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Y. Jiang, D. S. Chang, P. J. Foster, M. He, S. Huang, D. S. Friedman; Immediate Change in Intraocular Pressure after Laser Iridotomy in Primary Angle-closure Suspects: the Zhongshan Angle-closure Prevention Study. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6404.
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To determine the immediate changes of intraocular pressure after laser peripheral iridotomy (LPI) in primary angle closure suspect (PACS) cases in a randomized clinical trial.
Subjects identified as primary angle-closure suspects aged 50-70 years were treated with LPI using YAG only procedure in a randomly selected eye whereas the fellow eyes served as controls. Intraocular pressure (IOP) was measured using Goldmann Applanation Tonometer before and one hour after LPI. Baseline examinations before LPI included refraction, gonioscopy, ultrasound-A scan, van Herick limbal anterior chamber depth scoring, fundus photography, scanning peripheral anterior chamber depth analyzer imaging and dark room prone provocative testing. Total energy used and complications during the procedures were recorded.
A total of 710 subjects participated in this study. The average IOP increased from 15.55±2.73 mmHg before treatment to 17.47± 4.73 mmHg one hour after treatment in the treated eyes, as compared to 15.57±2.67 mmHg to 15.14± 2.63 mmHg in the untreated eyes. The proportion of eyes with an IOP spike (defined as 8 mmHg or greater elevation) was 10% in the treated eyes and only 0.42% in the untreated eyes. The IOP spike was associated with more laser energy used (0.205±0.185J vs. 0.146±0.118J, P<0.001) and bleeding or corneal burn during LPI procedures (42.26% vs. 30.88%, P=0.051). Multivariable linear regression showed that IOP increased 0.45 mmHg with every 0.1J increase in total laser energy used and increased 2.67 mmHg with every 1 mm decrease in central anterior chamber depth (ACD) as compared to pre-LPI mean IOP.
IOP spike after LPI is associated with total laser energy used, bleeding during the procedure and shallower anterior chamber.
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