QUANTIFICATION OF AQUEOUS MELANIN GRANULES IN PRIMARY PIGMENT DISPERSION SYNDROME

PURPOSE: Aqueous melanin granules are essential in the pathogenesis of pigment dispersion syndrome and pigmentary glaucoma. We quantified aq ueous melanin granules with the laser flare-cell meter in patients wit h pigment dispersion syndrome, assessed the measurement reproducibilit y, and correlated the numbers with clinical findings. METHODS: Aqueous melanin granules were counted by means of the cell count mode of the laser flare cell meter (KOWA FC-1000; Kowa, Tokyo, Japan) in 42 eyes o f 21 patients with primary pigment dispersion syndrome under three con ditions (undilated pupils, dilated pupils, after exercise). The reprod ucibility of the measurements was determined with the intraclass corre lation coefficient. A control group of 40 age- and sex-matched eyes wa s also examined after pupillary dilation. The results were correlated with biomicroscopic findings in eyes with pigment dispersion syndrome (retrocorneal Krukenberg spindle, iris transillumination, pigmentation of trabecular meshwork). RESULTS: Numerous aqueous melanin granules w ere detected in eyes with pigment dispersionsyndrome (mean, 2.9 +/- 3. 7 granules/0.075 mm(3)) but only small numbers were counted in normal eyes (0.2 +/- 0.3, P < .001). Medical pupil dilation caused an additio nal increase of aqueous melanin granules in pigment dispersion syndrom e (6.3 +/- 5.3, P < .001), but not undilated exercise (climbing stairs ) (2.9 +/- 3.7, P > .5). The reproducibility of the measurements was v ery high (intraclass coefficient >0.92). The number of melanin granule s correlated with the degree of Krukenberg spindle (r = .61, P = .004) and with iris transillumination (r = .69, P = .001). CONCLUSIONS: Qua ntification of aqueous melanin granules yields reproducible results an d shows increased numbers in pigment dispersion syndrome, especially a fter pupillary dilation. Aqueous melanin granule quantification may be useful for evaluating eyes with pigment dispersion syndrome and for a ssessing treatment effects. (C) 1998 by Elsevier Science Inc. All righ ts reserved.