Iridolenticular Contact Decreases Following Laser Iridotomy for Pigment Dispersion Syndrome

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Abstract
A PERIPHERAL iris concavity facilitates iridozonular contact and pigment liberation in pigment dispersion syndrome and pigmentary glaucoma. In reverse pupillary block, this concavity is due to greater aqueous humor volume or pressure in the anterior chamber relative to the posterior chamber, which pushes the iris posteriorly.1 How and why reverse pupillary block develops, however, remains poorly elucidated. It is believed analogous to relative (forward) pupillary block, which leads to angle-closure glaucoma. Like pupillary block, is relieved by laser iridotomy, which produces a planar iris configuration in both disorders. In relative pupillary block, the loss of iris convexity after iridotomy is accompanied by increased iris-lens contact, as the central iris falls backward with the elimination of the aqueous pressure in the posterior chamber.2 If the reverse pupillary block in pigment dispersion syndrome is analogous to this, then iris-lens contact should decrease and the central iris should move anteriorly with the elimination of the aqueous pressure gradient from the anterior to the posterior chamber. To test this hypothesis, we used ultrasound biomicroscopy to evaluate the effect of laser iridotomy on angle width and iridolenticular contact distance in eyes with pigment dispersion syndrome.