Painful red eye in a contact lens wearer three hours from tertiary care
Amelia, 27, works on a dairy farm 3 hours from the nearest ophthalmology service. She wears daily disposable soft contact lenses and admits to sleeping in them two or three nights a week. She presents on a Friday afternoon with a 2-day history of right eye pain, photophobia and watering. Right VA is 6/12, left 6/6. Slit lamp shows a 2.5 mm round stromal infiltrate about 1.2 mm from the visual axis with an overlying epithelial defect, mild circumcorneal injection, 1+ anterior chamber cells and no hypopyon. IOP is 16 mmHg. She removed the lens this morning and brought it in. She has no history of ocular trauma, herpes simplex or previous keratitis. The clinic has a slit lamp, fluorescein, topical fluoroquinolone samples and a phone, but no after-hours ophthalmology cover until Monday.
1. What is your leading diagnosis and which alternatives must you actively exclude? Justify your reasoning from the findings.
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The leading diagnosis is contact lens-related bacterial keratitis. The infiltrate is focal, round, larger than 1 mm, associated with an overlying epithelial defect, mild anterior chamber reaction and reduced acuity. Overnight soft lens wear is the strongest risk factor, and the absence of trauma does not exclude bacterial infection.
Alternatives to exclude actively:
- Acanthamoeba keratitis: consider if pain is out of proportion, if there is a ring infiltrate, radial keratoneuritis, poor response to antibiotics, or a history of tap water rinsing or swimming in lenses. Overnight wear is a risk factor, so this cannot be dismissed.
- Fungal keratitis: relevant because she works on a farm, although there is no vegetative injury. Fungal ulcers tend to have feathery margins, slower onset and less purulent reaction; they may not respond to antibacterial treatment.
- Herpes simplex keratitis: check for a dendritic or geographic epithelial defect, reduced corneal sensation, prior cold sores and previous episodes. The round stromal infiltrate is not typical, but it must be considered before starting a steroid, which should not be used here.
- Marginal keratitis: usually multiple small peripheral infiltrates with staphylococcal lid disease, minimal anterior chamber reaction and a clear cornea between the infiltrate and limbus. This is a single larger infiltrate with an epithelial defect and cells, so microbial keratitis is more likely. The location 1.2 mm from the visual axis and the anterior chamber reaction raise the stakes: this is sight-threatening until proven otherwise.
2. Outline your immediate management, including prescribing, contact lens advice, review and criteria for urgent referral. Assume you hold New Zealand therapeutic prescribing rights.
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Immediate priorities are to start intensive topical antibacterial treatment, remove the lens reservoir and arrange safe review.
- Prescribing: start a topical fluoroquinolone, for example moxifloxacin 0.5% or ofloxacin 0.3%, one drop every hour while awake. The frequency reflects the size, location and anterior chamber reaction. If I did not hold therapeutic prescribing rights, I would refer urgently rather than delay treatment.
- Contact lens advice: discard the current lens, the case and any opened daily lenses. No lens wear until the cornea is healed and I have reviewed it. Reinforce hand hygiene and no tap water exposure.
- Do not patch the eye and do not prescribe a topical steroid. Patching can worsen infection and steroids can impair defence, especially if herpes or fungus is present.
- Review: see her within 24 hours. In a rural setting I must be honest about whether that is achievable. If I cannot guarantee 24-hour review, or if she cannot return, I should refer the same day to ophthalmology or arrange local urgent review.
- Referral thresholds: worsening pain or vision, enlarging infiltrate, new hypopyon, increasing anterior chamber reaction, endothelial plaque, IOP rise, no improvement by 24-48 hours, or any suspicion of acanthamoeba or fungal disease. A central or large infiltrate also warrants ophthalmology involvement for possible corneal scrape.
- Safety net: give written instructions and an after-hours contact number. Document that she understands the risk of permanent visual loss if treatment fails.
3. What documentation and communication steps are required, and how would you handle the fact that the patient is 3 hours from tertiary care?
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Document the history, overnight wear, visual acuity, slit lamp findings including size and distance from the visual axis, anterior chamber reaction, IOP, lens type and wearing habits. Record the diagnosis, differential, treatment, dosing, review interval, contact lens advice and the safety-net advice given.
Because she is 3 hours from tertiary care, I would:
- confirm a reliable phone number and a plan for her to call if pain or vision worsens;
- check whether a local GP or rural hospital could provide after-hours assessment;
- phone ophthalmology on Friday afternoon to discuss the case and agree a threshold for weekend transfer, rather than waiting until Monday;
- consider whether she can stay locally for 24-hour review rather than travelling home and back;
- record her informed consent to treatment and her understanding of the review plan.
Communication should be patient-centred and plain: explain that this is a corneal infection, not simple conjunctivitis, and that the drops are needed frequently. I would avoid blaming her for sleeping in lenses. I would also ask about barriers such as travel, cost and farm responsibilities, because these affect whether the plan is realistic. If she declines the plan, I would document informed refusal, provide the safety net and offer urgent referral.