Thursday, April 13, 2006

CLPU (Contact Lens-Induced Peripheral Ulcer)

CLPU (contact lens peripheral ulcer) (Courtesy: CCLRU/LVPEI Guide to Corneal Infiltrative Conditions)

CLPU is a unilateral response of the cornea occurring as a result of colonization of contact lens surfaces by pathogenic Gram-positive bacteria, primarily Staphylococcus aureus and S. epidermidis.

Although seen with daily wear lens use, CLPU is more commonly observed with EW usage. Toxins released by the bacteria give rise to a whitish/gray focal anterior stromal infiltrate in the periphery or mid-periphery of the cornea. The round infiltrate can range in size from 0.1mm to 2.0mm, and during the acute presentation will show a full-thickness loss of epithelium. Symptoms may be absent, or may be significant with moderate foreign-body sensation, redness and tearing.

Symptoms rapidly decrease, and the epithelium resurfaces over the lesion, leaving a well-demarcated grayish scar. This scar often assumes a "bulls-eye" appearance and gradually fades after six months. A common clinical observation in contact lens practice is the presence of a newly discovered round scar in the peripheral cornea of an established patient wearing EW hydrogel lenses. This shows that the inflammatory events associated with CLPU are often so mild as to escape patients' attention. Approximately 50% of CLPUs present as scars in the absence of symptoms.

Patients who experience repeat episodes of CLPU are likely to have high levels of S. aureus and/or S. epidermidis on their lids and lashes. Overnight lens wear is best avoided in these patients. CLPUs are seen in patients wearing EW hydrogel lenses and CW silicone hydrogels. The elimination of hypoxia does not eliminate the risks of this complication.

Differential Diagnosis

The differential diagnosis for CLPU includes: early MK, marginal keratitis, and corneal phlyctenulosis. Because MK is sight threatening, it is imperative to distinguish it from the benign CLPU. The features of MK that clinically differ from CLPU include:
  • Increasing severity of signs and symptoms after lens wear is discontinued.
  • Irregular infiltrate with raised edges; satellite lesions are common.
  • Mucopurulent discharge, adherent to the lesion.
  • Lid edema.
  • Severe diffuse bulbar and limbal hyperemia.
  • Endothelial reaction.
  • Marked anterior chamber reaction (flare and cells, possible hypopyon)
Unlike MK, CLPUs have milder symptoms and quickly resolve with lens discontinuation, in the absence of therapeutic intervention. However, even though CLPU is non-infectious, the similarity between an active CLPU and an early peripheral MK dictates conservative management for CLPUs. This involves not only discontinuing lens wear, but also prescribing a broad-spectrum topical fluoroquinolone antibiotic (preferably fourth generation, which has good Gram-positive coverage), and extremely close monitoring over the first 24-hour period. (Be sure to schedule an appointment for a one-day follow-up and arrange for a telephone call several hours after seeing the patient to ensure that symptoms are not worsening.)

CLPUs differ from peripheral corneal hypersensitivity-induced conditions, such as marginal ulcers, and phlyctenulosis, even though they all involve staphylococcal antigen hypersensitivity. Marginal ulcers are typically oval in shape, are located at the 2, 4, 8 and 10 o'clock positions and run parallel to the limbus. Although the infiltrate is always separated by a clear interval, it can be spanned by blood vessels. In distinction, CLPUs can occur at any position in the peripheral cornea. There is no clear interval, as infiltrates are seen to stream from the limbal vasculature to the focal infiltrate, and there are no bridging vessels. CLPUs differ from corneal phlyctenules, as there is no raised nodular infiltrate or vascularization.

Reference: Corneal Infiltrative Complications Associated With Contact Lens Wear,
Tags: contact lens, CLPU, Extended wear,

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