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Time spent outdoors associated with increased risk for exfoliation syndrome
Study showed that each degree of average residential latitude away from the equator was associated with 11% increased odds of exfoliation syndrome.
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Ocular exposure to sunlight and greater exposure at a young age may be key risk factors for exfoliation syndrome, exfoliation glaucoma or exfoliation glaucoma suspect, according to two studies.
One study focused on the relationship between geographic location and time spent outdoors and the risk of exfoliation syndrome. The other study examined an association between time spent outdoors at various ages and the risk of exfoliation glaucoma or exfoliation glaucoma suspect.
The exfoliation syndrome study was conducted in the U.S. and Israel. The exfoliation glaucoma study was conducted in the U.S.
“Both studies demonstrate that more time spent outdoors was associated with increased risk of exfoliation syndrome/glaucoma,” Louis R. Pasquale, MD, an investigator in both studies, told Ocular Surgery News. “The anterior uveal tract is a critical site of injury in [exfoliation syndrome]. We believe that anterior uveal tract exposure from reflected solar rays damages the iris vessels in genetically predisposed individuals and contributes to the formation of exfoliation material.”
The exfoliation syndrome study was published in JAMA Ophthalmology. The exfoliation glaucoma study was published in American Journal of Ophthalmology.
Exfoliation syndrome
The exfoliation syndrome study included, in the U.S., 118 subjects with exfoliation syndrome and 106 controls and, in Israel, 67 subjects with exfoliation syndrome and 72 controls. All subjects were white and older than 60 years.
The investigators evaluated geographic location, duration of sunlight exposure and the use of protective items such as sunglasses, hats and visors.
Each degree of average residential latitude away from the equator was associated with 11% increased odds of exfoliation syndrome; this finding was statistically significant (P < .001).
“People whose lifetime-weighted geographic residence was farther from the equator were at increased risk of exfoliation syndrome. This is now the third study to show a positive association between increasing latitude and risk of [exfoliation syndrome],” Pasquale said.
Every hour weekly spent outdoors during the summer over a lifetime correlated with 4% increased odds of exfoliation syndrome.
For every 1% of average time spent in sunlight between 10 a.m. and 4 p.m. in the summer, the odds of exfoliation syndrome decreased by 2% when sunglasses were worn in the U.S. but not in Israel.
After accounting for environmental factors in the U.S., history of work over water or snow correlated with increased odds of exfoliation syndrome. In Israel, there was an insufficient number of subjects for such an analysis.
Brimmed hat wear had no association with exfoliation syndrome.
Exfoliation glaucoma or suspect
The retrospective exfoliation glaucoma study included 49,033 women and 20,066 men older than 60 years without glaucoma or cataract who completed a questionnaire about time spent outdoors in direct sunlight at mid-day at three life periods: high school to age 24 years, 25 to 36 years and 36 to 59 years. Medical records were used to confirm 223 women and 33 men with incident exfoliation glaucoma or exfoliation glaucoma suspect.
There was no association with greater time spent outdoors between the ages of 25 and 35 years or 36 and 59 years. However, pooled multivariable-adjusted rate ratios for 11 hours or more per week spent outdoors in high school to age 24 years compared with less than 5 hours per week was 2.00, a significant difference (P = .001). – by Matt Hasson
References:
Kang JR, et al. Am J Ophthalmol. 2014;doi:10.1016/j.ajo.2014.05.015.Pasquale LR, et al. JAMA Ophthalmol. 2014;doi:10.1001/jamaophthalmol.2014.3326.
For more information:
Louis R. Pasquale, MD, can be reached at Glaucoma Service, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA 02114; email: louis_pasquale@meei.harvard.edu.Disclosure: Pasquale has no relevant financial disclosures.