Is CLARE an infection?

No. CLARE is a sterile (non-infectious) inflammatory response. It is triggered by bacterial toxins from normal ocular flora, not by active bacterial invasion of the cornea. The infiltrates seen in CLARE are collections of inflammatory white blood cells, not bacterial colonies.

Can a patient continue extended wear after a CLARE episode?

No. A CLARE episode indicates that the patient's cornea does not tolerate overnight lens wear. Even with higher-Dk lenses, recurrence is likely. The patient should be permanently converted to daily wear contact lenses.

How do you distinguish CLARE from microbial keratitis?

CLARE typically presents with small, peripheral infiltrates, minimal epithelial defect, mild to moderate pain, and no purulent discharge. Microbial keratitis usually involves a large central infiltrate with a significant epithelial defect, severe pain, and mucopurulent discharge. When in doubt, treat as microbial keratitis until proven otherwise.

Contact Lens Acute Red Eye (CLARE): Causes, Signs, and Management

What Is CLARE?

Contact Lens Acute Red Eye (CLARE) is an acute, non-infectious inflammatory reaction that occurs in contact lens wearers, most commonly after sleeping in lenses. Despite its alarming appearance, CLARE is not a true infection. It is a sterile inflammatory response triggered by the combination of corneal hypoxia and exposure to bacterial toxins trapped beneath the lens during overnight wear.

CLARE is one of the most common complications of extended wear contact lenses and serves as a clear clinical signal that overnight lens wear is compromising corneal health.

Causes and Mechanism

CLARE results from two simultaneous factors during overnight lens wear:

Corneal hypoxia: During sleep, the closed eyelid already reduces oxygen supply to the cornea. A contact lens further restricts oxygen, creating a hypoxic environment
Bacterial toxins: Normal commensal bacteria on the ocular surface, particularly Staphylococcus epidermidis and other gram-negative organisms, produce endotoxins. During open-eye wear, tear exchange flushes these toxins away. During sleep with a lens in place, the toxins become trapped between the lens and cornea

The combination of a stressed, oxygen-deprived cornea and concentrated bacterial toxins triggers an acute immune response. Inflammatory cells migrate into the corneal stroma, producing the characteristic sterile infiltrates.

CLARE is a sterile (non-infectious) inflammatory response, not an infection. The bacteria involved are normal ocular flora, and their toxins, not the organisms themselves, drive the inflammation. This distinction is critical because CLARE management differs from infectious keratitis.

Clinical Presentation

CLARE typically presents upon waking or shortly after the patient opens their eyes in the morning:

Unilateral or bilateral red eye: Often more prominent in one eye
Limbal and conjunctival injection: Redness concentrated around the limbus
Sterile corneal infiltrates: Small, white, focal inflammatory deposits in the peripheral or mid-peripheral cornea. These are collections of white blood cells, not bacterial colonies
Mild to moderate pain: Typically less severe than infectious keratitis
Tearing and photophobia: Reflexive responses to the inflammation
No significant discharge: Unlike infectious conditions, CLARE does not produce purulent discharge

Differentiating CLARE from Microbial Keratitis

The critical clinical challenge is distinguishing CLARE from infectious microbial keratitis, which requires urgent, aggressive treatment:

Feature	CLARE	Microbial Keratitis
Infiltrate location	Peripheral/mid-peripheral	Often central
Infiltrate size	Small, multiple	Large, single or coalescing
Epithelial defect	Minimal or none	Significant overlying defect
Pain level	Mild to moderate	Severe
Discharge	Minimal/watery	Mucopurulent
Anterior chamber reaction	Mild or none	Often present

Assuming all red eyes with infiltrates in contact lens wearers are CLARE. If there is a large central infiltrate with a significant overlying epithelial defect, severe pain, and mucopurulent discharge, treat as microbial keratitis until proven otherwise. Culture first, then treat aggressively.

Management

CLARE management is straightforward once the diagnosis is confirmed:

Discontinue lens wear immediately: Remove the contact lens and keep it for possible analysis
Discontinue extended wear permanently: CLARE is a clear indication that overnight wear is not appropriate for this patient
Supportive treatment: Preservative-free artificial tears for comfort
Consider prophylactic antibiotics: Some practitioners prescribe a short course of topical antibiotics to prevent secondary infection over the compromised corneal surface
Follow-up: Monitor resolution over 2-5 days. Infiltrates should begin clearing within 24-48 hours
Refit: After resolution, refit the patient with daily wear lenses only, preferably with high-Dk materials

Prevention

Use high-Dk/t silicone hydrogel lenses if extended wear is necessary
Encourage daily wear modality whenever possible
Ensure proper lens fit to allow adequate tear exchange
Educate patients about the risks of sleeping in lenses

A patient who experiences CLARE should be considered permanently unsuitable for extended wear. Even with higher-Dk lenses, the underlying susceptibility to overnight inflammatory reactions makes recurrence likely. Convert to daily wear and document the CLARE episode in the chart.

Key Takeaways

CLARE is a sterile inflammatory reaction, not an infection, caused by corneal hypoxia plus trapped bacterial toxins during overnight wear
Characterized by limbal redness, small peripheral sterile infiltrates, and mild to moderate pain upon waking
Must be differentiated from microbial keratitis, which presents with larger central infiltrates and more severe symptoms
Management centers on discontinuing extended wear permanently and refitting with daily wear lenses
Resolution typically occurs within 2-5 days after lens removal