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Evaluation of circumferential angle closure using iridotrabecular contact index after laser iridotomy by swept‐source optical coherence tomography
Author(s) -
Cho Hyunkyung,
Ahn Dongsub,
Kee Changwon
Publication year - 2017
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/aos.13190
Subject(s) - optical coherence tomography , ophthalmology , glaucoma , anterior chamber angle , intraocular pressure , medicine , iris (biosensor) , contact lens , nuclear medicine , computer security , computer science , biometrics
Abstract Purpose To investigate the quantitative changes of circumferential angle closure after laser iridotomy ( LI ) using the iridotrabecular contact ( ITC ) index by Swept‐Source optical coherence tomography ( OCT ). Methods In this prospective observational study conducted in a hospital setting, 42 eyes of 36 patients (five males, 31 females) who underwent LI were included. The mean age was 65.00 ± 8.13 years old and the diagnosis included primary angle closure ( PAC , 21 eyes), PAC suspect (16 eyes) and PAC glaucoma (five eyes). Optical coherence tomography (OCT) images were obtained pre‐ LI and at 1 week post‐ LI . In each image frame, the scleral spur ( SS ) and the ITC end‐point were marked, from which the ITC index was calculated as a percentage of the angle closure across 360°. Measurements inspected before and after LI included: central anterior chamber depth ( ACD ), anterior chamber volume ( ACV ), lens vault ( LV ), nasal and temporal angle opening distance ( AOD ), angle recess area ( ARA ), trabecular‐iris space area ( TISA ), trabecular‐iris angle ( TIA ) at 500 μ m and 750 μ m from the SS and intraocular pressure ( IOP ). Results The ITC index and IOP decreased significantly after LI from 71.52 ± 26.29 to 35.31 ± 27.19 and from 20.64 ± 12.72 mmHg to 14.02 ± 3.49 mmHg, respectively (p < 0.001 and p < 0.001). Central ACD (1.94 ± 0.31 mm pre‐ LI ) and LV (1.13 ± 0.32 mm pre‐ LI ) did not show a significant change after LI (all p > 0.05), but ACV increased significantly after LI (p < 0.001). Most of the angle parameters except for nasal TIA s increased significantly after LI (all p < 0.05). Conclusion The ITC index from patients with shallow anterior chamber angle showed a significant decrease after LI , but part of the angle closure was not relieved after LI . Other mechanisms besides pupillary block may play a role together in causing angle closure.