Contact lens complications range from minor discomfort to sight-threatening infections. Recognizing these complications early and knowing when to escalate to the physician is one of the most critical skills for a CPO working in a contact lens practice.
Microbial Keratitis
Microbial keratitis is a bacterial (or occasionally fungal or Acanthamoeba) infection of the corneal stroma. It is the most serious contact lens complication and can cause permanent corneal scarring and vision loss. Risk factors include:
- Sleeping in lenses
- Poor lens hygiene
- Swimming in contact lenses
- Extended wear modalities
- Damaged or contaminated lens cases
Clinical features include severe pain, redness, photophobia, and a white or gray corneal infiltrate (opacification). The most common pathogens are Pseudomonas aeruginosa (particularly aggressive) and Staphylococcus aureus.
Corneal Hypoxia and Neovascularization
The cornea depends on atmospheric oxygen for its metabolic needs. Contact lenses act as a partial barrier to this oxygen supply. Corneal hypoxia (oxygen deprivation) causes:
- Corneal edema (microcysts, striae visible on slit lamp)
- Increased susceptibility to infection
- Limbal hyperemia (redness at the corneal periphery)
- Corneal neovascularization: New blood vessels grow from the limbus into the normally avascular cornea to try to supply more oxygen. Any neovascularization extending more than 1 to 2 mm into the cornea requires lens discontinuation or refitting with higher-Dk lenses.
Switching patients to silicone hydrogel lenses with high Dk/t values significantly reduces hypoxia-related complications.
Giant Papillary Conjunctivitis (GPC)
Giant papillary conjunctivitis (GPC), now also called contact lens-associated papillary conjunctivitis (CLPC), is an immune-mediated reaction to lens deposits or the lens material itself. Large papillae (bumps) develop on the upper tarsal conjunctiva (under the upper lid), causing:
- Itching, particularly when inserting or removing lenses
- Mucous discharge
- Lens awareness and reduced wearing time
- Lens movement on the eye (papillae grip the lens and cause it to shift upward)
Treatment includes lens cleaning with enzymatic cleaners, switching to daily disposables (fewer deposits), using a different lens material, or temporarily discontinuing lens wear while using mast cell stabilizer drops.
Contact Lens-Associated Red Eye (CLARE)
CLARE is an acute inflammatory reaction occurring in patients sleeping in extended-wear lenses. It presents with sudden waking from sleep with a painful, red eye. Unlike microbial keratitis, CLARE is typically sterile (inflammatory, not infectious) and resolves within 24 hours after lens removal. The cause is bacterial endotoxins trapped under the lens during sleep. Despite the dramatic symptoms, vision is usually preserved and the cornea has no dense infiltrate. Management is lens discontinuation and lubricating drops; topical antibiotics are sometimes added empirically.
Superior Epithelial Arcuate Lesion (SEAL)
A SEAL is an arcuate (curved) epithelial split in the superior cornea, caused by mechanical interaction between a tight-fitting or thick-edged soft lens and the superior cornea under the upper lid. It appears as a curvilinear staining pattern with fluorescein at approximately the 10 to 2 o'clock positions. Management involves refitting with a flatter or thinner-edged lens.
3 and 9 O'Clock Staining in GP Wearers
GP lens wearers commonly develop desiccation staining at the 3 and 9 o'clock positions on the cornea (the horizontal meridian). This occurs because the rigid lens disrupts normal blink coverage and tear distribution across those areas, causing epithelial drying. Management includes proper lens edge design, lubricating drops, and ensuring blink completeness.
Key Takeaways
- Microbial keratitis is the most serious complication; any painful red eye in a contact lens wearer is urgent and requires same-day evaluation.
- Corneal hypoxia from low-Dk lenses causes edema, microcysts, and neovascularization; silicone hydrogel lenses reduce this risk.
- GPC is an immune reaction causing papillae under the upper lid; daily disposables and enzymatic cleaning help.
- CLARE is an acute sterile inflammatory response from sleeping in extended-wear lenses; resolves with lens removal.
- Never advise a contact lens patient with pain, redness, and reduced vision to continue wearing their lenses.