Eye Infections

Eye infection covers a wide range. At one end sits viral conjunctivitis, unpleasant and contagious but self-limiting. At the other sit keratitis, endophthalmitis and orbital cellulitis, which can cost sight or worse within days.

The layer that is infected decides the risk. The conjunctiva heals without scarring; the cornea sits directly in the visual axis, so an infection there can leave a permanent scar over the pupil. Anything infecting the inside of the eye or the tissues around it is a hospital problem, not a drops problem.

• Redness with discharge, crusting or watering
• Gritty, burning or genuinely painful eye
• Light sensitivity and blurred or dropping vision
• A tender lump on the lid, or a swollen, hot eyelid
• Fever, or swelling that spreads across the cheek or brow

Viruses (adenovirus above all, and herpes simplex), bacteria (staphylococci, streptococci, and Pseudomonas in contact lens wearers), fungi after injury with plant material, and Acanthamoeba from water exposure in lenses.

Risk rises sharply with sleeping or swimming in contact lenses, topping up rather than replacing lens solution, an existing corneal abrasion, recent eye surgery, diabetes and a suppressed immune system.

Treatment follows the organism, so the diagnosis has to come first — that means an exam with fluorescein staining and, for a suspected corneal ulcer, a scrape for culture.

Bacterial conjunctivitis takes antibiotic drops; corneal ulcers take intensive fortified drops, sometimes hourly around the clock, with close follow-up. Herpes needs antivirals — and steroid drops alone can make it dramatically worse. Orbital cellulitis and endophthalmitis are admissions for intravenous antibiotics or injections into the eye.