Red eyes occur when superficial or deeper blood vessels on the eye become dilated due to irritation, inflammation, or pressure changes. The severity and associated symptoms help determine the cause.
Frequent Causes
Mild redness often comes from dry eye, allergic or viral conjunctivitis, and minor irritation such as contact lens wear or environmental factors. More serious conditions include uveitis, scleritis, acute glaucoma, and corneal infection or ulcer.
- Painless redness with discharge commonly reflects conjunctivitis
- Redness with significant pain, light sensitivity, or blurred vision warrants urgent review
- Localised bright red patches may be harmless subconjunctival haemorrhages
- Systemic diseases and medications can also influence eye redness
Clinical Importance
While many red eyes are self‑limiting, some are sight‑threatening if untreated. A professional examination distinguishes benign from urgent causes.
- Avoid over‑the‑counter whitening drops that may mask symptoms
- Contact lens wearers with a red, painful eye should remove lenses and seek care promptly
- Chemical or thermal injuries require immediate irrigation and emergency assessment
- Recurrent redness may indicate chronic surface or lid disease
