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Tin Aung, Raghavan Lavanya, Rajesh S. Kumar, Mingguang He, Mani Baskaran; Quantitative Changes In Anterior Segment Morphology After Laser Peripheral Iridotomy Using Anterior Segment Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3065.
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© ARVO (1962-2015); The Authors (2016-present)
Recent studies using anterior segment optical coherence tomography (ASOCT) have identified novel parameters associated with angle closure, such as anterior chamber area (ACA) and volume (ACV); anterior chamber width (ACW); lens vault (LV) and iris thickness, area and curvature. The aim of this study was to quantify changes in these parameters using ASOCT, in a cohort of primary angle closure suspects (PACS) after laser peripheral iridotomy (LPI).
In this prospective study, primary angle closure suspects > 50 years of age underwent LPI. ASOCT images (Visante, Carl Zeiss Meditec, Dublin, CA) from 176 subjects were analyzed quantitatively using customized software, prior to and 1 week after LPI.
The mean age of the 176 participants was 63.0 ± 7.3 years, and the majority of the subjects were Chinese (95.5%) and women (76.7%). After LPI, the angle width opened significantly with increase in mean angle opening distance [AOD 500, 0.11 vs 0.18 mm, p< 0.001), trabecular iris surface area (TISA500, 0.06 vs 0.08 mm², p< 0.001) and angle recess area (ARA, 0.12 vs 0.17 mm², p< 0.001). Mean ACA (14.9 vs 16.0 mm², p< 0.001) and ACV (91.6 vs 103.0 mm³, p< 0.001) increased significantly after LPI, but there was no change in ACW (11.21 vs 11.24 mm, p = 0.3), anterior chamber depth (2.16 vs 2.17 mm, p = 0.16) or LV (783.6 vs 788.6µm, p = 0.72). Mean iris curvature reduced (0.375 vs 0.180 mm, p< 0.001) after LPI, but there was no significant change in iris thickness or area.
This study confirms that LPI results in a significant increase in the angle width in subjects with narrow angles. ACA and ACV increased after LPI but there was no change in ACD, ACW, LV or iris thickness and area. The increase in ACA/ACV was due to decreased iris curvature after LPI.
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