Residential geography, time spent in the sun, and whether or not sunglasses are worn may help explain why some people develop exfoliation syndrome (XFS), an eye condition that is a leading cause of secondary open-angle glaucoma and can lead to an increased risk of cataract and cataract surgery complications, according to a study published on Sept. 4 in JAMA, Ophthalmology. Despite improvements in understanding the cause of this common yet life-altering condition, more work needs to be done. "The discovery that common genetic variants in the lysyl oxidase-like 1 gene (LOXL1) are associated with 99 percent of XFS cases represented a significant advance in our understanding of this condition," said the study's lead author, Louis Pasquale, M.D., Associate Professor of Ophthalmology at Harvard Medical School (HMS), and director of the HMS Glaucoma Center of Excellence and Mass. Eye and Ear Glaucoma Service and Telemedicine Service. "However, 80 percent of control individuals also harbor these variants and that ratio of cases to control individuals with trait-related variants is fairly similar in regions where XFS is very prevalent and in regions where the condition is relatively rare; this suggests that other genetic or environmental factors contribute to XFS."
Residential geography, time spent in the sun, and whether or not sunglasses are worn may help explain why some people develop exfoliation syndrome (XFS), an eye condition that is a leading cause of secondary open-angle glaucoma and can lead to an increased risk of cataract and cataract surgery complications, according to a study published on Sept. 4 in JAMA, Ophthalmology.
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Despite improvements in understanding the cause of this common yet life-altering condition, more work needs to be done. "The discovery that common genetic variants in the lysyl oxidase-like 1 gene (LOXL1) are associated with 99 percent of XFS cases represented a significant advance in our understanding of this condition," said the study's lead author, Louis Pasquale, M.D., Associate Professor of Ophthalmology at Harvard Medical School (HMS), and director of the HMS Glaucoma Center of Excellence and Mass. Eye and Ear Glaucoma Service and Telemedicine Service. "However, 80 percent of control individuals also harbor these variants and that ratio of cases to control individuals with trait-related variants is fairly similar in regions where XFS is very prevalent and in regions where the condition is relatively rare; this suggests that other genetic or environmental factors contribute to XFS."
Although previous studies have shown that residential (geographic) history and extent of solar exposure may be important risk factors for XFS, detailed lifetime solar exposure had not previously been evaluated. Researchers from Mass. Eye and Ear, Brigham and Women's Hospital, Harvard Medical School, Goldschleger Eye Institute, Chaim Sheba Medical Center, Tel Aviv University, Tel Hasomer Israel, Case Western Reserve University, and New York Eye and Ear Infirmary set out to assess the relationship between residential history, solar exposure and XFS in the study.
Researchers conducted a clinic-based, case-control study in the United States and Israel, involving XFS cases and control individuals (all 60 years or older, white individuals) enrolled from 2010 to 2012 (United States: 118 cases and 106 control participants; Israel: 67 cases and 72 control individuals) They measured weighted lifetime average latitude of residence and average number of hours per week spent outdoors as determined by validated questionnaires.
They found that each degree of weighted lifetime average residential latitude away from the equator was associated with an 11 percent increased odds of XFS.
Eye examination image via Shutterstock.
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