How Do I Know If I Have Pink Eye?

Conjunctivitis is inflammation of the conjunctiva — the thin, clear membrane that covers the white of the eye and lines the eyelids. When it is irritated by a virus, bacteria, or allergy, its tiny blood vessels dilate and the eye turns pink, waters, and produces discharge. Because the cornea and the inside of the eye are usually not involved, true pink eye is uncomfortable but does not significantly blur vision or cause deep pain. That is exactly why pain, light sensitivity, or a real drop in vision should make you think beyond pink eye.

The three common types tell themselves apart by the company they keep.

• Viral conjunctivitis is the classic "pink eye": watery discharge, a gritty feeling, often starting in one eye and spreading to the other, frequently alongside or just after a cold or sore throat. It is very contagious.
• Bacterial conjunctivitis produces thicker yellow or green discharge that can glue the lashes shut in the morning, and the redness is often more pronounced.
• Allergic conjunctivitis itches — that is its signature — affects both eyes symmetrically, waters heavily, and travels with sneezing, a runny nose, and puffy lids during allergy season.

Several conditions imitate pink eye and matter more: dry eye and blepharitis cause chronic redness and burning; iritis causes aching pain and light sensitivity with redness concentrated in a ring around the iris; keratitis (a corneal infection, often contact-lens-related) causes pain and light sensitivity and can scar the cornea; and acute angle-closure glaucoma causes a painful, hard, red eye with halos and nausea. None of those should be waited out with pink-eye home care.

Be examined promptly — call (717) 637-1919, or seek emergency care after hours — if a red eye comes with any of the following:

• Moderate or severe eye pain, or marked light sensitivity
• Blurred vision that does not clear with blinking
• A white or cloudy spot on the cornea
• Intense redness concentrated around the colored part of the eye
• Contact lens wear
• Symptoms in a newborn, after eye trauma, or after chemical exposure
• No improvement after several days, or steady worsening

Vision is checked first, because true conjunctivitis rarely reduces it. The slit-lamp microscope then shows which tissue is inflamed: the conjunctiva alone (pink eye), the cornea (keratitis), the front chamber (iritis), or the lids (blepharitis). Fluorescein dye highlights corneal involvement, and the pattern of discharge, the story of exposure, and whether one or both eyes are involved usually identify the type without any lab work. When needed, eye pressure is measured to rule out angle-closure.

Viral pink eye runs its course over one to two weeks; cool compresses and artificial tears relieve symptoms while it does, and antibiotics do not help it. For bacterial conjunctivitis, mild cases often resolve on their own; a clinician may prescribe antibiotic drops or ointment when they are indicated. Allergic conjunctivitis responds to antihistamine/mast-cell-stabilizer drops, cool compresses, and managing the allergy itself. Careful hand hygiene, fresh towels and pillowcases, and discarding eye makeup protect the other eye and other people. Contact lens wearers should stay out of lenses until the eye is fully quiet and cleared.

• Do not use leftover prescription drops — steroid drops can make a herpes or fungal infection dramatically worse.
• Do not keep wearing contact lenses in a red eye, and throw away the current pair and case.
• Do not share towels, washcloths, or pillowcases while symptomatic.
• Do not rub the eyes; it spreads infection and worsens allergy.
• Do not wait on pain, light sensitivity, or vision change — those are not pink-eye symptoms.