Acute Angle closure glaucoma & prevention of acute glaucoma David Kinshuck |
This page describes acute angle closure and its prevention. See chronic narrow angle glaucoma
|
|
Anatomy |
|
Anotomy of the eye. Close up on right, fluid flow as below. |
|
Blockage to aqueous flow |
The eye is partly filled with a watery fluid, called 'aqueous'. The aqueous is made in the middle chamber of the eye, secreted by the ciliary body. The aqueous fluid normally flows forward into the front chamber, and leaves the eye in a the eye's drainage system (the trabecular meshwork and hen the canal of schlemm). From the drain (canal of schlemm), the aqueous flows into the blood stream. (This has nothing to do with tears; tears cover the front surface of the eye only.) In open angle glaucoma the blockage is in the trabecular meshwork. In narrow angle glaucoma the iris moves forward and blocks the 'angle'. |
What is eye pressure? |
|
Here is the normal aqueous flow. |
aqueous
fluid flow, shown in blue (blue)
|
Why does the eye pressure go up? |
|
If the drain of the eye blocks or is blocked, the fluid cannot drain out of the eye. The optic nerve is the 'electric wire' of the eye that takes messages about what you see to the brain. |
As
aqueous fluid cannot drain out of the eye, flow is directed back and
pressure rises
|
What is glaucoma? |
|
The pressure presses on the optic nerve at the back of the eye, and as the nerve is damaged the sight becomes reduced. As nerve becomes damaged, examination may show the damage as 'caved in'. Medically we call it 'cupped'.
|
![]() |
What is angle closure glaucoma? |
If you have angle closure glaucoma your eye (especially the front chamber) is smaller than normal. |
|
normal eye & fluid flow
|
![]() |
small eye...small eyes are more prone to narrow angle/acute glaucoma
aqueous is 'made' in the ciliary body (blue blob), but cannot flow past the iris or out of the eye the normal way. Pressure is transmitted to the optic nerve which it damages. The aqueous pushes the iris forward (see below) and animation |
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. Ethnicity and acute glaucoma |
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. |
![]() |
What do you notice? |
As above, there are different presentations.
|
Laser treatment |
|
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 The laser The laser hole Month after
laser
laser iridotomy, visible at 12.30 o'clock,
|
![]() The
hole made with laser
|
hole
made with laser allows fluid flow out of eye |
After laser |
|
Laser completely
prevents an 'attack' of acute glaucoma, so this will never be a problem. Sometimes the may be chronic angle closure despite laser. |
![]() |
Cataract surgery in angle closure glaucoma |
|
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 As cataract surgery is becoming safer ophthalmologists are starting to recommend cataract surgery for patients with narrow angles . Ethnicity and acute glaucoma |
aqueous flow in a younger patient |
aqueous flow in a older patient (rarely patients can be younger...they will have small eyes) |
|
aqueous flow is free again after cataract surgery
|
Topiramate |
|
This is a new treatment for severe epilepsy and migraine. Unfortunately it may cause angle closure glaucoma, see. Treatment is DIFFERENT FROM ordinary ACUTE GLAUCOMA see |
For Professionals |
See this page |
Leaflet download |
|
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 address of this site ('org' changing to 'nhs') is changing from http://www.goodhope.org.uk/departments/eyedept/ to http://www.goodhope.nhs.uk/departments/eyedept/ |
|