Pigmentary glaucoma also goes under the associated name Pigmentary Dispersion Syndrome (PDS) since it is the syndrome that leads to this form of glaucoma.
In the eye the iris surrounds the eye lens touching it slightly. It’s possible that rubbing between the iris and the lens can occur, in which case pigment from the iris can be shaved off gradually and the floating pigment left to move about in the aqueous humour that is the fluid behind the eye.
The aqueous humour in the eye needs to be replenished as it needs to be clear and fresh, and the “old” fluid needs to drain away slowly so as to not allow any reduction in eye pressure. The slow drainage is implemented by a very fine mesh called the trabecular meshwork, located where the cornea and the iris meet.
Now if the meshwork is blocked in any way – by say pigment from the iris – then pressure builds up within the eye. Pressure build up in the eye is the main cause of damage to the optic nerve that takes images seen by the retina to the brain for processing – such damage to the optic nerve is described medically as “glaucoma”
It’s possible to have pigmentary dispersion syndrome and not have any signs of damage to the optic nerve, neither any loss of field vision, in other words no signs of glaucoma. However, careful monitoring for signs of increased intra ocular pressure (IOP) in the eye and regular eye examinations need to be followed.
Who gets it?
Males more than females!
Men seem to be up to 2 times more prone to getting the syndrome than do women, and for the associated glaucoma it rises to 5 times. It seems that Caucasian men are more susceptible, and the age bracket is from 25 to 40 at which age the condition generally just seems to slow down and stop. Probably because once the pigment has rubbed off, there is none left to cause any further trouble.
Family history is a factor generally, but direct genetic correlation is not fully understood.
How is it detected?
It’s not easy to detect as there may be little or no symptoms for a sufferer to describe to a doctor, but a regular eye examination by an optometrist or ophthalmologist will present a good opportunity.
Loss of peripheral vision is a sign, but the loss may be so slow in developing that it goes unnoticed. Blurred vision or halo effects seen after exercise or maybe after being in the dark for a while, and confirmed by examination to mean increased eye pressure, can provide an indication.
Since strong exercise might be the cause of any rubbing between iris and lens, this is discouraged.
Monitoring for increased intra ocular pressure (IOP) within the eye is essential as this may be the factor in the syndrome progressing to a glaucoma. Repeating, fortunately it’s common for the pigment dispersion to cease and pressure to stabilise at a reasonable level.
Beta blocker and other medication eye drops help in reducing pigment dispersion, and they are easily utilised by patients and little or no side effects have been reported.
Various surgical procedures are available including:
• Laser trabeculoplasty is very effective for pigmentary glaucoma
• Surgical trabeculectomy creates a filtering space near the trabecular meshwork that takes over as a pressure release valve when the meshwork blocks up.
Whatever procedure is used depends upon the particular physical characteristics of the patient’s eye as well as considerations of how low the intra ocular pressure needs to be to avoid any further damage to the optic nerve and thus the vision.