editor's perspective
Corneal Infiltrates: What's the Difference?

Our colleagues in Australia and Canada and our friends across the planet have done great work to define and categorize contact lens related complication. These include contact lens peripheral ulcer (CLPU), contact lens induced acute red eye (CLARE), infiltrative keratitis, asymptomatic infiltrative keratitis, and asymptomatic infiltrates (Sweeney et al. Cornea; 2003). Of course there is also the most feared, microbial keratitis (MK) aka infectious corneal ulcer. Contact lens educators teach these terms to varying degrees while U.S. clinicians have adopted these terms to a varying extent as well.

At this past Southern Council of Optometry meeting, Bobby Christensen, OD, MBA, FAAO, mentioned in a lecture how he didn't like to use the term ulcer for the typical limbal infiltrate associated with contact lenses. Ulcer sounds far worse and looks far worse in a medical record than it should in most of these cases. I prefer this term: contact lens peripheral infiltrate (CLPI). At the recent AOA meeting I was asked to share something that was presented at a continuing education session. It is the fundamental approach to differential diagnosis of contact lens related infiltrative keratitis. It is also the basis for an ongoing study monitoring continuous wear. I hope you find it helpful and invite any comments.

• High Probability of microbial keratitis = 1+ infiltrates, >2mm in diameter AND either an anterior chamber reaction, or pain, or mucopurulent discharge, or positive culture. The presence of a scar is required when adequate follow-up is possible.
• High probability of infiltrative keratitis with etiology indeterminate = 1+ infiltrates with signs/symptoms not clearly meeting MK or SK (below).
• High probability sterile keratitis (aka CLPU or CLPI) = 1+infiltrates, < or = 1mm in diameter, outside the 6mm central zone, AND minimal anterior chamber reaction, AND no mucopurulent discharge, AND mild pain.

Robboy, in his review article in Eye and Contact Lens (2003) refers to Contact Lens-Associated Corneal Infiltrates (CLACI). He points out that beyond the contact lens related conditions and their association with cytokines, chemokines, adhesion molecules, and other molecular stimuli, that clinicians need to include in their differential diagnosis in these cases: Chlamydial disease including trachoma, and adneovirus, epidemic conjunctivitis.

It is difficult for any of us to define standard nomenclature, especially in this field which is ripe with diversity. Ongoing discussion to reach a common terminology is desirable -- if only we could.