Conjunctival injection is dilation of the superficial blood vessels in the conjunctiva, giving a bright red appearance. It usually indicates surface irritation or inflammation.
Causes
Infective or allergic conjunctivitis, dry eye, blepharitis, and minor trauma commonly produce conjunctival injection. Less often, foreign bodies, chemical exposure, or contact lens complications are responsible.
- Redness is often more intense in the fornices and away from the cornea
- Discharge, itching, or grittiness frequently accompany injection
- Systemic infections and viral illnesses may include injected eyes
- Chronic injection can result from long-term drop use or ocular surface disease
Clinical Significance
While many causes are benign, distinguishing simple conjunctivitis from early keratitis or uveitis is important. Examination looks for corneal staining, anterior chamber cells, and focal tenderness.
- Mild cases may be managed with lubricants and, when appropriate, topical therapy
- Contact lens wear should stop until serious causes are excluded
- Photophobia or vision loss with injection requires urgent assessment
- Public health advice may be needed for contagious conjunctivitis
