A Look at the Many Faces of Glaucoma – Part 2.
Dr. Megan Polack, Cowichan Eyecare
This month we’ll look at two conditions that involve a buildup of material inside the eye which can block the drainage of aqueous humour out of the eye, leading to glaucoma.
Pseudoexfoliation Syndrome and Pseudoexfoliation Glaucoma:
Pseudoexfoliation glaucoma is a type of openangle glaucoma characterized by tiny bits of white, flaky protein material deposited inside the eye on the crystalline lens, iris, trabecular meshwork and other parts of the eye. This material can only be seen with the magnification provided by the slit lamp biomicroscope during a full eye health exam and it can often only be seen after the pupils are dilated.
Therefore, having the dilation drops (drops that temporarily make your pupils big) is an important part of your routine eye health exams! The presence of the material alone without a diagnosis of glaucoma is termed pseudoexfoliation syndrome. Having the syndrome increases the risk of developing glaucoma because the material can block the drainage system of the eye, causing the pressure in the eye to increase.
About 25% of those with pseudoexfoliation syndrome develop elevated intraocular pressure, and of these people, about one-third have glaucoma. Patients with pseudoexfoliation syndrome are around six times more likely to develop higher than normal intraocular pressure (ocular hypertension) than patients without pseudoexfoliation syndrome.
Patients with pseudoexfoliation syndrome are also at higher risk for angle closure glaucoma and can have more complications during cataract surgery. Pseudoexfoliation increases with age and is most common in people over age 50 and in people of Scandinavian descent. It is thought to be present in about 5 percent of people age 75 to 85.
Pigment Dispersion Syndrome and Pigmentary Glaucoma:
Pigment dispersion syndrome (PDS) is characterized by deposits of pigment (originally from the iris) onto the back of the cornea, the trabecular meshwork and other areas inside the eye. It is not known exactly why this occurs but patients with PDS have a certain shape to their iris (concave) that allows it to rub on structures of the eye behind the iris and this releases pigment.
The pigment can only be seen with the slit lamp biomicroscope and is commonly picked up on routine eye exams of asymptomatic patients. It is usually present in both eyes. A test called gonioscopy is done to help confirm the diagnosis of PDS. Gonioscopy uses a special contact lens placed on the eye to look at the drainage angle. Those with PDS will have excess pigment in the angle of the eye.
Pigment dispersion is most common in Caucasian males who are nearsighted and who are between the ages of 20 and 50, but it can also occur in females and other age groups. Therefore, even if you are a young, healthy person with perfect vision, you should have routine (biannual) eye health exams with your Optometrist because you could have this syndrome without knowing it! PDS increases the risk of developing a type of glaucoma called pigmentary glaucoma (PG) by between 25 to 50%.
Similar to the pseudoexfoliative material discussed above, the excess pigment can clog up the drainage system of the eye and cause increased intraocular pressure. This does not usually have symptoms but some patients may notice halos, intermittent blurred vision and ocular pain or discomfort, especially following activities such as exercise, because this can cause excess pigment to be released in the eye. PDS is one condition where the release of pigment and therefore risk of increased intraocular pressure often reduces with age.
If your optometrist detects pseudoexfoliation or pigment dispersion syndrome during your eye health exam, they will likely monitor your intraocular pressure, visual field and optic nerves more often (every 6 to 12 months) to ensure that if glaucoma develops, it is caught early and treated appropriately.