Contact Lens Practice
What this domain tests
Contact lens questions test fitting principles, material selection, care systems, hygiene counselling and complication triage. New Zealand candidates should be able to distinguish benign lens-related findings from microbial keratitis and to advise on safe wear.
Core rules and concepts
- Soft lens oxygen transmission depends on material, thickness and water content; extended wear raises hypoxic and infection risk.
- Rigid and scleral lenses require correct sagittal depth and edge clearance; orthokeratology requires topographic assessment and follow-up.
- Water exposure, poor hand hygiene and overnight wear are major risk factors for microbial keratitis.
- Corneal infiltrates may be sterile or infectious; pain, photophobia, anterior chamber reaction and overlying epithelial defect raise concern.
- Advise patients to cease lens wear and bring lenses, cases and solutions when infection is suspected.
Worked example
A soft lens wearer presents with a painful red eye, photophobia and a focal corneal infiltrate with an epithelial defect. Reasoning: microbial keratitis must be assumed until reviewed. Advise immediate cessation of lens wear, do not patch the eye, arrange same-day ophthalmology assessment, and document lens type, wear schedule and hygiene. Prescribing a steroid or an antibiotic without assessment is unsafe.
Traps that cost marks
Reassuring a painful lens wearer without checking for an epithelial defect; patching a suspected microbial keratitis; failing to ask about swimming or showering in lenses; not documenting the lens and solution type.
Key points
- Pain, photophobia and an epithelial defect suggest microbial keratitis.
- Cease lens wear and refer same day when infection is suspected.
- Do not patch a suspected corneal infection.
- Water exposure and overnight wear increase risk.
- Record lens type, wear schedule and hygiene advice.