The eye examination begins with vision

“Red eye” is a sign, not a diagnosis. Conjunctivitis is common, but pain, photophobia, reduced vision, corneal opacity, abnormal pupil, elevated pressure, trauma, contact-lens use, or neurologic findings may indicate vision-threatening disease.

The most important urgent-care habit is to measure and document visual acuity in each eye before treatment whenever possible. Vision is the ophthalmic vital sign. If acuity cannot be measured, document why and whether the patient can count fingers, detect hand motion, or perceive light.

Immediate emergencies

Arrange immediate irrigation, emergency transfer, or same-day ophthalmologic care for:

• Chemical exposure—begin irrigation immediately before completing history or acuity
• Suspected open globe, penetrating injury, irregular or peaked pupil, extrusion, positive Seidel sign, or high-velocity projectile injury
• Sudden monocular or binocular vision loss, new field defect, curtain or shadow, or central visual distortion
• Severe eye pain with reduced vision, corneal opacity or infiltrate, hypopyon, or contact-lens-associated keratitis
• Painful red eye with headache, nausea, halos, mid-dilated pupil, or acute angle-closure concern
• Proptosis, ophthalmoplegia, pain with eye movement, reduced vision, afferent pupillary defect, or orbital cellulitis concern
• Retinal artery occlusion, retinal detachment, optic neuritis, temporal arteritis, or acute neuro-ophthalmic deficit
• Hyphema, traumatic iritis with concerning findings, retrobulbar hemorrhage, or significant blunt trauma
• Endophthalmitis after surgery or injection
• Herpes zoster involving the eye, tip of nose, vision, cornea, or intraocular structures
• Severe headache or focal neurologic symptoms accompanying visual change

Do not instill drops, patch, manipulate, or measure intraocular pressure when open globe is suspected. Shield without pressure, keep the patient from eating or drinking, control nausea, update tetanus as appropriate, and arrange emergent ophthalmologic care.

Focused history

Clarify which eye, exact onset, sudden versus gradual change, pain, photophobia, itching, foreign-body sensation, discharge, tearing, vision loss, flashes, floaters, curtain, diplopia, halos, headache, nausea, trauma, chemical exposure, and recent respiratory illness.

Ask about contact lenses: type, overnight wear, water exposure, hygiene, last use, and whether lenses were removed. Contact-lens use substantially changes the risk of microbial keratitis.

Review prior eye disease, glaucoma, surgery, injections, herpes or zoster, immune suppression, diabetes, autoimmune disease, sickle cell disease, anticoagulation, medications, and topical drops. Ask about occupational grinding, drilling, hammering metal, yard work, and UV exposure.

For transient or sudden vision loss, assess stroke/TIA symptoms, giant-cell arteritis symptoms, vascular risk, migraine features, and whether the deficit was monocular or binocular.

Core urgent-care eye examination

Visual acuity

Test each eye separately with corrective lenses if available. Use pinhole to assess refractive contribution. Do not record “vision normal” based only on conversation or gross tracking.

External and pupil examination

Inspect lids, lashes, lacrimal region, conjunctiva, sclera, cornea, anterior chamber, and surrounding face. Assess pupils for size, shape, reactivity, symmetry, and relative afferent pupillary defect.

Motility and fields

Assess extraocular movements, diplopia, pain with movement, proptosis, and gross visual fields. Orbital pain with movement plus fever or sinus disease is not simple conjunctivitis.

Fluorescein and magnification

Use cobalt-blue or appropriate illumination to inspect epithelial defects, dendritic patterns, foreign bodies, and leakage. Evert the upper lid when a retained foreign body is possible and open globe is not suspected. A vertical linear abrasion suggests material under the lid.

Intraocular pressure

Measure pressure when glaucoma or pressure-related disease is possible and equipment and training are available. Do not measure it when open globe is suspected. A normal pressure does not exclude every serious eye disorder.

Pattern-based red-eye differential

Conjunctivitis

Viral conjunctivitis often causes watery discharge, irritation, and contagious spread, frequently with respiratory symptoms. Most adult acute infectious conjunctivitis is viral and self-limited; antibiotics are not required.[1]

Bacterial conjunctivitis more often causes mucopurulent discharge and eyelid matting, but findings overlap. Hyperacute purulence, severe swelling, pain, or vision change raises concern for gonococcal disease and corneal involvement.

Allergic conjunctivitis is typically bilateral and prominently itchy, with watery or stringy discharge. Itching supports allergy but does not override pain, photophobia, or vision loss.

Conjunctivitis should not cause substantial pain, true photophobia, corneal opacity, or meaningful visual reduction after discharge is cleared. Those findings require a broader diagnosis.

Keratitis and corneal ulcer

Microbial keratitis can progress rapidly to scarring, perforation, and blindness. Contact-lens users with pain, photophobia, blurred vision, discharge, corneal opacity, or infiltrate require immediate lens removal and urgent ophthalmologic evaluation. CDC notes that bacterial keratitis can cause vision loss or blindness if untreated.[2]

Water exposure with contact lenses raises concern for Acanthamoeba, which can cause severe pain and permanent vision loss.[3] Vegetative trauma raises fungal concern. Do not prescribe topical corticosteroids for an undiagnosed red eye; steroids can worsen herpes, fungal, bacterial, and amebic disease.

Anterior uveitis

Uveitis often causes deep ache, consensual photophobia, ciliary flush, reduced vision, and a small or irregular pupil. Slit-lamp examination may show cells and flare. Treatment typically requires ophthalmology-directed cycloplegic and topical steroid therapy after infectious keratitis is excluded.

Acute angle closure

Severe unilateral pain, headache, nausea or vomiting, halos, cloudy cornea, reduced vision, and a mid-dilated poorly reactive pupil are classic warnings. This requires immediate pressure-lowering treatment according to protocol and emergent ophthalmology. Do not simply give an antiemetic and discharge because nausea improves.

Scleritis versus episcleritis

Episcleritis is often mild and self-limited. Scleritis produces severe deep boring pain, tenderness, and possible vision threat, often associated with systemic autoimmune disease. Pain with eye movement or failure of superficial vessels to blanch should heighten concern and prompt ophthalmologic evaluation.

Corneal abrasion and foreign body

Abrasion typically causes pain, tearing, photophobia, and foreign-body sensation after trauma. Document visual acuity, fluorescein size and location, pupil, anterior chamber, lid eversion, and absence of infiltrate or open globe.

Small uncomplicated abrasions often heal within 24–72 hours. Provide pain control and topical antimicrobial prophylaxis based on risk and local guidance. Contact-lens wear requires antipseudomonal coverage and closer follow-up. Stop contact lenses until healed and cleared; discard the implicated lenses and case as appropriate.

Do not prescribe topical anesthetic for unsupervised home use unless following a specific current protocol with tightly selected patients and follow-up; misuse can cause toxic keratopathy and delayed healing. Routine patching is generally avoided, especially with contact-lens injury or infection risk.

Superficial foreign bodies may be removed only with adequate visualization, equipment, patient cooperation, and clinician competence. High-velocity metal-on-metal injury may penetrate despite a subtle surface finding. A residual rust ring or deep/central object warrants ophthalmology.

Chemical eye injury

Irrigation is the treatment and must not wait. Remove contaminated contact lenses and particulate material when safe. Use copious isotonic fluid or clean water if necessary and continue until ocular-surface pH is neutral and remains stable after a pause. Alkali injuries may penetrate rapidly.

After irrigation, assess acuity, pupils, fluorescein uptake, limbal ischemia, pressure when safe, and associated facial injury. Contact Poison Control or occupational resources for the specific chemical, but do not pause irrigation to make the call. Significant burns require emergent ophthalmology.

Blunt and penetrating trauma

Assess mechanism, projectile velocity, protective eyewear, vision, pupils, motility, hyphema, globe contour, and orbital signs. Avoid pressure on a suspected ruptured globe. CT orbit may be required; MRI is contraindicated when metallic foreign body is possible.

Hyphema can rebleed and elevate pressure. Elevate the head, protect the eye, avoid NSAIDs when bleeding risk matters, restrict activity, and obtain urgent ophthalmology. Sickle cell disease or trait changes pressure-related risk and management.

Diplopia, restricted movement, infraorbital numbness, enophthalmos, or nausea/bradycardia with eye movement may signal orbital fracture or muscle entrapment. Children can have “white-eye” blowout fractures with little bruising but dangerous entrapment.

Eyelid and periocular complaints

Hordeolum is an acute focal tender eyelid-gland infection; chalazion is usually a chronic nontender obstruction. Warm compresses and lid hygiene are initial care for uncomplicated lesions. Recurrent or atypical lesions require ophthalmology evaluation.

Preseptal cellulitis causes lid erythema and swelling without orbital signs. Pain with eye movement, ophthalmoplegia, proptosis, reduced vision, afferent pupil defect, severe headache, or toxicity suggests orbital cellulitis and requires emergency imaging and intravenous therapy.

Eyelid lacerations involving the margin, canaliculus, levator, medial canthus, orbital fat, or significant tissue loss require specialist repair. Always exclude globe injury first.

Sudden vision change, flashes, and floaters

New flashes, floaters, or a curtain/field defect may represent posterior vitreous detachment, retinal tear, or detachment. A dilated retinal examination is required urgently; a normal nondilated urgent-care view cannot exclude peripheral retinal disease.

Sudden painless monocular vision loss may indicate retinal artery occlusion, retinal vein occlusion, vitreous hemorrhage, retinal detachment, or ischemic optic neuropathy. Treat retinal artery occlusion as a stroke-equivalent emergency requiring immediate ophthalmologic and vascular evaluation.

In patients over 50 with new headache, scalp tenderness, jaw claudication, polymyalgia symptoms, or vision change, consider giant-cell arteritis. Do not delay emergency corticosteroid treatment and specialty evaluation when suspicion is high while waiting for outpatient follow-up.

Contact-lens safety

Contact lenses should be removed immediately with unusual pain, redness, photophobia, or blurred vision. Do not resume wear until cleared. CDC recommends avoiding sleeping in lenses unless directed, keeping lenses away from water, using fresh disinfecting solution, and replacing cases regularly.[4]

A contact-lens wearer with “conjunctivitis” deserves corneal inspection and acuity. The consequence of missing a corneal ulcer is far greater than the inconvenience of same-day ophthalmology.

Medication safeguards

• Topical corticosteroids: Do not initiate for an undiagnosed red eye without ophthalmologic guidance; they can worsen infection and raise pressure.
• Topical anesthetics: Use diagnostically and procedurally; avoid casual take-home prescribing.
• Antibiotics: Match to suspected anatomy and risk. Ointment blurs vision; counsel against driving until clear.
• Vasoconstrictor “redness” drops: Repeated use can cause rebound redness and mask progression.
• Cycloplegics and pressure agents: Require diagnosis-specific contraindication review and follow-up.
• Systemic analgesics: Review renal, hepatic, pregnancy, anticoagulation, and GI risks.

Disposition and follow-up

Same-day ophthalmology is appropriate for reduced acuity, significant pain or photophobia, corneal lesion, contact-lens-associated pain, abnormal pupil, intraocular inflammation, pressure concern, trauma, sudden flashes/floaters, or uncertain diagnosis with vision risk.

Emergency precautions include any vision reduction, increasing pain, photophobia, corneal white spot, worsening swelling, fever, pain with eye movement, new diplopia, severe headache, nausea, flashes, floaters, curtain, or neurologic symptoms.

Simple viral conjunctivitis often improves over one to two weeks. Small abrasions usually improve within 24–72 hours. Lack of expected improvement is a diagnostic signal, not merely a reason to add another drop.

Documentation

Record acuity in each eye, correction used, pupils, afferent defect, fields, motility, pain with movement, external findings, corneal clarity, fluorescein findings, anterior chamber, pressure when measured, and contact-lens history. Include mechanism and tetanus status for trauma.

State dangerous diagnoses considered, medication risks, consultation, follow-up timing, contact-lens restrictions, and precise return precautions.

Example medical-decision-making language

Patient has bilateral itching and watery discharge with preserved corrected visual acuity, normal pupils, full painless extraocular movements, clear corneas, no fluorescein uptake, no photophobia, no contact-lens use, and no vision change. Findings favor uncomplicated allergic conjunctivitis. Keratitis, abrasion, uveitis, acute angle closure, orbital cellulitis, and open globe were considered but are not supported currently. Allergen avoidance, topical therapy, follow-up, and emergency precautions for pain, photophobia, corneal opacity, or vision change were provided.

Adapt to the actual encounter; never document findings that were not assessed.

Coding considerations

Examples include H10.9 conjunctivitis, unspecified; H57.10 ocular pain, unspecified eye; H53.8 other visual disturbances; S05.00XA injury of conjunctiva and corneal abrasion without foreign body, unspecified eye, initial encounter; T15.90XA foreign body on external eye, unspecified, initial encounter; H00.019 hordeolum externum, unspecified eye/eyelid; and H40.219 acute angle-closure glaucoma, unspecified eye.

Use laterality, eyelid, cause, complication, and encounter phase. Procedure families may include foreign-body removal, irrigation, tonometry, and fluorescein examination depending on setting and payer rules. Verify current ICD-10-CM and CPT descriptors.

Clinical pearls

• Visual acuity is the eye vital sign.
• Pain, photophobia, or reduced vision is not routine conjunctivitis.
• Irrigate chemical exposures before completing the history.
• Never measure pressure or manipulate a suspected open globe.
• Contact-lens pain is microbial keratitis until safely excluded.
• Steroid drops can turn a manageable infection into a vision-threatening one.
• A nondilated examination cannot exclude a peripheral retinal tear.
• Remove contact lenses and keep them out until cleared.
• Corneal anesthetic relief localizes surface pain but does not prove a benign cause.
• Hyperacute purulence needs gonococcal and corneal consideration.
• Pain with eye movement and proptosis are orbital red flags.
• Sudden painless vision loss is an emergency even when the eye is not red.

Conclusion

Safe ophthalmic urgent care begins with visual acuity, followed by pupils, motility, fields, corneal examination, and targeted pressure measurement. The clinician must distinguish superficial irritation from corneal, intraocular, orbital, retinal, vascular, and neurologic disease.

Immediate irrigation saves tissue in chemical burns. Eye shielding and nonmanipulation protect an open globe. Same-day ophthalmology protects vision in keratitis, uveitis, pressure crisis, retinal symptoms, and unexplained acuity loss. When urgent care cannot fully examine the structure at risk, escalation is part of the examination—not a failure of it.

References

1. Centers for Disease Control and Prevention. Clinical overview of pink eye [Internet]. Atlanta: CDC; 2024 Apr 15 [cited 2026 Aug 14]. Available from: https://www.cdc.gov/conjunctivitis/hcp/clinical-overview/index.html
2. Centers for Disease Control and Prevention. What causes bacterial keratitis [Internet]. Atlanta: CDC; 2025 May 27 [cited 2026 Aug 14]. Available from: https://www.cdc.gov/contact-lenses/causes/what-causes-contact-lens-related-bacterial-keratitis.html
3. Centers for Disease Control and Prevention. Clinical overview of Acanthamoeba keratitis [Internet]. Atlanta: CDC; 2025 Mar 27 [cited 2026 Aug 14]. Available from: https://www.cdc.gov/acanthamoeba/hcp/clinical-overview-acanthamoeba-keratitis/index.html
4. Centers for Disease Control and Prevention. Preventing eye infections when wearing contacts [Internet]. Atlanta: CDC; 2025 May 27 [cited 2026 Aug 14]. Available from: https://www.cdc.gov/contact-lenses/prevention/index.html
5. American Academy of Ophthalmology. On-call ophthalmology [Internet]. San Francisco: AAO [cited 2026 Aug 14]. Available from: https://eyewiki.aao.org/On_Call_Ophthalmology