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(xué)文獻(xiàn)》（Archives of Ophthalmology）上,，一項(xiàng)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(fēng)險(xiǎn)較低。
老年黃斑病變（AMD）產(chǎn)生原因是黃斑隨著時(shí)間發(fā)生退化,，黃斑是視網(wǎng)膜后端產(chǎn)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(xiàng)稱為“年齡相關(guān)眼病研究”的項(xiàng)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(duì)參與者視網(wǎng)膜進(jìn)行拍照以確定其是否患有AMD,，如果有,，則需進(jìn)一步確定發(fā)展到疾病發(fā)展4個(gè)階段中的哪一個(gè)階段。參與者同時(shí)還需要完成一份針對(duì)食物的調(diào)查問卷,，以評(píng)估其攝入富含某些維生素,、礦物質(zhì)和營(yíng)養(yǎng)素的食物情況。這些被調(diào)查物質(zhì)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(yíng)養(yǎng)素的情況被分成5組,。結(jié)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(shí)這些參與者患玻璃體疣、視網(wǎng)膜黃白沉積和其它AMD標(biāo)志性疾病的幾率也更低,。除此之外未觀測(cè)到其它營(yíng)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(zhǎng)光線，短波長(zhǎng)光不但會(huì)造成光化學(xué)損傷,，而且會(huì)產(chǎn)生攻擊細(xì)胞脂類,、蛋白和核物質(zhì)的活性氧分子。此外,，類胡蘿卜素還能減少新產(chǎn)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(jī)制尚未完全明確，尚無(wú)非常有效的治療方法,。近年來(lái)在發(fā)病機(jī)制,、遺傳因素、危險(xiǎn)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(jīng)驗(yàn)，取得了一定的療效,，有其獨(dú)特的優(yōu)勢(shì),，值得進(jìn)一步研究。
老年黃斑病變,，隨年齡增長(zhǎng)發(fā)病率和患病率不斷增高,，是目前國(guó)內(nèi)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(xiǎn)因素有關(guān),。
由于黃斑點(diǎn)退化,，引致患者的中央視覺受損。黃斑點(diǎn)位于視網(wǎng)膜的中央部位,，具備精細(xì)視物功能,。黃斑點(diǎn)有大量的感光細(xì)胞，把影像轉(zhuǎn)換成電流脈沖,，然后通過視神經(jīng)傳送到大腦,。老年黃斑病變患者之所以視力受損，就是因?yàn)辄S斑點(diǎn)的感光細(xì)胞退化,。
老年黃斑病變的病人首先會(huì)感到視覺中央有些模糊,，在閱讀、做針線時(shí)尤為明顯,，看直線時(shí)會(huì)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(diǎn),。大部份案例顯示,，如果其中一只眼患上這種眼疾時(shí)，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.
