Glaucoma is grouped by what is happening at the drainage angle, the narrow space where the edge of the iris meets the cornea. The doctor examines it with a mirrored contact lens, a test called gonioscopy, or measures it with an OCT scan.
Open-angle glaucoma
This is the most common type. The angle is wide open, but the drainage mesh inside it does not work as well as it should, for reasons that are not fully understood. Fluid builds up slowly, and the pressure creeps up over months and years.
It causes no pain or blur until it is advanced. The nerve fibres serving side vision are lost first, so most cases are found during a routine check-up, or late, when one eye is already badly affected. Both eyes are usually involved, one more than the other.
Variations
- Normal-tension glaucoma. The nerve is damaged even though the pressure is in the normal range. It is more common in older people and those with poor circulation.
- Pigmentary and pseudoexfoliation glaucoma. Pigment from the iris, or flakes of protein material, clog the drainage mesh.
- Ocular hypertension. The pressure is high but the nerve shows no damage. Not everyone needs treatment, but everyone needs regular checks, and treatment starts if the risk of damage looks high.
Treatment
Drops, laser trabeculoplasty or surgery, depending on how advanced the disease is and how well the pressure responds.
Angle-closure glaucoma
Some eyes are built with a narrow angle, where the iris sits very close to the drainage mesh. This is more common in long-sighted eyes and as the natural lens thickens with age. If the iris is pushed against the mesh, it blocks the drainage.
Acute angle closure: an emergency
If the angle closes suddenly, the pressure shoots up within hours.
Seek eye care immediately if you have
- sudden, severe eye pain, often with headache
- blurred vision and coloured haloes around lights
- a red eye
- nausea or vomiting with any of the above
Go to an emergency room if you cannot reach us. Treated quickly, the pressure can often be brought down before lasting damage is done.
Treatment starts with medicines to lower the pressure, followed by laser iridotomy, which makes a tiny opening in the iris so fluid can flow freely again. The other eye is usually treated too, as a precaution.
Chronic angle closure
The iris can also seal over the drainage mesh slowly, a little at a time. There is no pain or redness until the pressure is very high, so it is often found late. Once a large part of the angle has sealed, laser alone may not be enough, and long-term drops or surgery are needed.
Secondary glaucoma
Inflammation inside the eye, an injury, previous surgery, advanced diabetic eye disease and some other conditions can also raise the pressure. Both the glaucoma and its cause need treatment.
This guide explains; it does not diagnose. Your doctor’s advice about your own eyes comes first.