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【medical-news】美国《眼科学》2008年5月号期刊重量
Three studies in the May 2008 issue of Ophthalmology, the journal of the American Academy of Ophthalmology, shed new light on important eye health issues: the role of antioxidant supplements, the relationship of visual acuity and mortality, and the complex causes of glaucoma.
Vitamin E May Offer Women No Protection from Cataract
A new analysis of the Women's Health Study (WHS) found that women who took Vitamin E supplements had rates of cataract development comparable to women who did not take such supplements. Dr. William G. Christen and colleagues used data from the landmark WHS, in which 39,876 professional women aged 45 or older took 600 IU of vitamin E (every other day) and 100 mg of aspirin (every day) in this 10-year, randomized, controlled study on cardiovascular disease and cancer prevention. Each woman's cataract history was also recorded, along with health and lifestyle factors such as history of cigarette smoking, alcohol consumption and use of multivitamins.
Dr. Christen said his study's findings are consistent with four previous randomized trials: "Together, these results indicate that supplementation with vitamin E, alone or in combination with other antioxidant nutrients, for durations as long as 6.5 years has little impact on cataract occurrence in well-nourished patients." The results held for women who might have been expected to benefit most from antioxidant supplements: smokers and those with hypertension and/or diabetes. But since age-related cataract develops over many years as a result of cumulative damage to the eye's lens, longer timeframes might be necessary to see a benefit from antioxidant supplements, Dr. Christen said.
Sharp Vision Linked to Longer Life in Initial Asian Population Study
In the first study of its type in an Asian population, researchers found that the relationship of age and cause of death to visual acuity - the ability to see objects clearly and in detail--was consistent with results of similar studies in Western countries. Dr. Tien Yin Wong led the study of 1,232 Chinese people who lived in Singapore, a major urban center. About 10 percent of the subjects died during the 1998 to 2004 study period.
Analysis of the subjects' health and, when appropriate, death records showed that the death rate was significantly increased---three times higher---for those whose vision measured 20/40 or worse, after the data were adjusted for age, gender, hypertension, diabetes, smoking, heart attack, and stroke. Cause of death differed among VA categories; for example, cancer was the leading cause in people with normal vision. The researchers speculated that compromised vision could have contributed to fatal falls and accidents and reduced other quality of life and health factors that impact mortality.
Related studies have hypothesized that lens changes that occur in cataract might reflect cellular processes associated with aging and the acceleration of the dying process, but Dr. Wong said their study did not find specific links between cataract, glaucoma, or a number of other eye disorders and mortality.
Is Cerebrospinal Fluid Pressure Related to Glaucoma?
New evidence is emerging that low cerebrospinal fluid pressure may be a significant contributor to optic nerve damage in glaucoma, the complex eye disorder that affects more than 2.2 million Americans over age 40. Cerebrospinal fluid (CSF), the fluid that surrounds the brain and the spinal cord, also surrounds the optic nerve and helps maintain appropriate pressure on the optic disc. All forms of glaucoma damage the disc of the eye's optic nerve, compromise the transmission of images to the brain, and eventually result in blindness if untreated. Intraocular pressure, IOP, is a key measurement taken by eye specialists when screening people for glaucoma, but abnormal IOP is now considered just one of several factors that play a role. Glaucoma researchers are increasingly interested in how the interaction of IOP and CSF pressure, termed the translaminar pressure difference, affects the optic nerve disc.
John Palmer Berdahl, MD, and his team compared the medical records of 28 patients who had primary open-angle glaucoma, POAG, with 49 control group patients who did not have glaucoma; all had been examined by an ophthalmologist (Eye MD). Subjects were selected from a records review of 31,786 patients who had CSF samples taken by lumbar puncture between 1996 and 2007 at the Mayo Clinic, Rochester, MN. Open-angle glaucoma was studied because it is the most common form of the disorder. CSF pressure was found to be significantly lower in all POAG patients than in the controls, independent of the health reasons that prompted the lumbar puncture or the patient's age.
"Other types of glaucoma and populations should now be studied to improve our understanding of the role that translaminar pressure difference plays in the pathogenesis of glaucoma," Dr. Berdahl said.
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作者:admin@医学,生命科学 2010-12-09 17:11
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