老年黃斑病變（age - related macular degeneration,，AMD）是目前全球主要致盲性眼病之一,，發(fā)病率不斷增加。在9月的《眼科學文獻》（Archives of Ophthalmology）上,，一項研究顯示攝入較多的黃色植物色素——葉黃素和玉米黃素的人,，患老年黃斑病變的風險較低,。
老年黃斑病變（AMD）產生原因是黃斑隨著時間發(fā)生退化，黃斑是視網膜后端產生視覺的區(qū)域,。文章表示,，AMD是造成歐洲老年人群失明的主要原因。
這項稱為“年齡相關眼病研究”的項目,，在1992到1998年間分析了4519位年齡在60－80歲之間的人,。研究中，研究人員對參與者視網膜進行拍照以確定其是否患有AMD,，如果有,，則需進一步確定發(fā)展到疾病發(fā)展4個階段中的哪一個階段,。參與者同時還需要完成一份針對食物的調查問卷,，以評估其攝入富含某些維生素、礦物質和營養(yǎng)素的食物情況,。這些被調查物質包括葉黃素,、玉米黃素、胡蘿卜素,、番茄紅素,、維生素C和E。
參與者根據(jù)攝入每種營養(yǎng)素的情況被分成5組,。結果食用葉黃素和玉米黃素最多的小組患AMD的比例明顯較低,。同時這些參與者患玻璃體疣、視網膜黃白沉積和其它AMD標志性疾病的幾率也更低,。除此之外未觀測到其它營養(yǎng)素和這些癥狀間存在聯(lián)系,。
葉黃素和玉米黃素也被稱為類胡蘿卜素，它們存在于黃色和暗色葉片蔬菜中,。類胡蘿卜素能阻止光和氧氣破壞眼睛的過程,。葉黃素和玉米黃素能濾掉短波長光線，短波長光不但會造成光化學損傷,，而且會產生攻擊細胞脂類,、蛋白和核物質的活性氧分子。此外,，類胡蘿卜素還能減少新產生的活性氧,。
老年黃斑病變（age - related macular degeneration，AMD）是目前全球主要致盲性眼病之一,，發(fā)病率不斷增加,。其病因和發(fā)病機制尚未完全明確，尚無非常有效的治療方法,。近年來在發(fā)病機制,、遺傳因素,、危險因素等方面又有了新的研究，治療手段也有增加,，但也存在很多問題,。中醫(yī)中藥在治療AMD方面積累了很多經驗，取得了一定的療效,，有其獨特的優(yōu)勢,，值得進一步研究。
老年黃斑病變,，隨年齡增長發(fā)病率和患病率不斷增高,，是目前國內外50歲以上人群低視力和致盲的重要原因。其病因不清,，可能與慢性光損害,、種族、遺傳,、吸煙,、心血管疾病、飲食等危險因素有關,。
由于黃斑點退化,，引致患者的中央視覺受損。黃斑點位于視網膜的中央部位,，具備精細視物功能,。黃斑點有大量的感光細胞，把影像轉換成電流脈沖,，然后通過視神經傳送到大腦,。老年黃斑病變患者之所以視力受損，就是因為黃斑點的感光細胞退化,。
老年黃斑病變的病人首先會感到視覺中央有些模糊,，在閱讀、做針線時尤為明顯,，看直線時會出現(xiàn)變形彎曲,。隨著病情發(fā)展，在視覺中央逐漸形成盲點,。大部份案例顯示,，如果其中一只眼患上這種眼疾時，另一只眼也很可能得病,。
原始出處:
Archives of Ophthalmology
Vol. 125 No. 9, September 2007
Age-Related Macular Degeneration and Cancer Mortality in the Atherosclerosis Risk in Communities Study
Ning Cheung, MBBS; Anoop Shankar, MD, MPH; Ronald Klein, MD, MPH; Aaron R. Folsom, MD, MPH; David J. Couper, PhD; Tien Yin Wong, MD, PhD; for the Atherosclerosis Risk in Communities (ARIC) Study Investigators
Arch Ophthalmol. 2007;125:1241-1247.
Objective To examine the prospective association of early age-related macular degeneration (AMD) with cancer mortality.
Methods A population-based cohort study of 10 029 persons aged 49 to 73 years free of cancer. The AMD signs were evaluated from retinal photographs taken in 1993 through 1995. Cancer mortality was determined from death records.
Results There were 464 cases of early AMD. Over 10 years, there were 234 cancer deaths (71 lung cancer deaths). After controlling for age, sex, race, field center, education, smoking status, pack-years of smoking, body mass index (calculated as weight in kilograms divided by height in meters squared), and diabetes mellitus, early AMD was associated with cancer mortality (rate ratio [RR], 1.68; 95% confidence interval [CI], 1.03-2.73). This association was overall stronger in African American individuals (RR, 3.93; 95% CI, 1.67-9.22) than white individuals (RR, 1.28; 95% CI, 0.71-2.32) and for lung cancer deaths (RR, 2.14; 95% CI, 0.97-4.72) than nonlung cancer deaths (RR, 1.50; 95% CI, 0.81-2.78). In African American individuals, early AMD was associated with a 5-fold higher risk of lung cancer deaths (RR, 5.28; 95% CI, 1.52-18.40).
Conclusions Middle-aged African American individuals with early AMD may be at increased risk of dying of cancer, particularly lung cancer. This association was not present in white individuals and needs confirmation in other studies.
Author Affiliations: Centre for Eye Research Australia, University of Melbourne (Drs Cheung and Wong), and Royal Melbourne Hospital (Dr Cheung), Victoria; Department of Community, Occupational, and Family Medicine, Yong Loo Lin School of Medicine (Dr Shankar), and Singapore Eye Research Institute (Dr Wong), National University of Singapore; Department of Ophthalmology, University of Wisconsin, Madison (Dr Klein); Division of Epidemiology and Community Health, University of Minnesota, Minneapolis (Dr Folsom); and Department of Biostatistics, University of North Carolina, Chapel Hill (Dr Couper).
Group Information: A list of the ARIC Study investigators was published in Am J Epidemiol. 1989;129:687-701.
