Impact of YAG Laser Peripheral Iridotomy on Anterior Segment in Primary Angle Closure using Optical Coherence Tomography and Corneal Tomography

Background: Irreversible visual morbidity is primarily caused by primary angle-closure suspect (PACS) and primary angle closure (PAC), which are important stages in the angle-closure illness spectrum. The conventional treatment for pupillary block is laser peripheral iridotomy (LPI), however its quantitative effect on anterior segment parameters is still unclear. Scheimpflug corneal tomography and anterior segment optical coherence tomography (AS-OCT) offer reliable, repeatable measurements that aid in assessing structural changes after LPI.Methods: A cross-sectional study was conducted on 30 eyes diagnosed as PACS or PAC at Zagazig University Hospital. All cases underwent comprehensive ophthalmic evaluation including visual acuity, slit-lamp examination, Goldmann applanation tonometry, gonioscopy using Shaffer grading, visual field testing, AS-OCT imaging, and Sirius corneal tomography. LPI was performed using Nd:YAG laser, and patients were followed. AS-OCT and tomography measurements were repeated at 1 and 3 months.Results: LPI produced a significant and progressive widening of anterior chamber angle parameters in both PACS and PAC patients. Measurements of ACA and AOD500, AOD 750 and ACV showed substantial increases at 1 and 3 months compared with baseline. PACS patients demonstrated significantly greater improvements than PAC in several nasal and superior quadrants. No major complications were observed other than transient postoperative IOP elevation in a few cases, which responded to medical therapy. Conclusion: LPI results in marked anatomical improvement of anterior chamber angle in both PACS and PAC eyes, as demonstrated by AS-OCT and Scheimpflug tomography. These imaging modalities provide reliable quantitative assessment of treatment response.