Clinical signs of the pigment dispersion syndrome in blacks

The pigment dispersion syndrome (PDS) is considered rare in blacks, and minimal literature exists concerning the condition in this patient population. The diagnosis of PDS in blacks may present unique challenges because some of the typical clinical signs that are present in whites, including iris transillumination defects, posterior iris bowing, and noticeable anterior iris stromal pigment dusting, may not occur as commonly. Diagnosis can be particularly difficult when neither these signs nor significant corneal endothelial pigmentation exists. Although zonular and peripheral lens pigment has been found to be consistently present in whites with PDS, attention has not been given to this as a potentially important diagnostic sign in blacks.

From among a primary care population, we identified and studied 7 patients (13 eyes) who exhibited moderate to heavy trabecular meshwork (TM) pigmentation, as well as zonule and/or peripheral lens pigmentation. Patients were identified during routine clinical care provided by one of the authors, as well as from notification by other practitioners. All patients received complete eye examination and other signs of PDS were looked for.

Four males and 3 females were identified, their average age being 37 years (range = 15 to 51) at the time of their initial identification. All but one patient was myopic (average approximately -2.50 D spherical equivalent). Iris transillumination defects were present in only one eye of one patient, and no eyes showed overt posterior iris bowing, although the iris contours were usually flat and the anterior chambers appeared relatively deep. Corneal endothelial pigmentation was frequently barely detectable and could not be relied on as a predictor of trabecular meshwork or lenticular pigmentation. Glaucoma, or a suspicion of glaucoma due to increased intraocular pressure (IOP) or cupping, was common among the group. Using heavy TM pigmentation as well as any degree of zonular and/or peripheral lenticular pigmentation as a criteria for the diagnosis of PDS, we calculated the prevalence of PDS among blacks in a nonreferred primary care population (> age 7) to be at least 15 cases per 10,000.

More investigation is needed to study the clinical presentation of PDS in blacks because it may be substantially different than in whites. Zonular and peripheral lenticular pigmentation may be a particularly useful diagnostic sign of PDS in blacks, especially in those cases where other traditional signs, including iris transillumination defects, pronounced corneal endothelial pigmentation, posterior iris bowing, and visible anterior iris stromal pigment dusting, are absent. The "classic" variety of PDS may be more common among blacks than previously recognized.