Contact Lens Care
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Direct answer
Acanthamoeba keratitis is the reason the care rules are written as they are: every lens, whatever its schedule, is rubbed and rinsed on removal, disinfected overnight in a multipurpose solution or a peroxide system neutralised for a full six hours, and stored in a case that is emptied, rinsed and air-dried — and replaced every one to three months. Tap water, swimming, showering and sleeping in lenses are the standing prohibitions, because contaminated water and closed-eye wear convert a convenience product into a corneal ulcer risk. The wearer who returns with pain, redness, photophobia or reduced vision stops wearing the lenses and is examined the same day.
What you must remember
- Hands first: wash, rinse and dry on a lint-free towel before touching a lens; cosmetics go in after insertion, off before removal.
- Rub and rinse remains standard — about 10 seconds each side — even with "no-rub" multipurpose solutions; rubbing removes the biofilm disinfection cannot penetrate.
- Disinfection: multipurpose solution needs roughly 4–6 hours of soak; saline rinses only and disinfects nothing.
- Peroxide systems (3 per cent hydrogen peroxide) must neutralise — catalytic disc or timed tablet — for a minimum of about 6 hours; early insertion causes an excruciating chemical keratitis. Peroxide suits sensitive and allergic eyes.
- Cases: discard old solution (never top up), rinse with solution, air-dry, and replace the case every 1–3 months — biofilm-lined old cases are the commonest reservoir in microbial keratitis chains.
- No water: tap, well, pool and shower water carry Acanthamoeba; its keratitis presents with pain out of proportion to signs, a ring infiltrate and radial perineuritis, and is notoriously hard to treat.
- Wear discipline: respect replacement schedules, build daily hours gradually, and never sleep in lenses unless approved for extended wear — overnight wear multiplies microbial keratitis risk.
- Complications to recognise: giant papillary conjunctivitis (tarsal papillae, itching, mucus, intolerance), CLARE (acute red eye with infiltrates after closed-eye wear), sterile infiltrates, tight lens syndrome, neovascularisation beyond about 1.5 mm, and 3-and-9 o'clock staining with rigid lenses.
- Red flags — pain, redness, photophobia, discharge, blurred vision — mean stop, and same-day examination; patching a contact-lens-related ulcer is contraindicated.
The case that teaches every rule
A monthly silicone hydrogel wearer naps in her lenses and rinses the case under the tap "to keep it fresh". She wakes with a watering, photophobic right eye and reduced vision. Management follows the rules she broke: stop wear in both eyes; examine before anything reinserts — fluorescein shows a central defect with infiltrate; the lens and case go for microbiology where possible. This is presumed microbial keratitis, an urgent referral — and no patch, because a warm, occluded, hypoxic eye is an incubator.
Follow the case back to its origins: topped-up solution left the disinfectant diluted, the tap-rinsed case seeded a biofilm, the nap compressed wear into closed-eye physiology and starved the cornea. Each rule existed for one link of that chain. Once healed, the refit conversation is programmatic: daily disposables or a strict monthly routine, peroxide or a named solution, a dated case, water avoidance, and written red-flag instructions — because the patient who can recite the danger signs is the complication you never see again.
Where students slip
Three wrong answers recur. Peroxide timing: "an hour or two is enough" — neutralisation needs about six hours, and the direct-insertion injury is a chemical keratitis, not an allergy. Saline as a disinfectant: it rinses, nothing more. The water blind spot: candidates police lens hygiene but allow "rinsing the case under the tap" or "swimming with eyes closed" — both are Acanthamoeba doors, and the exam wants the named organism, its presentation and its resistance to treatment. On complications, do not blur GPC with CLARE: GPC is a chronic tarsal allergic reaction of both eyes with itching and papillae; CLARE is an acute inflammatory red eye with infiltrates, classically after overnight wear. And never patch a contact-lens-related corneal ulcer.
Frequently asked questions
Why must tap water never touch lenses or cases?
Tap water hosts Acanthamoeba, cause of a severe, often treatment-resistant keratitis; only sterile saline or multipurpose solution touches a lens or its case.
How long must peroxide systems neutralise before insertion?
A minimum of about six hours with the catalytic disc or tablet; early insertion causes acute chemical keratitis.
How often should lens cases be replaced?
Every one to three months, with daily emptying, solution-rinse and air-drying — aged cases develop biofilms that defeat disinfection.
What is giant papillary conjunctivitis?
A chronic allergic reaction of the upper tarsal conjunctiva — papillae, itching, mucus and lens intolerance — managed by enhanced hygiene, refit and mast-cell stabilisers.
What is CLARE?
Contact lens acute red eye — an inflammatory reaction with infiltrates and lacrimation, typically after overnight wear of tight lenses; it resolves with discontinuation and review.
What symptoms demand same-day assessment?
Pain, redness, photophobia, discharge or falling vision: the lens stops, both eyes are examined with fluorescein, and suspected ulcers are referred urgently — never patched.