白内障

title: 描述.
content: 白内障是种眼睛晶状体发生混浊的疾病,在中医学又称「圆翳内障」。白内障可致盲,其流行情况因地而异。一般来说,随着年龄的增长,白内障的发病率逐渐提高。  晶状体的混浊位置可以在皮质、核、前囊或者后囊等处。晶状体的混浊不一定影响视力。出现在视轴上的混浊对视力的影响较大,例如后囊下的混浊,由于其处于眼球这个光学系统的节点处,所以即使是较小的混浊也对视力有较大的影响。  典型的白内障的临床表现是视力渐进下降,由于晶状体的密度变化,还可能伴有近视度数加深,单眼复视(单眼看东西时出现多个物像)等症状。一般不伴有眼红眼痛。目前虽然有许多药物,但尚无药物可以使白内障的进程逆转。所以真正可以使患者视力恢复的治疗仍是手术治疗。  手术的目的是为了去除已经混浊的晶状体,并植入人工晶状体以提高患者的视力。以前由于手术技术的限制,皮质型白内障的手术需要到成熟期才可以进行,此时患者基本上已经没有视力。目前白内障手术的技术已经突破此限制,其适应症大大放宽。
title: 分类及成因.
content: 由于水晶体的化学成分改变而导致混浊,其中以老化所造成的老年性白内障最为常见。依不同类型的白内障造成原因如下:  症状主要症状为无痛无痒的进行性视力减退,会觉得有一层毛玻璃挡在眼前。其他症状包括,复视、畏光、眩光、色彩失去鲜明度,和经常需要更换眼镜等症状。水晶体也可能吸收水分而增厚,导致近视者度数加深,而老花眼者阅读书报反而不需戴眼镜,以为得到眼睛的「第二春」。当视力再也无法以更换眼镜度数来改善时,就到了必须积极治疗的时候。
title: 预防.
content: 医学文献表明,佩戴防紫外线光的墨镜有可能减慢白内障的发展。
title: 治疗方式.
content: 手术摘除是唯一有效的治疗。当白内障严重到影响个人的工作及日常生活,便是考虑接受白内障手术的时候了,不论视力是多少。  目前的白内障手术可概括分为两类,分别为白内障超声乳化术及囊外白内障摘除手术。囊外白内障摘除手术为较旧式的白内障手术。白内障超声乳化术则属现代化的二代白内障手术。  现代化的二代白内障手术分两步骤,第一步骤透过超音波晶体乳化术,以超音波把水晶体乳化后吸走,因为此步骤会留后囊。第二步骤,当后囊也出现混浊时在门诊直接做雅铬激光。二代白内障手术,是打开前囊保留后囊,来进行晶体乳化术,保留后囊可以使晶体乳化容易进行,也能够安全的放入人工水晶体。现在还有散光治疗型人工水晶体,能借由去除散光来加强改善患者术后视力,防蓝光人工水晶体则加强防护3C电子产品对黄斑部的损耗。  至于某些市售的白内障药水,这类眼药以心理治疗的层面较大,没有证据证明有效。
title: 如何在白内障手术后保持视力永久清晰.
content: 一般而言,软性可折叠式的人工水晶体在白内障手术植入眼内一段时间后,镜片内容易产生细小的香槟液泡(Glistening)的现象,影响视力品质。手术前可与医师讨论手术的风险,以及慎选适合或不会产生香槟液泡的人工水晶体。手术后按时点药与回诊检查。

Summary: 白内障()是因为眼睛水晶体混浊而造成视力缺损的疾病,可能侵犯单眼或双眼。症状包含彩度降低、视线模糊、光源产生光晕、无法适应亮光,以及黑暗环境下视觉障碍。白内障可能导致驾驶困难、阅读障碍,以及识人能力减低。视觉减退也会导致跌倒和忧郁的风险。该病为全球半数眼盲及33%视力受损病例的原因。 白内障最常见的原因为老化,其他原因则包含创伤、辐射线暴露、先天性、眼睛手术后的并发症,或是其他原因。风险因子包含糖尿病、吸烟、阳光暴露过久,以及酒精。造成白内障的原因为,沉积在水晶体的蛋白质团块或黄棕色色素导致水晶体的透明度减低,进而使视网膜能传感到的光线下降。诊断方式为视力测试。 预防方法包含配戴太阳眼镜及禁烟。症状初期可能可以借由配戴眼镜改善。若效果不佳,唯一有效的疗法为白内障手术,移除混浊的水晶体并换上人工水晶体,不过只有白内障影响到日常生活时才需要进行手术,一般而言,手术会提升生活品质。白内障手术在许多国家仍无法实施,尤其是女性、乡村居民,以及文盲等患者,特别少进行手术。 约全球约2000万人因白内障而眼盲,该病占美国盲眼人口病因的5%,在非洲及南美则接近六成。在发展中国家,儿童因白内障导致眼盲的发生率约为每十万人中10-40人,已开发国家则为每十万人1-4人。白内障的比例会随年龄提高,在美国80岁以上的老人有半数以上罹患此病。

Cataract: A cataract is an opacification of the lens of the eye which leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing faces. Poor vision caused by cataracts may also result in an increased risk of falling and depression. Cataracts cause half of all cases of blindness and 33% of visual impairment worldwide. Cataracts are most commonly due to aging but may also occur due to trauma or radiation exposure, be present from birth, or occur following eye surgery for other problems. Risk factors include diabetes, smoking tobacco, prolonged exposure to sunlight, and alcohol. The underlying mechanism involves accumulation of clumps of protein or yellow-brown pigment in the lens that reduces transmission of light to the retina at the back of the eye. Diagnosis is by an eye examination. Prevention includes wearing sunglasses, a wide brimmed hat, eating leafy vegetables and fruits, and avoiding smoking. Early on the symptoms may be improved with glasses. If this does not help, surgery to remove the cloudy lens and replace it with an artificial lens is the only effective treatment. Cataract surgery is not readily available in many countries, and surgery is needed only if the cataracts are causing problems and generally results in an improved quality of life. About 20 million people are blind due to cataracts. It is the cause of approximately 5% of blindness in the United States and nearly 60% of blindness in parts of Africa and South America. Blindness from cataracts occurs in about 10 to 40 per 100,000 children in the developing world, and 1 to 4 per 100,000 children in the developed world. Cataracts become more common with age. In the United States, cataracts occur in 68% of those over the age of 80 years. Additionally they are more common in women and White people.