Pigment Dispersion Syndrome

Dr Ben Wild

Overview

Just like a soccer ball, the eye must stay pressurized to function properly. Normally, the eye is inflated by the production of fluid, called the aqueous humor. This fluid circulates around the inside of the eye providing nutrients and removing wastes created by many eye structures. It exits at the root of the iris, the colored part of the eye, called Schlemm’s canal. Schlemm’s canal is separated from the inner contents of the eye via a fine sieve, called the trabecular meshwork. The interplay between aqeous humor production and the resistance created by the density of the trabecular meshwork creates the pressure inside the eye.

Front view (left) and sagittal view (right) of a healthy eye.

Pigment dispersion syndrome is typically a bilateral (both eyes) condition whereby the iris develops in such a way that it bows backwards and rubs against the zonules (strings that hold the lens of the eye in place). This continual rubbing results in the pigment granules, that give the iris its color, becoming liberated from the iris. These floating granules follow the same flow as the aqueous humor and start to accumulate on the lens of the eye, the cornea, and most importantly, the trabecular meshwork. The trabecular meshwork then becomes blocked with pigment and creates even more resistance for aqueous humor outflow leading to elevated eye pressures. These elevated pressures can lead to glaucoma in about 35% of affected individuals.

Frontal view showing pigment granules on the cornea (left) and sagittal view showing the iris bowing and pigment granules on the cornea, lens, trabecular meshwork and retina

Signs and Symptoms

Signs

Pigment granules stuck to the inside of the cornea, granules stuck to the lens, granules floating in the eye, granules depositing on the retina, elevated eye pressures, and the loss of iris pigment where the zonules are located.

Symptoms

Usually no symptoms but sometimes, if severe, can lead to fast onset of blurring vision, headache, and glare often after exercising.

Causes and Risk Factors

Causes

Abnormal development of the eye leading to the iris bowing backwards and rubbing on the zonules.

Risk Factors

High myopia (nearsightedness), male gender, Caucasian ethnicity.

Prevention and Treatment

Prevention

There is no known way to prevent pigment dispersion syndrome but treatments can ensure it does not lead to glaucoma.

Treatments

· Regular glaucoma testing with imaging and peripheral vision testing.

· Laser peripheral iridotomy to stop the iris from bowing backwards.

· Pilocarpine drops before exercising, this shrinks your pupil to straighten out the iris.

· Laser trabeculoplasty to remove the pigment in the trabecular meshwork.

Prognosis

Pigment dispersion syndrome itself is not a condition that will affect vision but it does put the individual at a higher risk of developing glaucoma, a condition that can lead to the development of large, irreversible, blind spots. Early detection and proper management can ensure that this condition will not affect one’s vision.