Behind the cornea of the eye there is a fluid described as an “aqueous humour” which obviously needs to be replenished – you can’t have the same fluid all you life – and therein lies a problem – how to get rid of any excess.
Well, the aqueous humour excess is allowed to drain away through a very fine mesh. In that way the pressure within the eye can be maintained. The mesh is called the trabecular meshwork and is at the join between the iris and the cornea.
It’s possible for the angle between the cornea and iris to remain constant but the mesh clog up in some way – with the increase in pressure there is a distinct possibility of glaucoma developing. This type of glaucoma is called “open angle glaucoma”
(Now if for any reason the angle between the cornea and the iris closes up, then under these circumstances obviously no drainage can occur and a “closed angle glaucoma” can develop).
Pseudoexfoliation glaucoma is a secondary type of development to an open angle glaucoma since it is often found in association.
So what is pseudoexfoliation glaucoma?
Pseudo means “false” and exfoliation means “removal of dead surface cells” – in the case of glaucoma little white dandruff type flakes coat themselves on to the iris and lens of the eye. The description pseudo is used because there is no real exfoliation, it just looks that way.
The eye then develops a whitish look. The main problem with the insoluble flakes is they cause blockage of the meshwork which in turn gives rise to increased eye pressure, which is the cause of degeneration of the optic nerve.
Degeneration of the optic nerve, if not detected, leads to messages from the retina not being transmitted to the brain, and vision is impaired, eventually perhaps leading to total vision loss.
Who gets it?
As well as those over 50 and female, it’s thought that people in the northern hemisphere, particularly Scandinavian countries, are more prone to developing this variation in glaucoma. This leads to the suspicion that genes and population movements may be at work, although it may be that pristine clean air and high ultra violet light may be a factor.
The whitish look and presence of dandruff-like flakes is a giveaway, and further examination of the pattern and distribution provides confirmation.
Unfortunately the glaucoma may be well developed at this stage as there are little or no prior symptoms. It should be noted however that routine eye examinations by an eye doctor such as an optometrist or ophthalmologist will enable detection through early signs.
Treatment and outcome
As opposed to an “ordinary” open angle glaucoma, a pseudoexfoliation glaucoma does not respond to treatment nearly as well. The main reason for this is the usual treatment procedure of lowering the intra ocular eye pressure (IOP) using eye drops or other medication proves more difficult.
Difficulty in lowering pressure is one of the reasons that laser surgery on the trabecular meshwork to open up the drainage route is often considered. Laser surgery to the trabecular meshwork to relieve intraocular pressure that can lead to glaucoma is called laser trabeculoplasty.
Laser trabeculoplasty is relative effective for pseudoexfoliation glaucoma with few side effects. Typically this procedure starts to fade after around 5 years at which stage it will need repeating.