An Overview of Pigmentary Dispersion Syndrome

Pigmentary dispersion syndrome (PDS) is a disorder often detected during a routine eye examination. PDS occurs when pigment from the back of the iris, the colored part of your eye, is slowly released into the internal fluid that fills the front part of the eye. This fluid, called aqueous humor, carries the pigment in a cyclic manner through the front part of the eye and out to the eye's drainage canal, called the trabecular meshwork. If enough pigment is released, it can begin to plug up this drainage canal and prevent the fluid from flowing out properly. When this occurs, the pressure inside the eye may build up and cause pigmentary glaucoma.

Symptoms

Symptoms of PDS are most likely caused by sudden increases in eye pressure. The condition can cause episodes of symptoms, including the following:

• Blurred vision
• Colored halos around lights
• Mild ocular pain

Risk Factors

While anyone can develop PDS, it seems to be much more common in younger, white males between the ages of 20-40. Interestingly, most people who develop PDS are nearsighted.

Causes

PDS is caused by excess pigment floating around in the eye that has been released from the backside of the iris. Some people have unique eye anatomy that causes the lens zonules to rub abrasively onto the back of the iris. Lens zonules are thin fibers that hold the crystalline lens of the eye in place right behind the iris. As the iris and lens change shape, the zonules chafe against the iris and the pigment begins to flake off.

Diagnosis 

Because the pigment floats around, it gets deposited onto the back surface of the cornea in a vertical pattern. In eye care, this pigmentary deposition is known as “Krukenberg’s spindle.” Because this pigment comes off the back of the iris, the healthcare provider can also see “transillumination of the iris.” That means the healthcare provider sees slit-like defects in the iris where light passes through because of the lack of pigment. By using a procedure called gonioscopy, in which a special lens is placed on to the cornea after numbing drops are instilled, they can observe excess pigment that is deposited in the drainage canal of the eye. Eye pressure may or may not be elevated. If the patient has developed pigmentary glaucoma, then signs of glaucoma can also be seen.

What Else You Should Know

It is important to note that all people that have PDS will not develop pigmentary glaucoma. Eye pressure may fluctuate widely in patients with PDS or pigmentary glaucoma. The risk of progressing from PDS to pigmentary glaucoma is estimated to be about 35% to 50%.

Do not be surprised if your healthcare provider asks you about your exercise habits. PDS symptoms seem to occur more during exercise. It is thought that the vigorous movement of exercise may cause more pigment to be released. When more pigment is released, eye pressure can rise and cause the associated symptoms.

The best thing you can do is to return for examinations annually or more often as directed by your healthcare provider. Pigmentary glaucoma, unlike the more common “open-angle glaucoma,” should be diagnosed quickly and treated aggressively.