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PATIENTS infected with the human immunodeficiency virus (HIV) infection appear to be at increased risk of developing corneal ulcer, suggests a hospital-based cross-sectional study conducted in California. San Francisco ophthalmologist Bennie H Jeng MD presented the results of the new survey of corneal ulceration cases in the general population at the annual meeting of the Association for Research in Vision and Ophthalmology. Dr Jeng and his associates used the resources of the Kaiser Permanente Health Care System, which covers fully one-third of the population of Northern California, giving a very good sample of a diverse, relatively stable population which includes a wide range of socio-economic, as well as geographic, areas. Kaiser Permanente’s computer coding system made it possible to identify those patients in a population base of 1,093,210 who have been diagnosed with corneal ulcers during a one-year study period between September 1st, 1998 and August 31st, 1999. "Through a review of 468 charts of identified corneal ulcer cases in the computer system, we found 302 true corneal ulcers that met the inclusion criteria, which we define as an ulceration of the corneal epithelium with underlying stromal infiltration or inflammation caused by bacteria, fungus or parasites. The remaining 166 cases did not fit our definition and were excluded," Dr Jeng said. The study population consisted of 129 males and 173 females, with a mean age of 42.8 years. The highest rate of corneal ulceration was found in males over 85, with an incidence of 122.4 per 100,000 person-years. It was also high among females between 25 and 34 years, with an incidence of 60.3 per 100,000 person-years. The lowest rate of corneal ulceration was found in males less than 15-years-old, with an incidence of 0.9 per 100,000 person-years. Dr Jeng and his associates also looked at risk factors and found that contact lens wear was the greatest cause of corneal ulceration, comprising 55% of corneal ulcers in the United States, with an incidence of 121.6 cases per 100,000 person years, yielding a relative risk of 8.55 of having a corneal ulcer in contact lens wearers. Other risk factors include ocular surface disease (16.6%), trauma (11.9%), and bullous keratopathy (1.3%). Dr Jeng also disclosed a new finding that has never been published before - that HIV is a risk factor for developing corneal ulceration. For some reason, persons infected with HIV seem to be more predisposed to having corneal ulceration. Even though there have been case reports of spontaneous corneal infections in HIV-infected individuals, it has been generally believed that HIV infection alone does not predispose to bacterial corneal ulcers. In these previous reports, no attempts have been made previously to calculate the incidence to see if there is a higher risk. The Kaiser chart review found that seven of 2,944 known HIV-infected people (five of whom were contact lens wearers) developed corneal ulcers, yielding an incidence of 237.8 per 100,000 person-years for corneal ulceration in HIV-infected patients. The relative risk for corneal ulceration was 8.8 in HIV-infected individuals, compared to non-HIV-infected individuals. "Although our sample size is small, if we exclude contact lens wear as a risk factor, we have calculated a minimum incidence for corneal ulceration in HIV infected individuals of 67.9 per 100,000 person-years, with a relative risk of 4.78. "This increased risk may be due to additional factors, such as underlying immunodeficiency, HIV-associated keratoconjunctivitis sicca and anatomical lid abnormalities secondary to Kaposi's sarcoma and molluscum contagiousum, which may predispose to colonisation of the corneal surface by bacteria in individuals with HIV infection and ultimately impair the defense mechanism of the cornea. This calculation of the increased risk has never been shown before," Dr Jeng said. His message to clinicians is to be aware of the fact that contact lens wear is the greatest risk factor for developing corneal ulcers. Based on this study, he believes corneal ulceration occurs much more frequently than it was suggested in the past. In addition, clinicians should realise that the HIV positive patients they see in their clinics are at higher risk of developing corneal ulceration. Dr Jeng’s analysis shows an incidence value of 27.6 per 100,000 person years, which allows for an estimation of 75,200 corneal ulcers annually in the US, a figure that is higher than previously reported. This suggests that corneal ulcers are an even bigger public health problem than was believed previously. Earlier estimates of corneal ulceration showed that the incidence was approximately 11 per 100,000 person years, yielding somewhere between 27,000 and 30,000 cases in the US annually. University of California San Francisco, San Francisco, US Email: bjen8351@itsa.ucsf.edu
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