Pigment dispersion syndrome

Overview

Pigment Dispersion Syndrome (PDS) is an ocular condition in which pigment granules, normally found on the back surface of the iris, are shed and dispersed into other parts of the eye, particularly the anterior chamber. These pigment granules can accumulate in the trabecular meshwork—the part of the eye responsible for draining aqueous humor—and may obstruct fluid outflow, potentially leading to increased intraocular pressure (IOP). If this pressure remains elevated, PDS can progress to pigmentary glaucoma, a form of secondary open-angle glaucoma. PDS typically affects young to middle-aged adults and is more common in males and individuals with myopia (nearsightedness).

Causes

Pigment Dispersion Syndrome results from a mechanical rubbing of the posterior iris surface against the zonules—the fibrous strands that hold the lens in place. This friction releases pigment granules into the aqueous humor, which then circulate and settle in various anterior segment structures of the eye.

Key contributing factors include:

• Genetic predisposition: There may be a hereditary component, with some familial clustering observed.

• Eye anatomy: Deep anterior chambers, concave iris configuration, and long axial length (common in myopic eyes) increase the likelihood of iris-zonule contact.

• Exercise and pupil movement: Activities that involve vigorous eye or body movement, or frequent dilation and constriction of the pupil, may exacerbate pigment release.

Symptoms

Pigment Dispersion Syndrome often develops silently and may go unnoticed in its early stages. When symptoms do appear, they can include:

• Blurry vision: Especially during or after exercise or dilation of the pupil

• Halos around lights: Caused by elevated IOP or pigment accumulation

• Intermittent eye discomfort: Or mild ocular pressure sensation

• Photophobia (light sensitivity): In some individuals

Because symptoms may be mild or absent, routine eye examinations are essential, especially in individuals at risk. If PDS progresses to pigmentary glaucoma, more noticeable vision changes and peripheral vision loss may occur.

Diagnosis

Diagnosis of Pigment Dispersion Syndrome is made during a comprehensive eye examination by an ophthalmologist or optometrist. Specialized diagnostic techniques help identify the characteristic features of PDS.

Key Diagnostic Tools:

• Slit-lamp examination: Reveals pigment granules on the corneal endothelium (Krukenberg spindle), iris transillumination defects, and pigment in the anterior chamber

• Gonioscopy: Allows visualization of the trabecular meshwork, where pigment accumulation can be seen

• Tonometry: Measures intraocular pressure to assess for potential glaucoma risk

• Visual field testing: To detect early signs of peripheral vision loss if glaucoma is suspected

• Optical coherence tomography (OCT): Imaging of the optic nerve and retinal nerve fiber layer to monitor for glaucomatous damage

Diagnosis is often incidental, discovered during routine screening, particularly in young myopic patients.

Treatment

Treatment of Pigment Dispersion Syndrome depends on the presence and severity of elevated intraocular pressure and whether glaucomatous changes have occurred. The primary goal is to prevent progression to pigmentary glaucoma.

Non-Surgical Management:

• Observation: In patients with normal IOP and no optic nerve damage, regular monitoring may be sufficient

• Medications:

  • Prostaglandin analogs (e.g., latanoprost) to improve aqueous outflow

  • Beta-blockers (e.g., timolol) to reduce aqueous humor production

  • Alpha agonists and carbonic anhydrase inhibitors as adjunctive therapy

Laser and Surgical Options:

• Laser peripheral iridotomy (LPI): Creates a small hole in the peripheral iris to flatten its configuration and reduce pigment release; results are variable

• Selective laser trabeculoplasty (SLT): Used if IOP remains high; enhances fluid outflow through the trabecular meshwork

• Glaucoma surgery (e.g., trabeculectomy): Considered in advanced cases resistant to medication and laser therapy

Lifestyle modifications, such as avoiding high-impact exercise that may exacerbate pigment shedding, may also be advised.

Prognosis

The prognosis for individuals with Pigment Dispersion Syndrome is generally good, especially when the condition is detected early and monitored regularly. Many individuals remain stable without progression to glaucoma. However, approximately 30% to 50% of patients with PDS may develop pigmentary glaucoma over time.

When managed appropriately with medications or laser therapy, intraocular pressure can be controlled, and the risk of vision loss significantly reduced. Lifelong monitoring is essential to ensure that pigmentary dispersion does not result in optic nerve damage or significant visual field loss.

With early intervention and adherence to treatment and follow-up schedules, most individuals with PDS can maintain good visual function and quality of life.