chlamydial Conjunctivitis
Systemic treatment is required. Doxycycline 100 mg twice daily for 7 days is preferred for most nonpregnant adults; azithromycin 1 g once is an alternative. Treat partners and follow current STI guidance.
Allergic Conjunctivitis and GPC
Use allergen avoidance, cool compresses, artificial tears, and topical antihistamine/mast-cell stabilizer therapy. Avoid chronic vasoconstrictor drops. Ocular steroids should generally be prescribed by eye care. Remove mechanical triggers in GPC.
Thyroid Eye Disease
Lid retraction, proptosis, chemosis, exposure keratopathy, diplopia, or conjunctival injection may occur. Reduced vision/color vision, RAPD, significant exposure, or new restrictive diplopia warrants urgent evaluation.
Pterygium and Pingueculitis
Lubricants and environmental protection are sufficient for many patients. Refer pterygia threatening the visual axis, inducing significant astigmatism, recurring with inflammation, or interfering with contact lens use.
Subconjunctival Hemorrhage
Usually painless with normal vision. Reassure that it clears over 1-3 weeks, check blood pressure, and review anticoagulants without stopping indicated therapy. Recurrent or traumatic cases require further evaluation.
Cornea
Microbial Keratitis (Corneal Ulcer)
A painful red eye with photophobia, reduced vision, and a corneal infiltrate/defect is microbial keratitis until proven otherwise. Stop contact lenses, do not patch or use topical steroids, and obtain same-day ophthalmic evaluation.
Herpes Simplex Keratitis
Dendritic fluorescein staining and reduced corneal sensation suggest HSV. Antiviral treatment is indicated; arrange same-day eye care. Do not use topical corticosteroids for epithelial HSV unless directed by ophthalmology.
Herpes Zoster Ophthalmicus
Start systemic antiviral therapy promptly—ideally within 72 hours, but later when new lesions or ocular involvement persists. Hutchinson sign increases risk but its absence does not exclude eye disease. Ocular symptoms/findings require ophthalmology.
Superficial Punctate Keratitis
This is a staining pattern with multiple causes. Treat the underlying cause and stop contact lenses. Refer moderate/severe pain, photophobia, reduced vision, focal infiltrate, or significant contact-lens-associated disease.
Anterior Chamber
Acute Anterior Uveitis (Iritis)
Aching pain, consensual photophobia, ciliary flush, blurred vision, and cells/flare suggest anterior uveitis. Arrange same-day ophthalmic evaluation. Topical steroid/cycloplegic therapy should generally be coordinated with ophthalmology.
Acute Angle-Closure Crisis
Severe pain, headache, nausea/vomiting, halos, corneal edema, a shallow chamber, mid-dilated pupil, and markedly elevated IOP suggest acute angle closure. This is an emergency requiring immediate transfer and definitive ophthalmic treatment.
Sclera
Episcleritis
Usually mild and self-limited, with normal vision. Artificial tears and cool compresses are often adequate; refer severe, recurrent, nodular, painful, visually symptomatic, or atypical disease.
Scleritis
Deep severe boring pain and deep nonblanching injection suggest scleritis. Urgent ophthalmology is required; systemic steroids/immunosuppression are specialist-directed after infectious causes are considered.
Orbital and Periorbital Tissues
Orbital Cellulitis
Proptosis, pain with eye movement, ophthalmoplegia, reduced vision/color vision, chemosis, RAPD, or toxic appearance suggests orbital disease. Send for emergency hospital care, orbital imaging, IV antibiotics, and ophthalmology/ENT management.
Preseptal Cellulitis
Vision, pupils, color vision, and eye movements should be normal and there should be no proptosis. Mild reliable patients may be treated orally with close follow-up; limited exam, toxicity, orbital signs, or failure to improve requires emergency imaging/evaluation.
Endophthalmitis
Severe pain, marked vision loss, hypopyon, absent red reflex, and recent ocular surgery/injection/trauma are red flags. Immediate ophthalmology/ED transfer is required for intravitreal therapy and possible vitrectomy.
Table 1. Diagnostic Signs and Symptoms of Common Causes of Red Eye — 2026
| Cause | Pain | Discharge | Vision | Key clue / action |
|---|---|---|---|---|
| Viral conjunctivitis | Mild irritation | Watery | Usually normal | Often bilateral sequentially; preauricular node; supportive care |
| Simple bacterial conjunctivitis | Mild | Mucopurulent | Usually normal | Lid matting; mild cases self-limited |
| Gonococcal conjunctivitis | Variable | Copious purulent | May decrease | Hyperacute; chemosis; emergency due corneal perforation risk |
| Allergic conjunctivitis | Itching > pain | Watery/mucoid | Normal | Bilateral; atopy; papillae; antihistamine/mast-cell stabilizer |
| Dry eye | Burning/gritty | Minimal | Fluctuating | Often chronic; improves with lubrication |
| Subconjunctival hemorrhage | None | None | Normal | Sharply demarcated blood; no corneal findings |
| Microbial keratitis | Moderate-severe | Variable | Often reduced | Photophobia; corneal infiltrate/defect; same-day ophthalmology |
| HSV keratitis | Pain/photophobia | Watery | May reduce | Dendritic fluorescein lesion; decreased corneal sensation |
| HZO | Pain | Watery | May reduce | V1 vesicular rash; ocular involvement may be delayed |
| Anterior uveitis | Aching | Minimal | Often reduced | Consensual photophobia; ciliary flush; cells/flare |
| Acute angle closure | Severe | Minimal | Reduced | Halos, nausea, corneal edema, mid-dilated pupil, high IOP |
| Episcleritis | Mild | None | Normal | Sectoral redness; self-limited |
| Scleritis | Severe/deep | None | May reduce | Boring pain; deep nonblanching injection; urgent referral |
| Preseptal cellulitis | Lid tenderness | None | Normal | Normal EOM, pupils, color vision; no proptosis |
| Orbital cellulitis | Moderate-severe | None | May reduce | Painful/restricted EOM, proptosis, chemosis; emergency |
| Endophthalmitis | Severe | None | Markedly reduced | Recent surgery/injection/trauma; hypopyon; emergency |
Disposition Pearls
- Immediate ED/ophthalmology: severe pain with vision loss, corneal infiltrate/ulcer, gonococcal disease, acute angle closure, orbital cellulitis, endophthalmitis, or toxic appearance.
- Same-day ophthalmology: suspected keratitis, anterior uveitis, scleritis, ocular HSV/VZV, significant contact-lens-associated red eye, or unexplained decreased visual acuity.
- Routine follow-up is reasonable for clearly uncomplicated surface disease when vision is normal and red flags are absent.
- Reevaluate promptly for any development of pain, photophobia, reduced vision, corneal change, or orbital signs.
Medicolegal Pearls
- Document visual acuity in all patients with eye complaints.
- Document corneal and anterior chamber findings and fluorescein findings when used.
- Document contact lens status and prior ocular surgery/procedure.
- Do not prescribe topical corticosteroids for an undifferentiated red eye.
- Do not dilate when acute angle closure is suspected.
- When a vision-threatening diagnosis cannot be excluded, arrange ophthalmic evaluation rather than relying on empiric treatment.
References
- Cheung AY, Choi DS, Ahmad S, et al. Conjunctivitis Preferred Practice Pattern. Ophthalmology. 2024;131(4):P134-P204.
- Lin A, Ahmad S, Amescua G, et al. Blepharitis Preferred Practice Pattern. Ophthalmology. 2024;131(4):P50-P86.
- Rhee MK, Ahmad S, Amescua G, et al. Bacterial Keratitis Preferred Practice Pattern. Ophthalmology. 2024;131(4):P87-P133.
- Amescua G, Ahmad S, Cheung AY, et al. Dry Eye Syndrome Preferred Practice Pattern. Ophthalmology. 2024;131(4):P1-P49.
- Gedde SJ, Chopra V, Vinod K, et al. Primary Angle-Closure Disease Preferred Practice Pattern. Ophthalmology. 2026;133(4):P153-P201.
- Centers for Disease Control and Prevention. Gonococcal Infections Among Adolescents and Adults: STI Treatment Guidelines. Current online guidance accessed 2026.
- Centers for Disease Control and Prevention. Chlamydial Infections: STI Treatment Guidelines. Current online guidance accessed 2026.
- American Academy of Ophthalmology EyeWiki. Orbital Cellulitis. Updated 2026.
- American Academy of Ophthalmology EyeWiki. Preseptal Cellulitis. Updated 2026.
- American Academy of Ophthalmology EyeWiki. Herpes Simplex Virus Keratitis. Current online review accessed 2026.
- American Academy of Ophthalmology EyeWiki. Herpes Zoster Ophthalmicus. Current online review accessed 2026.
- American Academy of Ophthalmology EyeWiki. Endophthalmitis. Updated 2026.