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04-01-2012 | General practice | Article

Pterygium 'may be preventable with eye UV protection'


Free abstract

MedWire News: Pterygium occurs in one-tenth of Norfolk Islanders in the South Pacific and is associated with ocular ultraviolet radiation (UVR), report Australian researchers who recommend eye protection to reduce the prevalence of pterygium in the community.

Although the pathology of pterygium, which is characterized by, among others, inflammation, neovascularization, and fibrosis, is typically benign, ocular surface squamous neoplasia is identified in approximately 10% of patients. UVR is known to be linked to pterygium, but the mechanism is multifactorial and not clearly understood.

To determine the association between a biomarker of UVR and pterygium, David Mackey, from the University of Western Australia, in Nedlands, and colleagues studied 641 permanent residents, aged 15 years or older, of Norfolk Island in the South Pacific who completed a sun-exposure questionnaire and underwent autorefraction and slit lamp biomicroscope examination.

The team also calculated the conjunctival ultraviolet autofluorescence (UVAF) in the right and left eyes, and used logistic regression analysis to examine the association between UVAF and pterygia.

The results, published in the journal Acta Ophthalmologica, reveal that 70 people had pterygia in 99 eyes, giving a prevalence of pterygium in one or both eyes of 10.0%. There was no association between age and pterygium, but the prevalence of pterygium was almost twice as high in males as in females, at 15.0% versus 7.7% in one or both eyes.

Multivariate analysis indicated that increasing conjunctival UVAF, spending more than 75% of the day outdoors, and a skin phenotype that tans were also independent risk factors for pterygium, at odds ratios of 1.16, 2.22, and 2.17, respectively. It was also found that increasing quartiles of UVAF were significantly associated with the prevalence of pterygium, at odds ratios of 2.62 and 3.64 for the third and fourth quartiles, respectively, compared with the first quartile.

In addition, the researchers discovered that UVAF was significantly associated with age, gender, tanning skin type, and spending over 75% of the day outdoors. A model incorporating these variables explained 15% of the variance in UVAF.

They conclude: "Using conjunctival UVAF as a surrogate for ocular UVR exposure, we have demonstrated that conjunctival UVAF is associated with the presence of pterygia, confirming earlier epidemiological, histopathological and ray-tracing studies.

"In addition, we have shown that outdoor activity is associated with the degree of UVAF. Protection from the sun should be encouraged to reduce the prevalence of pterygium in the community."

By Liam Davenport

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