What is Glaucoma?

Glaucoma is a group of eye conditions in which the optic nerve (the main nerve that takes visual information from the eye to the brain) becomes damaged. This can be due to a rise in intra-ocular pressure (IOP) but is not always the case.

If diagnosed early, treatment can prevent further damage to vision. However, if left untreated, this damage (neuropathy) can ultimately cause blindness.

Glaucoma has been called the "silent thief of sight" because it is gradual and normally  asymptomatic until quite advanced.

What are the symptoms of Glaucoma?

Primary Open-Angle Glaucoma (POAG) generally has no symptoms in the early stages, which is why it is known as the "silent thief of sight. Late stage glaucoma, if untreated, leads to loss of visual field. If this is in one eye only, it may go unnoticed until vision is profoundly affected.

An attack of Acute Angle Closure, a different type of the disease, will normally cause a red, painful eye with misty vision and haloes around bright lights. This normally occurs in small hyperopic (long-sighted) eyes. The pain can be bad enough to cause nausea and vomiting. Repeated closed angle attacks and/or a sustained raised IOP can lead to damage to the optic nerve, known as primary angle-closure glaucoma (PACG).

What are the causes of Glaucoma?

There are four main types of glaucoma:

Congenital glaucoma
A rare but serious developmental abnormality of the eye causing glaucoma.

Secondary glaucoma
There are several possible causes including inflammation, trauma, surgery and syndromes such as pigment dispersion and pseudo-exfoliation. These cause raised IOP and glaucoma.

Pigment dispersion syndrome (PDS) is when pigment is released from the iris which may then lead to a blockage of the drainage canals, a rise in eye pressure and damage to the optic nerve. This is known as pigment dispersion glaucoma.

Pseudo-exfoliation (PXF) is a rare condition caused by a build-up of abnormal protein which may block the outflow of fluid, cause raised eye pressure and my lead to optic nerve damage.

Primary open-angle glaucoma (POAG)
This is the most common form of glaucoma.Ten percent of over 75 year olds will have some form of POAG.The drainage angle of the eye is damaged, preventing the correct amount of fluid from draining away, leading to a raised IOP and damage to the optic nerve.

It tends to run in families with raised intra-ocular pressure the biggest risk factor in POAG. However, glaucoma can occur in patients with "normal" intra-ocular pressure (normal tension glaucoma).

Other risk factors include age, corneal thickness, ethnicity, myopia (short sightedness) and diabetes.

Primary angle-closure glaucoma (PACG)
This is a much rarer condition in the UK which occurs when the drainage angle between the iris and cornea, through which fluid passes, is unusually narrow and can become closed off. When this occurs, the inner eye pressure rises sharply causing pain, nausea, blurred vision and redness in the eye.

It also tends to run in families, with hyperopic (long-sighted) eyes more at risk. Women are three times more likely to suffer from closed angle attacks.

What is the treatment for glaucoma?

Treatment for POAG is normally with eye drops but may require laser or surgical procedures. PACG may require laser treatment, surgery and/or medical treatment.

Types of laser treatment for glaucoma:

Selective Laser Trabeculoplasty (SLT)
Uses a cool laser to promote drainage. It can be used when the glaucoma is first diagnosed instead of drops, or to compliment drop therapy.

Micropulsed Diode Laser Trabeculoplasty (MLT)
The same risk, effectiveness and repeatability profile as SLT but uses a different laser wavelength. MLT uses a laser which switches on and off as many times per "shot" and hence proclaims to cause less inflammation and improve safety.

iStent
A microsurgical procedure where a micro trabecular bypass implant helps to drain fluid from the eye and therefore reduces eye pressure. It can be used in combination with cataract surgery.

Hydrus TM by-Pass stent

This technique involves a larger more supporting stent being placed across the trabecular meshwork. Similar to the istent in technique and effectively lowers the eye pressure.

Omni viscocanalostomy

Is a stentless technique performed inside the eye to reduce obstructions in the natural outflow of the eye, it lowers the pressure in the eye without the need for stents.

Xengel stents

These flexible collagen stents are useful when the natural drainage channels in the eye no longer are effective to control the pressure. The tube exits under the thin white layers of the eye allowing fluid to pass into a bleb. They are less traumatic to the eye than a trabeculectomy with a faster surgery and recovery time.

Trabeculectomy
An operation to lower the pressure in the eye by creating a new drainage channel in the eye, through which fluid drains out into a space under the outer layer of the eye (conjunctiva). This filtering area is called a bleb.

For further information please contact Suzanne Quilter at isec@southeasteyesurgeon.co.uk who can supply you with an information sheet or alternatively book to make an appointment.