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General Information ⬇

Definition

Pigment dispersion refers to the release of pigment granules into the anterior chamber. It results from backward bowing of the peripheral iris (reverse pupillary block) with friction between the iris pigment epithelium and the zonular fibers. Pigment is released and may ultimately obstruct the TM, leading to increased IOP and secondary open-angle glaucoma.

Symptoms ⬆ ⬇

Mostly asymptomatic but may have blurred vision, eye pain, and colored halos around lights after exercise or pupillary dilation. More common in young adult, myopic men (age 20 to 45 years). Usually bilateral, but asymmetric. May have lattice degeneration and increased risk of a retinal detachment.

Signs ⬆ ⬇

(See Figures 9.10.1 and 9.10.2.)

Critical

Midperipheral, spoke-like iris TIDs corresponding to iridozonular contact; dense homogeneous pigmentation of the TM for 360 degrees (seen on gonioscopy) in the absence of signs of trauma or inflammation.

Other

A vertical pigment band on the corneal endothelium typically just inferior to the visual axis (Krukenberg spindle); pigment deposition on the posterior equatorial lens surface (Zentmayer line or Scheie line), on the anterior hyaloid face, slightly anterior to Schwalbe line (Sampaolesi line), and sometimes along the iris (which can produce iris heterochromia). Pigment on the posterior lens capsule is nearly pathognomonic. The angle often shows a wide ciliary body band with 3+ to 4+ pigmentation of the posterior TM, homogenous for 360 degrees. Pigmentary glaucoma is characterized by pigment dispersion syndrome plus glaucomatous optic neuropathy. Typically, large fluctuations in IOP can occur, during which pigment cells may be seen floating in the anterior chamber.

9-10.2 Pigment dispersion syndrome with a vertical band of endothelial pigment (Krukenberg spindle).

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9-10.1 Pigment dispersion syndrome with spoke-like iris transillumination defects.

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Differential Diagnosis ⬆ ⬇

  • Exfoliative glaucoma: Iris TIDs may be present, but are near the pupillary margin and are not radial. White, flaky material may be seen on the pupillary border, anterior lens capsule, and corneal endothelium. TM is highly pigmented but in a “splotchy” pattern, often with pigment anterior to Schwalbe line (also seen in PDS). See 9.11, PSEUDOEXFOLIATION SYNDROME/EXFOLIATIVE GLAUCOMA.
  • Inflammatory open-angle glaucoma: White blood cells and flare in the anterior chamber; no radial iris TIDs; often PAS on gonioscopy. TM pigment concentrated inferiorly. See 9.7, INFLAMMATORY OPEN-ANGLE GLAUCOMA.
  • Iris melanoma: Pigmentation of the angular structures accompanied by either a raised, pigmented lesion on the iris or a diffusely darkened iris. No iris TIDs. See 5.13, MALIGNANT MELANOMA OF THE IRIS.
  • Irradiation: Induces atrophy and depigmentation of the ciliary processes with increased TM pigment deposition.
  • Postoperative pigment liberation after posterior chamber intraocular lens implantation.
  • Siderosis.
  • Iris chafe with sulcus IOL: Iris TIDs outlining the haptics may be seen.
  • Bilateral acute depigmentation of the iris: Acute-onset bilateral iris depigmentation, pigment dispersion in the anterior chamber, and heavy pigmentation of the TM. Usually symmetric (versus pigment dispersion syndrome which is typically asymmetric). Alternatively, if accompanied by a mydriatic pupil that is poorly responsive to light with sphincter paralysis, consider bilateral acute iris transillumination.

Work Up ⬆ ⬇

Workup
  1. History: Previous episodes of decreased vision or halos? Symptoms associated with exercise? Trauma, surgery, or previous intraocular foreign body?
  2. Slit lamp examination, particularly checking for iris TIDs. Large defects may be seen by shining a small slit beam directly into the pupil to obtain a red reflex. Look for Krukenberg spindle on the corneal endothelium. Look for pigment on the posterior lens equator by angling the slit beam nasally and having the patient look temporally (Zentmayer line or Scheie stripe; pathognomonic for pigment dispersion). Examine the angle looking for dense, evenly dispersed TM pigmentation. Careful retinal examination because of increased incidence of lattice degeneration and retinal detachment.
  3. Perform baseline glaucoma evaluation. See 9.1, PRIMARY OPEN-ANGLE GLAUCOMA.

Treatment ⬆ ⬇

Similar to POAG. Depends on IOP, optic nerve damage, and symptom extent. Usually patients with pigment dispersion without ocular hypertension, glaucoma, or symptoms are observed carefully. A stepwise approach to control IOP is usually taken when mild-to-moderate glaucomatous changes are present. When advanced glaucoma is discovered on initial examination, maximal medical therapy may be instituted initially. See 9.1, PRIMARY OPEN-ANGLE GLAUCOMA.

  1. Decrease mechanical iridozonular contact. Two methods have been proposed:
    • Miotic agents: A theoretical first-line therapy because they minimize iridozonular contact. However, because most patients are young and myopic, the resulting fluctuation in myopia may not be tolerated. In addition, approximately 14% of patients have lattice retinal degeneration and are thus predisposed to retinal detachment from the use of miotics. In some cases, pilocarpine 4% gel q.h.s. may be tolerated.
    • Peripheral laser iridotomy: Laser PI has been recommended to reduce pigment dispersion by decreasing iridozonular contact, but remains controversial. It may be best suited in early-stage disease and ill-advised in more advanced stages.
  2. Other antiglaucoma medications. See 9.1, PRIMARY OPEN-ANGLE GLAUCOMA.
  3. SLT or ALT. Due to greater risk of postlaser IOP spikes, lower energy should be used, and only 180 degrees of treatment is advised initially. Careful postlaser monitoring is needed to detect early IOP rise.
  4. Consider MIGS surgery, guarded filtration procedure, or tube shunt when medical and laser therapies fail. These young myopic patients are at greater risk for hypotony maculopathy and surgical technique should aim to avoid early overfiltration.

Follow Up ⬆

Same as POAG. See 9.1, PRIMARY OPEN-ANGLE GLAUCOMA.