Pigment-dispersion syndrome
Overview
Pigment dispersion syndrome (PDS) is an affliction of the eye that, if left untreated, can lead to a form of glaucoma known as pigmentary glaucoma. It takes place when pigment cells slough off from the back of the iris and float around in the aqueous humor. This is not what causes problems; however, if the pigment flakes clog the trabecular meshwork, preventing the liquids in the eye from draining, pressure can build up inside the eye. This pressure can cause permanent damage to the optic nerve. This condition is rare, but occurs most often in Caucasians, particularly men, and the age of onset is relatively low: mid 20s to 40s. Most sufferers are nearsighted. There is no cure as of yet, but PDS can be managed with eye drops or treated with simple surgeries. If caught early and treated, chances of glaucoma are greatly reduced. Sufferers are often advised not to engage in high-impact sports such as long-distance running or martial arts, as strong impacts can cause more pigment cells to slough off.
Symptoms
Pigment dispersion syndrome (PDS) is generally an asymptomatic disorder discovered upon routine evaluation. Pigmentary glaucoma, a sequela of PDS, may likewise be asymptomatic, or it may present with complaints related to episodic rises in intraocular pressure, such as colored haloes around lights, blurred vision or subtle ocular pain. Both conditions are typically encountered in young, white males between the ages of 20 and 40 years. Myopia is also a commonly associated finding. With the slit lamp, patients with PDS and pigmentary glaucoma demonstrate bilateral liberation of iris pigment in the anterior chamber. Often, this is seen as a granular brown vertical band along the corneal endothelium, known as Krukenberg's spindle. You may also see pigment dusting on the lens, the surface of the iris and at Schwalbe's line. With the gonio lens, you may see dense pigmentation, which looks similar to melted chocolate, covering the trabecular meshwork in 360 degrees, though it will be most prominent in the inferior quadrant. The angle itself remains patent, and in some cases appears atypically wide open. Radial, spoke-like transillumination defects of the mid-peripheral iris are another common finding. While the intraocular pressure is normal in PDS, it may rise sharply in cases of pigmentary glaucoma, particularly after vigorous exercise or pharmacologic dilation. Likewise, PDS presents with a normal optic nerve appearance, while patients with pigmentary glaucoma manifest evidence of glaucomatous optic atrophy and associated field loss.
Treatment
Doctors usually treat pigmentary glaucoma with eyedrops such as Betagan, Timoptic, Optipranlol and Xalatan. These eyedrops have a relatively low incidence of side effects and are generally well-tolerated in younger patients. Doctors may also use medications such as Pilocar, and Ocusert, which are from a class of drugs called miotics. These medications cause the pupil to constrict (become smaller) and inhibit the iris from rubbing against the supporting fibers of the eye’s lens, helping to prevent further release of pigment. However, miotics have side effects such as blurred vision which can limit their use. In some patients, a laser treatment called argon laser trabeculoplasty works well. This procedure helps open up the drainage system in the eye to increase fluid flow, which lowers eye pressure and protects the optic nerve. Another treatment for pigmentary glaucoma is a procedure called a laser iridotomy. A laser is used to make a small hole in the iris, causing the iris to move away from the lens of the eye. This prevents the lens fibers from scraping the pigment from the iris and clogging the eye’s fluid flow. However, it has limitations and does not always achieve its desired effect. Researchers are now conducting more evaluations of this procedure to determine its effectiveness.