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

Abstract.

Purpose: Increased numbers of aqueous melanin granules have been reproducibly demonstrated in eyes with pigment dispersion syndrome using the cell count mode of the laser flare-cell meter. It was the aim of this study to measure the exact number of aqueous melanin granules in eyes with pigment dispersion syndrome and pigmentary glaucoma before and after Nd:YAG laser iridotomy. Methods: Nine eyes of seven patients with a clinical diagnosis of primary pigment dispersion syndrome and secondary open-angle glaucoma (mean age 41.1±10.8 years) were included in this study. Aqueous cells were quantified using the cell count mode of the laser flare-cell meter (Kowa FC-1000) before and 30 min after medical pupillary dilation. Measurements were performed before and 15±7 weeks after Nd:YAG laser iridotomy. The main outcome measure was the number of aqueous melanin granules before and after Nd:YAG laser iridotomy. Results: The number (mean and quartiles) of aqueous melanin granules/0.075 µl aqueous humor (normal/dilated pupil) before antiglaucoma treatment was 4.5 (4.0, 7.25)/9.0 (5.0, 13.0) and was significantly reduced after iridotomy [1.5 (0.75, 3.25)/4.0 (1.6, 6.25), P=0.016]. Conclusion: Nd:YAG laser iridotomy results in significant (65%) decrease of aqueous melanin granules in eyes with primary pigment dispersion syndrome. This finding appears to confirm the concept of reverse pupillary block in primary pigment dispersion syndrome and may indicate that laser iridotomy is a useful treatment option in this condition.