Red Eye

Most red eyes seen in primary care are not dangerous. The most common causes are:

• Viral conjunctivitis ("pink eye"). Watery discharge, gritty feeling, often starts in one eye and spreads to the other. Very contagious. Usually clears in 1-2 weeks. Antibiotic drops do not help.
• Bacterial conjunctivitis. Yellow or green discharge that crusts the lashes overnight. Often clears on its own in a week, faster with antibiotic eye drops. The line between viral and bacterial conjunctivitis is fuzzy in clinical practice, and management decisions are usually made on history and exam alone ⁴.
• Allergic conjunctivitis. Both eyes itchy, watery, and pink. Often with sneezing, runny nose, or other allergy symptoms. Treated with antihistamine eye drops, cool compresses, and avoiding triggers.
• Subconjunctival hemorrhage. A flat, bright red patch on the white of the eye from a tiny burst vessel. Painless, no vision change. Looks scary but harmless. Clears in 1-2 weeks.
• Dry eye disease. Burning, gritty, fluctuating vision, often worse on screens or in dry air. Treated with artificial tears, warm compresses, and lid hygiene.
• Blepharitis. Crusty, flaky lid margins with chronic mild redness. Treated with lid scrubs and warm compresses.
• Stye or chalazion. A tender lump on the eyelid with localized redness.

A small percentage of red eyes have serious causes that can permanently damage vision. Doctors look for these red flags during the initial evaluation ²:

• Bacterial or fungal keratitis. A corneal infection that can scar the cornea and cause blindness in 24-48 hours. Almost always painful, with light sensitivity and a white spot on the clear front of the eye. Contact lens wearers are at very high risk.
• Acute anterior uveitis (iritis). Deep ache, severe light sensitivity, blurry vision. Often associated with autoimmune disease. Needs steroid eye drops from an eye doctor.
• Scleritis. Severe boring pain that wakes the patient at night. The redness has a deep, dusky violet color. Often linked to systemic autoimmune disease. Patients with a sore red eye and joint pain, mouth ulcers, or rash may need a workup for systemic involvement ⁵.
• Acute angle-closure glaucoma. Severe eye pain, halos around lights, headache, nausea, and vomiting. The eye pressure goes dangerously high in hours. Needs emergency treatment.
• Open-globe injury. Any cut or penetrating injury to the eye is a true emergency. Cover the eye with a shield (not a patch) and go to the emergency room.
• Endophthalmitis. A serious infection inside the eye. Almost always after recent eye surgery or an injection. New eye pain, redness, or vision drop after recent eye surgery is an ocular emergencies presentation that needs same-day retina or ophthalmology care ³.
• Chemical burn. Acid or alkali in the eye. Rinse with copious water for 15-20 minutes immediately, then go to the ER.

Quality improvement projects in primary care show that structured red flag identification reduces missed sight-threatening diagnoses ⁶.

For a mild red eye with no red flags (no pain, no vision change, no contact lenses, no recent injury):

• Cool compresses — a clean cloth dampened with cool water, held over the closed eyes for 5-10 minutes a few times a day.
• Preservative-free artificial tears — 1 drop in the affected eye every few hours.
• Wash hands often — viral pink eye spreads easily. Do not share towels, pillowcases, or eye makeup.
• Stop contact lens wear until the eye is white and comfortable. Throw out the lenses you were wearing.
• Avoid eye makeup until things settle.
• Take out and store contacts properly using only fresh contact lens solution — never tap water or saliva.

Do NOT do these things:

• Do not use leftover steroid eye drops from a past illness — steroids can worsen herpes keratitis or fungal infection.
• Do not wear a tight eye patch. A patch traps bacteria; for an injury, use a hard plastic shield instead.
• Do not use redness-reducing drops (vasoconstrictor drops) for more than a day or two — they can cause rebound redness.

Same-day urgent eye care for any of these:

• Contact lens wearer with a red, painful eye.
• Moderate or severe eye pain.
• Sudden vision loss or blurry vision in the affected eye.
• Severe light sensitivity.
• Halos around lights with headache, nausea, or vomiting.
• Eye injury, chemical splash, or anything stuck in the eye.
• New pain or vision drop after recent eye surgery.
• Newborn under 28 days old with a red eye or discharge.
• Immunocompromised patient with a new red eye.

This-week eye doctor visit for:

• A red eye that is not getting better after a week.
• Recurring red eye episodes.
• Yellow or green discharge that crusts the lashes overnight.
• Recurrent stye-like lumps on the lid.

Worrisome red eye presentations like episcleritis are diagnosed in the primary care setting all the time, but should be referred to an eye doctor if they recur or do not respond to standard treatment ⁷.