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V. T. Koh, R. S. Kumar, K. Y. Lee, D. T. Quek, F. T. Oen, L. S. MohanRam, T. Aung; Prevalence of Plateau Iris in Primary Angle Closure Glaucoma. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5102. doi: https://doi.org/.
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To determine the prevalence of plateau iris in a cohort of primary angle closure glaucoma (PACG) subjects using ultrasound biomicroscopy (UBM).
In this cross-sectional observational study, PACG subjects over the age of 40 years with previous laser peripheral iridotomy (LPI) were enrolled. PACG was defined as the presence of glaucomatous optic neuropathy (defined as loss of neuroretinal rim with a vertical cup: disc ratio of ≥ 0.7) with compatible visual field loss, in association with a closed angle (presence of at least 180 degrees of angle in which the trabecular meshwork was not visible on gonioscopy), and raised IOP and/or PAS. UBM was performed in all 4 quadrants of each eye and UBM images were qualitatively assessed in right eyes using standardized criteria. Plateau iris in a quadrant was defined by the presence of an anteriorly directed ciliary body, an absent ciliary sulcus, a steep iris root from its point of insertion followed by a downward angulation from the corneoscleral wall, presence of a central flat iris plane and irido-angle contact. At least 2 quadrants had to fulfill the above criteria for an eye to be classified as plateau iris.
80 PACG patients were enrolled. The mean age was 66.8 ± 7.6 (range 45-90) years; the majority of subjects were Chinese (95%) and female (61.3%). Based on standardized UBM criteria, plateau iris was found in 27 of 80 (33.7%) PACG eyes. Quadrantwise analysis showed that 12 of 80 (15.0%) eyes had plateau iris in 2 quadrants, 7 (8.6%) in 3 quadrants, and 8 (10.0%) in all 4 quadrants.
Using strict and standardized UBM criteria, a third of PACG eyes with previous LPI were classified as plateau iris. Prospective longitudinal studies are required to determine the clinical significance of this finding in the long-term management of PACG.
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