The iris is the colored part of the eye. Pigment dispersion syndrome (PDS) occurs when pigment rubs off the back of the iris and floats freely in the eye. Pigment pieces can block the eye’s drainage system and create problems with pressure.
The eye contains a clear fluid called aqueous humor. Regulating the amount of aqueous humor present allows the eye to maintain constant pressure using a drainage system. In PDS, flakes of pigment block the eye’s drainage system and pressure builds, damaging the optic nerve. When PDS advances to this state, doctors call it pigmentary glaucoma.
PDS is often underdiagnosed because it primarily affects people in their 20s and 30s. An eye doctor usually discovers it during a routine eye exam.
This article examines the symptoms, causes, risk factors, and treatment for PDS. It also describes the outlook for people with the condition.
PDS often has no symptoms. However, some people may experience blurred vision or see “halos” following exercise.
Even if PDS advances to pigmentary glaucoma, it may not cause symptoms. However, with increased damage to the optic nerve, blank spots may appear in the field of vision. These may be difficult to notice until they are large.
Tiny fibers called zonules attach to the lens in the eye and hold it in place.
In some people, these zonules rub against the back of the iris and cause pieces of pigment to flake off. The pigment then floats into the fluid in the eye and can block its drainage system.
Strenuous forms of activity such as jogging and basketball may increase the risk of PDS.
PDS has a genetic link and may pass from biological parents to their children. The risk of developing PDS increases among:
- nearsighted people
- those in their 20s and 30s
- white people
Nearsightedness seems to be a particularly important risk factor for PDS. Experts suggest the two may co-occur in up to 80% of people.
PDS often occurs without symptoms. An eye doctor may diagnose it during a regular eye exam as they run one or more of the following tests:
- an eye pressure test
- a gonioscopy to test the eye’s drainage
- an examination of the optic nerve
These are the same tests eye doctors use to diagnose glaucoma. They will look for pigment granules in the eye or pigment missing from the back of the iris.
Before recommending treatment, doctors may choose to use watchful waiting to monitor the condition’s progression.
Below are some common treatments.
PDS treatment usually includes eye drops, such as:
- levobunolol (Betagan)
- timolol (Timoptic)
- metipranolol (Optipranlol)
- latanoprost (Xalatan)
These eyedrops do not typically cause side effects, and most people tolerate them well.
Doctors may prescribe a type of miotic medication. These drugs help the pupil shrink in size, which may prevent the iris from rubbing against the fibers that support the lens. However, miotics can cause blurred vision and are not the right option for everyone. An example of a miotic is pilocarpine ophthalmic (Pilocar/Ocusert).
A treatment called laser trabeculoplasty is available for some patients. This procedure involves opening the drainage channel inside the eye to release pressure and prevent damage to the optic nerve.
Doctors may also recommend a laser iridotomy. During this procedure, a doctor uses a laser to makes a small hole in the iris, which pushes it away from the lens. This prevents the lens fibers from scraping off pigment from the iris. This procedure is only sometimes successful and research into its effectiveness is underway.
PDS is likely a result of an individual’s eye anatomy. Daily activities such as reading may cause chafing or rubbing between the lens and iris.
Strenuous exercise may also cause increased pigment shedding in some people. For people at high risk of developing PDS, doctors may prescribe medication for eye pressure to take before activity. They may also recommend abstaining from strenuous exercise.
According to the Genetic and Rare Diseases Information Center, about 30% of people with PDS go on to develop pigmentary glaucoma, and it may occur three times more frequently in males than females. This type of glaucoma is currently underdiagnosed because it occurs at a younger age than other forms and has no symptoms.
Pigmentary glaucoma responds well to treatment when doctors diagnose it early.
PDS can also diminish over time and eye pressure may return to normal.
The iris is the colored part of the eye. PDS occurs when pigment rubs off the back of the iris and floats freely into the eye. Fibers that hold the lens in place near the iris cause the rubbing.
The eye contains fluid in the center. It brings in new fluid and drains out the old. With PDS, pieces of pigment can lodge in the drainage system and prevent the old fluid from escaping. This increases pressure in the eye, leading to pigmentary glaucoma. When pressure is high for too long, it damages the optic nerve.
Because PDS does not usually cause symptoms, eye doctors often notice it during routine appointments. It is treatable with eyedrops, medications, or sometimes laser surgery.