Glaucoma青光眼

advanced optic nerve damage by glaucoma

normal fundus and optic nerve

What is glaucoma?

Glaucoma is a disease that can damage the eye's optic nerve and result in vision loss and blindness. Glaucoma occurs when the normal fluid pressure inside the eyes slowly rises and damages the optic nerve fibres.

Glaucoma is the leading cause of blindness in Hong Kong (23%).

What are the types of glaucoma?

1. open-angle glaucoma (chronic)
   
2. angle-closure glaucoma (acute or chronic)
   
3. glaucoma secondary to injury, inflammation etc.
   
4. congenital glaucoma
   

Chronic Open-angle glaucoma is a common form of glaucoma. Reduced drainage of fluid through a spongy meshwork at the chamber angle is to blame for the slow rise in eyeball pressure that damages the optic nerve. It develops slowly, without obvious symptoms.

Angle closure glaucoma is caused by the reduced drainage through the narrow drainage angle between the cornea and iris, causing a rise in eyeball pressure. This can be acute or chronic. The acute form is marked by sudden, severe pain in the eye and sharply dropped vision, headache, red eyes and nausea. It occurs when there is a sudden sharp rise in eyeball pressure within a short time. The chronic form is caused by the acute form or secondary to other causes.

The following information points mainly to chronic glaucoma.

What are the types of glaucoma?

Anyone can develop glaucoma. Some people are at higher risk than others. They include:

• Everyone over age 60
• People with a family history of glaucoma.
• People with diabetes
• People with high myopia, uveitis, and those using steroid eyedrops

What are the symptoms of glaucoma?

There are no symptoms initially. Vision stays normal, and there is no pain.

However, as the disease progresses, a person with glaucoma may notice his or her side vision gradually failing. Over time, the patient may lose the central vision. Thus glaucoma is often said to be the ‘theft of vision’.

How is glaucoma detected?

Glaucoma is detected through a comprehensive eye exam that includes:

1. Visual acuity test.
   
2. Visual field test. This test measures your side (peripheral) vision.
   
3. fundal examination
   
4. Tonometry
   

People with the risk factors for glaucoma should have a comprehensive eye examination every one to two years, especially for those over the age of 40.

Can glaucoma be treated?

Treatment can delay progression of the disease, but cannot restore lost vision. Early diagnosis is thus very important.

Glaucoma treatments include medicines, laser, surgery. Medicines, in the form of eyedrops, are the most common early treatment for glaucoma. Some medicines cause the eye to make less fluid. Others lower pressure by helping fluid drain from the eye.

Because glaucoma often has no obvious symptoms, people may be tempted to stop taking, or may forget to take, their medicine. If you are being treated for glaucoma, be sure to take your glaucoma medicine every day. See your eye doctor regularly, and have a good compliance of medications to prevent disease progression.

被青光眼嚴重破壞的視神經線乳頭

正常的視神經線乳頭

什麼是表光眼？

青光眼是由於眼球壓力(眼壓)過高而造成視神經毁壞的一種眼疾，最終可導致失明。在香港，青光眼是首要 (23%) 致盲的原因。

有什麼類型的青光眼？

1. 開角型青光眼(慢性)
   
2. 閉角型青光眼 (可以是急性或慢性)
   
3. 繼發性青光眼；因創傷、炎性等引發
   
4. 先天性青光眼
   

開角型青光眼是常見的一種青光眼病症。由於眼睛排水角的海綿狀微小管道蔽塞，以致眼壓上升。最終毁壞視神經線。
開角型青光眼發展很慢，並沒有明顯病徵。

閉角型青光眼是因為眼睛的虹膜根部排水角房角閉塞引起，導致眼壓上升。它可以是急性或慢性。急性閉角型青光眼的病徵是眼痛、眼紅、視力模糊、頭痛和作嘔。它的成因是眼壓急劇上升引起。慢性閉角型青光眼可以是由急性事故或原發性引起。

以下資訊主要針對慢性青光眼：
有那些高危因素可令患青光眼機會增加？

• 年過 60 歲
  
• 家族有青光眼
  
• 糖尿病患者
  
• 深度近視、虹膜炎、服用類固醇s

青光眼有何病徵？

最初並無明顯徵。病者沒有痛楚，視力亦如常。但是，病者的外圍視野會逐漸收縮。隨著時間，病者會喪失中央視力。所以，青光眼常被稱為『視力的小偷』。

如何診斷青光眼？

全面的眼睛檢查可及早診斷青光眼，這包括：

1. 視敏度檢查
   
2. 視野檢查，以測度周邊視力敏感度
   
3. 眼底鏡檢查
   
4. 眼壓測度
   

年過 40 歲而有高危因素的人士，應每一至兩年接受一次檢查。

有什麼方法治青光眼？

治療可減慢視力受損，卻無法補救巳失去的視力。及早的診治最為重要。
治療旳方法包藥物、激光、手術。眼藥水是治療初期青光眼最常用的藥物。藥物的作用減低眼內房水製造，或增加其排出眼球。
因為青光眼並無明顯病徵，患者可能會忘記或停止用藥。切記每天用藥，並定期覆診，以防病情惡化。