Pigment dispersion syndrome
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Pigment Dispersion Syndrome
Pigment Dispersion Syndrome Dr. Aditi SinghDescribed by : Sugar and Brown 1949Pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) :
two successive stages of the same disease process characterized by
disruption of the iris pigment epithelium
and deposition of the dispersed pigment granules throughout the anterior segment
Experiences blurry vision or eye pain after exercisePathophysiologyConcave iris contour that allows apposition of its posterior surface to the zonular bundles.
Friction between zonules and the peripheral iris - cause of the pigment liberation.
Reverse pupillary block mechanism may exist : flap valve,
Accumulation of pigment granules in the intertrabecular meshwork
Increases resistance of aqueous egress elevating IOP
Exercise (jogging, playing basketball, and bouncing during dancing) can cause the release of pigment as a result of pupillary movement.
Pharmacologic pupillary dilation - may result in significant pigment liberation into the anterior chamber.
This pigment liberation may be accompanied by IOP increase.Clinical features:Myopes, young males,caucacians, positive family history
Cornea: Corneal endothelial pigment appears as a central, vertical, brown band (Krukenberg spindle)
Iris: Loss of iris pigment appears as a midperipheral, radial, slit-like pattern of transillumination defects.Difficult to appreciate in dark iris.
Lens / Zonules : Interrupted lines on the posterior peripheral surface of the lens Zentamayer ring or Scheies stripe.
Angle: Wide open. Heavy dark brown to black pigmentation. Homogenous . Prominent inferiorly.
The iris is inserted posteriorly into the ciliary body, configuration : concave
Posterior segment:lattice degeneration - 20% of patients
retinal breaks- 11.7%
rhegmatogenous retinal detachmentsrequiring surgery may occur in 3.3%
Optic nerve examination:Size , PPA, RNFL defect, disc hges, NRR thinning
Temporal Evolution of PDSConversion of PDS to PG slow and may take years
slow spontaneous resolution irreversible damage to angle
transillumination defects may disappear,
the IOP may return to normal,
the trabecular meshwork pigmentation may decrease. Pigment reversal sign ( burned out )Differential DiagnosisDisorders causing anterior segment pigment dispersion : exfoliation syndrome (XFS), diabetes, herpetic eye disease, iris pigment epithelitis,radiation, trauma, iris pigment epithelial cysts, ciliarybody cysts, iris nevus, and melanoma or melanocytoma ofthe anterior and posterior segment.Features Pseudoexfoliation
syndrome Pigment dispersion syndromeTransillumination defects Peripupillary Radial mid peripheral TM pigmentation Patchy homogenousAge group > 60 yrs ( older) 20- 30 yrs (younger)whitish granular deposits
Present AbsentTreatment The treatment of PDS/PG is aimed at reversing the iris concavity, preventing pigment release, and therefore lowering IOP.
Miotics: reverses the iris concavity and eliminates iridozonular contact.
Tension over the scleral spur, miotics increase aqueous outflow through the trabecular meshwork.
Peripheral retina should be examined carefullyProstaglandin analogues: Increasing uveoscleral outflow.
Agents that lower IOP by reducing aqueous production hypothetically
may diminish the rate of clearance of the pigment from the trabecular meshwork, possibly exacerbating the disease process.
these agents may inhibit relative pupillary block, which is therapeutic in PDS.Laser iridotomyEqualizes pressures between the anterior and posterior chambers, Flattens the iris, Eliminates iridozonular contact, and Occasionally decreases further liberation of pigment
Proper patient selection.
Ideally, patients should still be in the pigment liberation stage.
In young patients with iris concavity, active release of pigment and ocular hypertension, LI may be of benefit for years.
Argon laser trabeculoplasty and selective laser trabeculoplastyAlternative treatments to lower IOP, mostly in young pigmentary glaucoma patients.
The success rate of argon laser trabeculoplasty (ALT) in PG is greater in younger patients than in older ones and decreases with ageTrabeculectomy :
Not responding to medical / laser therapy.
MMC to be used in lower concentration for lesser time.
Outcomes comparable /better than of POAG