• Anatomy
• What is eye pressure?
• Why does the eye pressure go up?
• What is glaucoma?
• What is angle closure glaucoma?
  
  
• What do you notice?
• What is the laser treatment?
• Will you need drops for ever?
  
  
• Cataract surgery
• topiramate
  
  
  
• Chronic glaucoma..when to laser
• Ultrasound appearance
• for professionals
• how to laser PIs
  
  
• Leaflet download
• Animation
  
  
• a case
• www.eyemdlink.com
• common in Taiwan
  

Fluid is secreted by the ciliary body and passes through the anterior chamber to the eye's drainage system. Close up on right, fluid flow as below.

Your eye is partly filled with a watery fluid, called 'aqueous'. The aqueous is made in the middle chamber of the eye. The aqueous fluid normally flows forward into the front chamber, and leaves the eye in a the eye's drainage system. From the drain, it flows into the blood stream. (It has nothing to do with tears; tears cover the front surface of the eye only.)
The diagram opposite shows how aqueous flows. Medically the middle chamber is known as the 'posterior' chamber, and the front chamber the 'anterior' chamber. Aqueous flows from the posterior to the anterior chamber.

If the fluid cannot drain out of the eye, the pressure in the eye goes up. This is like a tyre being pumped up and going a little 'hard'.
The extra pressure then presses on the nerve at the back of the eye.

The optic nerve is the 'electric wire' of the eye that takes messages about what you see to the brain. If the nerve is damaged your sight becomes reduced.

See animation

This is explained in detail on the related page glaucoma. Briefly, the pressure presses on the optic nerve at the back of the eye.

The nerve becomes damaged; if your eye is examined the nerve may appear caved in; or we call it 'cupped'.

Because the eye is smaller than usual, in this condition a blockage develops, shown opposite, where the iris (the pupil) and lens are in contact.

As a result there is not enough space for the aqueous fluid to flow to the front chamber of the eye and out of the eye.

Then... the fluid pushes the iris even further forward, trapping more fluid in the eye (blocking the entrance to the drainage system). As the aqueous fluid cannot drain out of the eye, this puts the pressure up and damages the optic nerve.

This is explained better in this animation

This blockage can develop all of a sudden, perhaps one day coming out of the dark into a well lit room, as the pupil reaches a 'mid-dilated' size. This causes 'acute glaucoma'.

The blockage may be more gradual, 'chronic narrow angle glaucoma'.

Alternatively, you may have open angle glaucoma (see) and then this extra blockage may develop...'open angle glaucoma with narrow angles'.

There are many different terms used to describe these conditions.

a partial blockage develops here (black) where the iris and lens are in contact

as the iris gets pushed forward, a secondary blockage develops here (black arrows) at the entry point to the trabecular meshwork and the canal of schlemm (the drainage system).

The iris...when it is pushed forward in this way blocks the entrance to the drain, so pressure goes up.

How to laser PIs for professionals

Laser is the main treatment for this condition. In acute glaucoma the pressure is lowered with tablets and drops, and the laser carried out in the next few days. New treatments are being investigated.

An hour before laser
Before the laser you need drops to make your pupil small. These may give you a headache. Tablets keep the eye pressure down for the first day, and these can make you feel a little funny, with pins and needles.

The laser
'Laser' is a type of very bright focused light. You sit at the laser machine, then drops are used to anaesthetise the front of your eye, and a small contact lens is placed on your eye. When the button is pressed you may feel a slight pain lasting a second or less.

The laser hole
The laser makes a tiny hole in the iris of your eye. The hole is invisible to the naked eye. Once the hole is made fluid can flow though to the front chamber and then out of the eye. This hole keeps the eye pressure down.

Week of laser
You need anti-inflammatory drops for 2 weeks (such as dexamethasone), as well as your regular glaucoma drops if you have any.

Month after laser
Many people do not need drops after 4 weeks. Occasionally the laser only goes half way through the iris, and you may need the hole completed a week or two later.

hole made with laser allows fluid flow out of eye

See animation

Laser completely prevents an 'attack' of acute glaucoma, so this will never be a problem.

However, some people with chronic angle closure glaucoma may still have a slightly high pressure even after laser, and they need drops indefinitely.
People ask why this is so: imagine an overflowing sink. If you remove the plug (with laser), there may still be a blocked drain.

The diagram opposite shows where the remaining blockage may remain (the black rectangle). Technically the blockage is in the trabecular meshwork, which is the drainage system of the eye.
The blue arrow is the site of the laser hole.
If you need drops you will be followed up in the outpatient clinic. If your doctor thinks you are lucky enough not to need drops, always have your eyes checked by your optometrist every year as a precaution.

See animation

Cataract
Thickening of the lens of the eye is part of the cause of angle closure glaucoma. This happens naturally as we get older, but may happen earlier if we develop a cataract.

As cataracts are common as we get older, (and more common in smokers), we are more prone to acute glaucoma as we get older.

Some patients with unusually small eyes may develop it at a younger age.

Cataract surgery
If you have a cataract then cataract surgery will also prevent attacks of angle closure glaucoma.

As cataract surgery is becoming safer ophthalmologists are starting to recommend cataract surgery for patients with narrow angles .

Ethnicity and acute glaucoma
Similarly some Asian patients (Taiwanese for example) or Inuits, have narrower anterior chambers and are far more prone to acute glaucoma at a younger age. In such communities screening services need to examine patients, to pick out patients who need laser iridotomies.

If you are a health professional and want to have a leaflet to give to give to patients, instead of this web page, see 120k Adobe PDF version.

This Publisher is a Microsoft Publisher document, and you are welcome to download it and print copies. You are welcome to make changes for your patients (you can edit the leaflet in Microsoft Publisher).

You will need M Publisher 2000 to open and print the document. M Publisher is bundled as part of Microsoft Office. The only condition is that you let me know if there are any errors.
The document is 150k. The document can be printed out and photocopied to provide a double-sided leaflet 1/3 A4 size for your patients. The address is http://www.diabeticretinopathy.org.uk/leaflets/angleclosureglaucoma.pub