Keratitis - Can You Get The Diagnosis Correct?
BY JOSEPH T. BARR, OD, MS, FAAO, EDITOR
Corneal infection and inflammation was a discussion topic at the December 2002 American Academy of Optometry meeting in San Diego. H. Dwight Cavanagh, MD, PhD, FAAO, Peter Zloty, MD, and Christopher Snyder, OD, MS, FAAO, were the featured speakers, and Joe Molinari, OD, MEd, FAAO, and I moderated the program. Among other things, the speakers discussed culturing a presumed infectious keratitis and the importance of culturing the lens case as well as the eye. Although hydrogel soft lens extended wear induces an infected corneal ulcer in 0.2 percent of patients, silicone hydrogels may cause this feared microbial keratitis in only one in 0.00005 percent of cases, though this latter number could change with better tracking and time. Previous inflammation, exposure to smoke, swimming and being a young male may increase a patient's susceptibility to a serious infection. Certainly, do not tell patients with prewear moderate to severe dry eye, meibomian gland dysfunction or other risk factors to sleep while wearing their lenses.
The Cornea and Contact Lens Research Unit at the University of New South Wales, Australia, in cooperation with the LV Prasad Eye Institute in Hyderabad, India, have established a thorough and well documented corneal infiltrative condition guideline that outlines the differential diagnosis of MK, contact lens-induced peripheral ulcer (CLPU), contact lens-induced acute red eye (CLARE), infiltrative keratitis (IK), classic viral keratoconjunctivitis, superior epithelial arcuate lesions (SEALs), asymptomatic infiltrative keratitis (AIK) and asymptomatic infiltrates (AI). It behooves all who examine contact lens wearers to make sure our differential diagnosis is rational. We should at least consider the classic traumatic, toxic, allergic and microbial causes. Also, we need to be sure of the location, size and probable cause of a corneal lesion. Central 6mm, larger than 1mm infiltrates that stain, and associated severe pain, photophobia, anterior chamber reaction and intense injection, raise our concern of MK, especially if signs and symptoms are steady or worsening.
Experienced researchers and clinicians outside the United States often will not treat most of these lens-related inflammations with antibiotics in the absence of a presumed microbial keratitis. Certainly, no steroids (or patching of lens-related abrasions) are warranted until any infection is well under control in most cases. U.S. practitioners prefer to treat any possibly infectious keratitis with antibiotics until proven unnecessary.
Some industry experts fear that non-significant complications will be reported as serious conditions, and the number of ulcers will be inflated. We need to make sure we do not consider a significant event nonsignificant and withhold treatment. If you encounter a severe reaction with a contact lens, make sure you report it to us, to the manufacturer or to the FDA via e-mail at firstname.lastname@example.org.