Red eye without pain: what to know

Small surface blood vessels can widen after dryness, dust, smoke, rubbing, lack of sleep, or exposure to a chemical or cosmetic. Conjunctivitis presents with redness and may also cause watering, crusting, discharge, or irritation. Allergic conjunctivitis commonly includes itching and watering after exposure to an allergen. A sharply defined bright-red patch on the white of the eye can follow a tiny surface blood vessel breaking, sometimes without discomfort.

A painless appearance is reassuring only in a limited way: it does not rule out a developing problem. The extent of redness, vision, discharge, light sensitivity, injury, and contact lens use are relevant.

Avoid rubbing the eye and pause eye makeup until the redness settles. Rinse away dust or a mild irritant with clean water or sterile saline. Wash your hands frequently and do not share towels, cosmetics, or eye drops. Remove contact lenses and leave them out while the eye is red. A cool compress may reduce irritation. Do not use redness-relief or prescription drops left over from another episode without advice, because they may be unsuitable for the current cause.

Seek prompt care if redness is joined by blurred or reduced vision, light sensitivity, discharge with significant swelling, a foreign-body sensation, injury, chemical exposure, or contact lens use. Get urgent help for sudden vision loss or rapid worsening. If the eye remains red, keeps recurring, or you develop new symptoms, arrange a primary-care or eye examination even if pain has not appeared.

Ask whether the redness is on the surface only, whether allergy or conjunctivitis fits the pattern, and whether you need an eye examination. Share when it began, whether one or both eyes are affected, any discharge or light sensitivity, recent rubbing or exposure, medicines, and contact lens use.