Pigment Dispersion Syndrome and Pigmentary Glaucoma: An Overview

Orkun Kaymaz

Introduction

Pigment dispersion syndrome (PDS) and its potential sequel, pigmentary glaucoma, are characterized by the anomalous dispersion of pigment granules within the ocular structures. This overview discusses the clinical manifestation of these conditions and the management options including medical, laser and surgical treatment.

Aetiology, pathophysiology and risk factors

The primary cause of PDS and PG is the release of pigment into the anterior chamber due to the iris rubbing on the zonules and lens. Posterior bowing of the mid-peripheral iris and a reverse pupillary block are the reported anatomical anomalies which cause this deposition of pigment (1). This leads to increased intraocular pressure in the anterior chamber (AC). Risk factors include male sex, age 20-40 years, myopia, and Caucasian ethnicity. PDS is inherited as an autosomal dominant trait.

In eyes with PG, myopia tends to be more pronounced with a deep AC as well as the structural abnormalities (reverse pupillary block, posterior bowing and irido-lenticular touch). The pigment can be deposited in the trabecular meshwork (TM), causing decreased aqueous outflow and leading to elevated IOP and eventual secondary glaucomatous optic neuropathy (3).

Clinical presentation

Pigment deposition in the AC is a characteristic clinical feature of PDS/PG. This deposition can occur in different structures such as the corneal endothelium, where the pigment can line vertically and form Krukenberg spindles. Pigment can be deposited in the AC, posterior lens capsule (Zentmayer or Schie line) and on the anterior hyaloid-capsular ligament (Egger’s line) (1, 2). Iris-transilluminating defects can be detected.

Gonioscopy can reveal an open angle, pigment dispersion in the TM which is often homogenous and 360 degrees in circumference. The Schwalbe line may appear more pigmented inferiorly.

Retinal examination must be performed in confirmed PDS/PG to monitor optic neuropathy from potential glaucomatous changes. As there’s an increased risk of retinal lattice degeneration in PDS/PG, the retina must be examined for retinal detachment (2).

Management

Regular ophthalmic examination in clinic should be performed for patients with PDS to detect secondary pigmentary glaucoma. Medical management options are similar to that of POAG (4). This includes miotics such as pilocarpine which reduce irido-zonular contact and increase aqueous outflow, however it is usually poorly tolerated by younger patients and regular retinal examination is required due to possible side effects such as retinal detachment (2). Therefore, pilocarpine has been replaced by other topical options including prostaglandin analogues, carbonic anhydrase inhibitors, beta blockers and alpha-adrenergic agonists.

Peripheral iridotomy can be used to allow drainage of fluid from the posterior chamber to the anterior chamber and vice versa. However the effectiveness of this in PDS is inconclusive (5). Argon laser trabeculoplasty (ALT) is another option which is effective initially, however studies have shown that around two-thirds of patients will require further surgery within 10 years (6, 7). Selective laser trabeculoplasty (SLT) has shown to have similar efficacy to ALT and a concern of it is a IOP spike may follow immediately after the laser treatment, secondary to pigment release, this risk can be reduced by using aproclonidine pre-treatment and by using low energy laser settings (8). Both SLT and ALT are more effective in younger patients (6, 7, 8). Patients who show a deterioration in IOP despite medical or laser treatment should be considered for trabeculectomy.

Conclusion

PDS is a condition where there’s irido-zonular pigment release into the anterior chamber, commonly causing pigmentary glaucoma. Meticulous ophthalmic examination is crucial to aid diagnosis and appropriate management. Educating the patient, ensuring an accurate diagnosis, and implementing effective clinical management can reduce the necessity for more aggressive interventions and mitigate the risk of serious vision-threatening conditions like advanced-stage glaucoma.

References:

  1. Noecker RJ. Pigment Dispersion Syndrome and Pigmentary Glaucoma. In: Noecker RJ, ed. Glaucoma Medical Therapy: Principles and Management. Springer; 2008.
  2. Zeppieri M, Tripathy K. Pigment Dispersion Glaucoma. [Updated 2023 May 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK580495/
  3. Wang C, Dang Y, Loewen RT, Waxman S, Shah P, Xia X, Loewen NA. Impact of pigment dispersion on trabecular meshwork cells. Graefes Arch Clin Exp Ophthalmol. 2019 Jun;257(6):1217-1230. doi: 10.1007/s00417-019-04300-7. Epub 2019 Mar 28. PMID: 30919079; PMCID: PMC7847180.
  4. Scuderi G, Contestabile MT, Scuderi L, Librando A, Fenicia V, Rahimi S. Pigment dispersion syndrome and pigmentary glaucoma: a review and update. Int Ophthalmol. 2019 Jul;39(7):1651-1662. doi: 10.1007/s10792-018-0938-7. Epub 2018 May 2. Erratum in: Int Ophthalmol. 2019 Jun 6;: PMID: 29721842.
  5. Michelessi M, Lindsley K. Peripheral iridotomy for pigmentary glaucoma. Cochrane Database Syst Rev. 2016 Feb 12;2(2):CD005655. doi: 10.1002/14651858.CD005655.pub2. PMID: 26871761; PMCID: PMC5032906.
  6. Ritch R, Liebmann J, Robin A, Pollack IP, Harrison R, Levene RZ, Hagadus J. Argon laser trabeculoplasty in pigmentary glaucoma. Ophthalmology. 1993 Jun;100(6):909-13. doi: 10.1016/s0161-6420(93)31555-1. PMID: 8510905.
  7. Shingleton BJ, Richter CU, Dharma SK, Tong L, Bellows AR, Hutchinson BT, Glynn RJ. Long-term efficacy of argon laser trabeculoplasty. A 10-year follow-up study. Ophthalmology. 1993 Sep;100(9):1324-9. doi: 10.1016/s0161-6420(93)31480-6. PMID: 8371919.
  8. Harasymowycz PJ, Papamatheakis DG, Latina M et al.  Selective laser trabeculoplasty (SLT) complicated by intraocular pressure elevation in eyes with heavily pigmented trabecular meshworks.  Am J Ophthalmol 2005; 139: 1110-1113.

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