Effect of neodymium : YAG laser iridotomy on number of aqueous melanin granules in primary pigment dispersion syndrome

Purpose: Increased numbers of aqueous melanin granules have been reproducib ly demonstrated in eyes with pigment dispersion syndrome using the cell cou nt mode of the laser flare-cell meter. It was the aim of this study to meas ure the exact number of aqueous melanin granules in eyes with pigment dispe rsion syndrome and pigmentary glaucoma before and after Nd:YAG laser iridot omy. Methods: Nine eyes of seven patients with a clinical diagnosis of prim ary pigment dispersion syndrome and secondary open-angle glaucoma (mean acr e, 41.1 +/- 10.8 years) were included in this study. Aqueous cells were qua ntified using the cell count mode of the laser flare-cell meter (Kowa FC-10 00) before and 30 min after medical pupillary dilation. Measurements were p erformed before and 15+/-7 weeks after Nd:YAG laser iridotomy. The main out come measure was the number of aqueous melanin granules before and after Nd :YAG laser iridotomy. Results: The number (mean and quartiles) of aqueous m elanin granules/0.075 mul aqueous humor (normal/dilated pupil) before antig laucoma treatment was 4.5 (4.0, 7.25)/ 9.0 (5.0, 13.0) and was significantl y reduced after iridotomy [1.5 (0.75, 3.25)/4.0 (1.6, 6.25), P=0.016]. Conc lusion: Nd:YAG laser iridotomy results in significant (65%) decrease of aqu eous melanin granules in eyes with primary pigment dispersion syndrome. Thi s finding appears to confirm the concept of reverse pupillary block in prim ary pigment dispersion syndrome and may indicate that laser iridotomy is a useful treatment option in this condition.