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R. Sasikumar, M. Baskaran, P. T. K. Chew, H.-T. Wong, D. Friedman, P. J. Foster, T. Aung; Prophylactic Laser Iridotomy in Eyes With Narrow Drainage Angles: A Randomized Controlled Trial. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3985.
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To assess the short-term effect of laser iridotomy (LI) on anterior chamber configuration in primary angle closure suspects (PACS).
As part of a prospective randomized controlled trial, subjects over the age of 50 and diagnosed as PACS in both eyes underwent prophylactic sequential LI in one eye, while the fellow eye served as a control. PACS was defined as an eye where the posterior trabecular meshwork was not visible for at least 180º on non-indentation gonioscopy, intraocular pressure ≤ 21 mm Hg, no peripheral anterior synechiae and no disc or field changes. All subjects underwent ultrasound A-scan biometry (central anterior chamber depth or ACD), modified van Herick (vH) grading for limbal anterior chamber depth and gonioscopy before and one week after LI. Modified vH grading was done as a percentage fraction of the thickness of the cornea in the following seven categories: 0%, 5%, 15%, 25%, 40%, 75%, and >100%. Gonioscopy was performed using 2 and 4 mirror gonioscopes using standardized testing conditions; the angles were graded using Shaffer’s criteria and angle width was averaged for analysis.
150 eyes (150 subjects) underwent LI in one randomly selected eye. The mean age was 63.14 ± 5.53 years (50-84 years). Majority of the subjects were Chinese (88%) and females (76%). There was no significant difference between baseline data for ACD (paired t test, p= 0.272), vH grading (McNemar test, p= 0.755) and mean angle width (paired t test, p= 0.756) between eyes that underwent LI and fellow eyes. The vH grading increased significantly after LI (p<0.001). The mean ACD changed from 2.69 ± 0.42 mm to 2.81 ± 0.53 mm after LI (p=0.051). The mean angle grading increased significantly from 0.59 ± 0.54 to 1.83 ± 0.89 (p<0.0001) after LI. There was no significant change at week1 in vH (p=0.15), ACD (p=0.83) or angle width (p=0.06) in fellow eyes that did not undergo LI.
In this short-term follow-up of a cohort of Asian PACS eyes, sequential LPI widened the angle significantly and there was an increase in peripheral chamber depth.
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