International Insight Into Managing Cornea Infiltrates
By Leo Semes, OD, FAAO
When a contact lens-wearing patient presents with an irritated red eye, the culprit is often a peripheral infiltrate (a.k.a., peripheral ulcer, corneal infiltrate, etc.). Differentiating this from infectious keratitis is clearly priority No. 1. We know that peripheral infiltrates in the setting of contact lens wear have distinguishing clinical characteristics. These include lesser degree of symptoms, less redness, longer duration from onset of symptoms to presentation, smaller size, more numerous, peripheral location, and, generally, absence of an anterior chamber reaction (Baum and Dabiezes, 2000). While there are other associated risk factors for corneal infiltrates (e.g., ocular trauma and surface disease, prior ocular surgery, or herpetic eye disease [Mah, 2010]), the most likely to be encountered in primary eyecare practice is related to contact lens wear.
When Standard Treatment Options Aren't Available
Confronted with a suspicious presentation in a contact lens wearer, what is the appropriate approach? In the United States, the nearly reflex reaction is to manage the condition with topical steroid/antibiotic combination drops. Examples might include Tobradex ST (dexamethasone 0.05%, tobramycin 0.3%, Alcon) or Zylet (loteprednol etabonate 0.5%, to-bramycin 0.3%, Bausch + Lomb). But this is a luxury that some of our Australian colleagues, for example, may not enjoy. I recently had the opportunity to participate in lectures sponsored by the University of New South Wales (UNSW) in Sydney, Australia. Optometrists there do not have access to commercial antibiotic/steroid combinations. This situation offers an opportunity to step back and consider our options.
Inflammation causes the response with corneal infiltrates. Logically, in the absence of a combination drop, a steroid would be preferred to antibiotic monotherapy. In many cases this may be sufficient to resolve the situation (Baum and Dabiezes, 2000; Mah, 2010). But, for the sake of reassurance, many clinicians would want prophylactic antibiotic coverage. This leads to another decision.
What would be the prophylactic antibiotic of choice against microbial keratitis in a contact lens wearer? My most feared cause of microbial keratitis is the gram-negative organism Pseudomonas aeruginosa for a number of reasons (O’Brien, 2003; Green et al, 2008). Because this is also the most prevalent organism associated with contact lens-related keratitis, the antibiotics of choice might include the fluoroquinolones or fortified tobramycin (but not gentamycin) (Willcox, 2012; Mohammadpour et al, 2011). So another decision then needs to be made.
Which antibiotic for prophylaxis? Clinicians should consider close follow up of patients who have peripheral infiltrates, especially when prescribing monotherapy with a topical steroid. Strains of P. aeruginosa are reported to have developed resistance to tobramycin, making a fluoroquinolone the better choice (Willcox, 2012). But no combination that contains a fluoroquinolone antibiotic and a steroid is available commercially. Therefore, selecting a commercially available product containing a steroidal component along with tobramycin, such as the two mentioned above, makes the most logical choice. CLS
The inspiration for this column came from Mr. Mark Roth of Melbourne and Dr. Yin Li of the University of Alabama at Birmingham School of Optometry.
To obtain references for this article, please visit http://www.clspectrum.com/references.asp and click on document #203.
|Dr. Semes is a professor of optometry at the UAB School of Optometry. He is a Speakers' Bureau member, advisor or consultant to Alcon, Allergan, ArcticDx, B+L, MedOp, Merck, OptoVue, and Zeiss.|