Quantification of aqueous melanin granules, intraocular pressure and glaucomatous damage in primary pigment dispersion syndrome

Objective: Aqueous melanin granules may be accurately quantified with the l aser flare-cell meter and have been demonstrated to be increased in primary pigment dispersion syndrome (PDS). It was the aim of this study to correla te intraocular pressure, glaucomatous damage of the optic nerve head, and v isual field defects with the number of aqueous melanin granules in PDS. Design: Cross-sectional study. Participants: Thirty-nine eyes of 21 patients with PDS and either ocular hy pertension or pigmentary glaucoma. Main Outcome Measures: A 24-hour intraocular pressure (IOP) profile, automa ted perimetry (Octopus G1), and analysis of photostereographs and HRT (Heid elberg Retina Tomograph) images of the optic disc were performed. Aqueous m elanin granules were quantified using the cell count mode of the laser fare -cell meter (KOWA FC-1000) with undilated and dilated pupils. Granule count s were correlated with maximum and mean IOP, maximum range (amplitude) of I OP, mean defect of automated perimetry (G1-program), and damage to the opti c disc was measured with the HRT. Results: The number of aqueous melanin granules showed a strong correlation with maximum IOP in both undilated (r = 0.72, P < 0.001) and dilated eyes (r = 0,5, P = 0.02). A marginal correlation was found with the IOP range (r = 0.43, P = 0.04) and the mean defect of automated perimetry (r = 0.41, P = 0.06) in undilated eyes. The mean IOP and HRT measurements of the optic d isc (area, volume of the neuroretinal rim, third moment in contour) showed no statistically significant correlation with the number of aqueous melanin granules (r < 0,4, P > 0.2). Conclusions: A larger number of aqueous melanin granules is strongly associ ated with high IOP and also with visual field loss, providing additional ev idence of the relation between aqueous melanin dispersion and development o f pigmentary glaucoma. Quantification of aqueous melanin granules with the laser flare-cell meter might be useful for evaluation of treatment effects, including laser iridotomy, in patients with PDS. (C) 2000 by the American Academy of Ophthalmology.