認識白內障(1)

(1) 什麼是白內障

眼球晶體是位於虹膜與玻璃體之間，在正常的情況下，晶體是透明的，當光線透過角膜後，須經晶體的拆射，才能將影像清晰地呈現在視綱膜上，就好像照相機的鏡頭一般，使光線聚焦在底片一樣。白內障是一種常見的眼疾，即透明的晶體變得混濁時，會令觀看的事物模糊不清，便是白內障。

(2) 白內障的成因

白內障的主因是眼球晶體隨著年齡的增長而老化。除此之外，糖尿病、眼外傷、眼內炎、藥物的副作用和先天性因素等亦會引致白內障。

(3) 老年性白內障

為最常見的一種白內障，隨著年齡的增加，當成年人達至四、五十歲以後，眼球晶體便會慢慢發生硬化、混濁等情況，漸而造成視力的障礙。

據統計資料顯示，白內障的罹患率，六十歲以上人士約有50%，七十歲以上人士則高達70%，所以，對於長者來說，老年性白內障可以說是普遍的疾病。根據美國的資料顯示，每年至少有四十萬以上的病人，因患上白內障而需要接受手術。

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的眼科醫生查詢，而不應單倚賴以上提供的資料。

Amblyopia and Your Child's Eyes (continued...)

How Is Amblyopia Treated?

The most common treatment for amblyopia is to force the brain to start using the "bad" eye by putting a patch over the "good" eye. At first, the child will have a hard time seeing with just the weaker eye. However, it is very important that your child wear the patch diligently because this will eventually improve vision. It can take weeks or months for an eye patch to improve vision.

As the child keeps using only the eye with amblyopia, his or her vision will continue to improve. After the doctor determines that vision is back to normal, your child will not have to wear the patch. Some children may again lose some vision and need to undergo another round of patching. In cases of mild amblyopia, the doctor might recommend using an eye drop called atropine in the "good" eye instead of a patch. Atropine blurs the vision in the "good eye," forcing the "bad" eye to do most of the work while the child is playing with toys, eating, drawing, or reading.

Most children with amblyopia will also need glasses to help focus. If there is something blocking light from getting into the eye, the doctor might recommend surgery to remove the blockage. If strabismus is preventing the eyes from moving together correctly, your doctor might recommend surgery on the muscles of the eye. Your doctor will discuss with you what treatment is most appropriate for your child.

What Is the Outlook for Children With Amblyopia?

If existing underlying problems are treated and the amblyopia is detected and treated early, most children will gain vision. Because amblyopia becomes much more difficult to treat after about 7-9 years of age, early childhood exams are very important. It is important that you follow your doctor's advice about treatment. This can be very difficult, because many children do not want to wear an eye patch every day. With the use of atropine as an alternative method of treatment, success is now possible in a larger proportion of children with amblyopia.

Reference information: http://www.webmd.com

It is not intended as medical advice to any specific person. If you have any need for personal advice or have any questions regarding your health, please consult your Ophthalmologist for diagnosis and treatment.

Amblyopia and Your Child's Eyes

Amblyopia is a condition that occurs in children when vision has not developed properly in each eye. If amblyopia is left untreated, a child's vision will not develop correctly. The child's brain, as it matures, will start "ignoring" the image coming from the bad eye. This causes vision in the affected eye to become poor. Because amblyopia can result in permanent vision loss in one eye, it is important to have a child with amblyopia regularly tested by an eye doctor.

What Causes Amblyopia?

Amblyopia usually starts when one eye has much better focus than the other eye. For example, one eye might be very nearsighted or have a lot of astigmatism, while the other does not. When the child's brain is confronted with both a blurry image and a clear image, it will begin to ignore the blurry image. If this goes on for months or years, the vision in the eye that sees the blurry image will deteriorate.

Another cause of amblyopia is strabismus. Strabismus is an ocular misalignment, meaning that one eye turns inward or outward. This prevents the eyes from focusing together on an image and can cause double vision. In order to combat this, the child's brain generally chooses to ignore the image from the deviated eye, causing the vision in that eye to deteriorate. Because one of the eyes is misaligned, some people refer to this as a "lazy eye."

Other children cannot see well in one eye because something blocks light from getting through. This could be due, among other causes, to a cataract or a small amount of blood or other material in the back of the eye.

How Is Amblyopia Diagnosed?

All children should be screened before they are school age. Your child's doctor or the vision program at school will check three aspects of your child's eye health:

s   That your child's eyes let light all the way through.

s   That both eyes see equally well.

s   That the eyes are moving normally.

If there's a problem in any of those three areas, the doctor or school nurse may recommend a visit to an eye specialist. If you feel that something could be wrong with your child's vision, call your doctor even if he or she has been screened at school.

Family history of amblyopia is a risk factor for amblyopia. Parents cannot tell just by looking at their child if they have amblyopia. Early diagnosis and treatment are the keys to the best visual outcome.

Reference information: http://www.webmd.com

It is not intended as medical advice to any specific person. If you have any need for personal advice or have any questions regarding your health, please consult your Ophthalmologist for diagnosis and treatment.

眼科

一種名為Argon Laser 的激光治療，是預防視網膜脫落的唯一方法。這種激光做法簡單，每隻眼睛大約需時十分鐘，病人坐在激光儀器前,滴了麻醉眼水後，便把一個激光鏡放在眼球上，引導激光通過角膜、晶體及玻璃體，直達視網膜，令激光在視網膜上產生類似發炎的效果；三星期後，那些接受過激光治療視網膜退化的地方及小洞的周圍將會穩固下來，防止視網膜繼續惡化。

接受Argon Laser 激光治療後，漂浮物及閃光的情況或會繼續出現，因為仍有退化及小洞存在，不過情況已受控制，不會惡化不去而變成視網膜脫落。病人須每年定期接受檢查，確保視網膜其他未接受激光治療的部位沒有出現退化問題。

視網膜脫落的病徵同樣會出現飛蚊或閃光，它們突然大量增多，視力也開始受影響，如像銀幕慢慢垂下來，漸漸看不見東西，造成失明的時間由幾天至幾星期不等，視乎脫落的速度。Argon Laser 激光治療只可用在未脫落的視網膜上，如果已經脫落，就只有動手術，把穿孔用海綿體封閉，撫平視網膜。視網膜脫落的復原時間漫長，有些個案長達半年或一年，如果黃斑點也脫落了，視力會大不如前。如果脫落的時間太長，視網膜收縮了，手術可能不成功，最終不幸失明。

任何近視病人，無論有沒有病徵，都應該定期到眼科醫生進行擴瞳檢查視網膜，診斷視網膜的情況。眼科醫生便可以根據病人的情況，作出診治或定出將來需要檢查的頻密程度。須知道病徵輕微或普遍，並不反映病情的嚴重性。

參考資料: 《長者護眼常識100分》

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的眼科醫生查詢，而不應單倚賴以上提供的資料。

視網膜退化的訊號

一般來說，視網膜退化的徵狀輕微，甚至可沒有徵狀。較為敏感的病人，或會留意到眼睛出現漂浮物及閃光。漂浮物的成因，是由於眼睛裡透明玻璃體一些蛋白質與視網膜一起退化，變成不透明的物體；這些在視網膜上出現的影子，有點像蚊子在眼前飛來飛去，所以稱之為飛蚊症。至於閃光，有點像聖誕小燈泡的閃光，通常在走進黑暗環境時，或睡前關燈那一刻才注意到。

這是視網膜退化的訊號。視網膜細胞是感光細胞，所以只會發出閃光訊號，退化的視網膜細胞便會發出不必要的訊號，正如問題肌肉細胞不受控制地自己跳動抽搐起來，退化中的視網膜不會有痛的感覺，就算穿孔及發展至視網膜完全脫落，也不會感到痛楚。

視網膜出現小洞，可以與退化的情況一樣，難以察覺徵狀，同樣不會感到痛楚，最多是出現多了漂浮物及閃光。所以，如果發現有此問題，便應立刻找眼科醫生檢查，或是好定期每年接受檢查。

參考資料: 《21世紀近視療法話您知》

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的眼科醫生查詢，而不應單倚賴以上提供的資料。

近視引致的疾病

視網膜退化及視網膜脫落

近視患者的眼睛後部拉長，致使視網膜及其血管被拉緊變薄，因此，近視患者，特別是深近視患者，容易罹患視網膜退化，而退化的地方主要是視網膜周邊，那位置是視網膜最薄的部位。

退化發展下去，會出現小孔，當不斷有液體流進時，便會令視網膜逐漸脫落。

當視網膜脫落後，營養便不能傳送至視網膜外層的光感細胞，細胞逐漸死亡，最終會導致失明。須知視網膜細胞屬腦類細胞，不可以繁殖，死去的視網膜細胞不能由其他未脫落的正常細胞繁殖代替。

因為，視網膜一旦脫落，必須立刻進行緊急手術，把脫落了的視網膜放回原位。但手術效果是否理想，須視乎視網膜脫落的時間有多久，範圍有多大和壞死的細胞有多少而定。因此，大家必須盡力防範視網膜脫落。

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的眼科醫生查詢，而不應單倚賴以上提供的資料。

激光矯視儀器(3)

不要期望激光矯視手術後可變成零度近視，這幾乎是沒可能的，因為沒有人的眼睛是完美的。眼科醫生可在電腦輸入要求的近視度數，但最後角膜傷口癒合的情況如何，是無法百分之一百預測得到。

當角膜手術一個月後痊癒，往往會出現約百分之十的還原，即是說，如果手術前有五百度近視，手術後即使度數是零，但一個月後很大機會出現五十度近視；之後，度數將一直保持而不會再增加。

對於原本有一千度近視的病人來說，激光矯視手術後仍有一百度或更多一點的度數，結果也許並不算理想。為此，有時眼科醫生便要把目標度數增加，一千度近視以一千零五十度或一千一百度計，這樣病人手術後便有五十度或一百度遠視，當角膜傷口癒合時近視度數會還原一百度，換言之，最後近視度數理論上將會是五十度或零度了。當然，在這傷口癒合的一個月內會有遠視，看近距離的物體時會有困難，又或者近視還原少於一百度，日後則會有少許遠視。如果病人是二十至三十歲的青年，問題不大，但年屆四十或以上的病者，則會增加老花，進行近距離視力工作時出現困難，所以要特別留心眼科醫生事前向病人的講解。

又如果病人同時矯正散光，情況便變得有點複雜。眼科醫生會同時考慮病人的年齡和職業，以及其度數後才作出判斷。在決定病人需要同時矯正近視及散光時，眼科醫生的經驗具關鍵性，能對結果估計得更加準確，令病人滿意。

參考資料: http://www.eye123.com.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的眼科醫生查詢，而不應單倚賴以上提供的資料。