Quantification of Anterior Chamber Particles Using Anterior Segment Optical Coherence Tomography in Angle-Closure Glaucoma Patients after Laser Iridotomy

Abstract

Purpose: To determine whether the degree of particle density in the anterior chamber can be evaluated objectively and quantitatively by anterior segment optical coherence tomography (AS-OCT) in cases after laser iridotomy (LI). Methods: This was a retrospective observational study. All of the subjects who received LI for angle-closure glaucoma between January 2018 and May 2019 at Kagoshima University Hospital were studied. AS-OCT recordings were made before, immediately after, and one week after LI in 22 eyes of 14 consecutive patients. The anterior chamber particle (ACP) index was defined as the ratio of the number of particles in the anterior chamber to the total area of the anterior chamber. The ACP index was determined by binarization of the AS-OCT images and analysis with the ImageJ program. Results: The mean age of the participants was 75.4 ± 8.9 years, with a range of 61–91 years. The ACP index before the LI was 0.78 ± 0.68, and it was significantly increased to 7.72 ± 2.64 immediately after the LI (paired t-test, p < 0.01). The ACP index returned to the pre-LI density of 0.92 ± 0.48 one week after the LI. Conclusions: We successfully quantified the degree of anterior chamber particles accumulation by analyzing images obtained by AS-OCT. This simple and repeatable technique should be useful because the particles, including inflammatory cells, in the anterior chamber can be evaluated non-invasively and objectively.