Department of Ophthalmology, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, South Korea.
Department of Ophthalmology, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, South Korea.
Ophthalmology. 2017 Jul;124(7):1039-1047. doi: 10.1016/j.ophtha.2017.02.025. Epub 2017 Apr 3.
To classify eyes with primary angle closure (PAC) in terms of the features visualized using anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM).
Retrospective, observational study.
A total of 73 eyes of 73 patients with PAC.
Participants' eyes that had undergone laser peripheral iridotomy (LPI) were imaged using AS-OCT and UBM under the same lighting conditions. Anterior chamber depth, anterior chamber width, iris cross-sectional area, peripheral iris thickness, iris curvature, lens vault (LV), and angle opening distance 500 μm from the scleral spur (SS) were determined using the AS-OCT image; trabecular-ciliary process angle (TCA), trabecular-ciliary process distance (TCPD), and ciliary body (CB) thickness 1 mm posterior to the SS were estimated on the UBM image using ImageJ software (Wayne Rasband, National Institutes of Health, Rockville, MD). Iris insertion, iris angulation, iris convexity, presence of ciliary sulcus, irido-angle contact, and CB orientation assessed on the UBM image were included. Partitioning around the medoids algorithm was used for cluster analysis based on the parameters obtained using AS-OCT and UBM. Axial length and pupil diameter were incorporated into statistical models.
Clinical and anatomic characteristics were compared between the clusters, as classified using the partitioning around medoids algorithm method.
Cluster analysis revealed that 2-group clustering produced the best results. The 2 clusters, which were defined in terms of parameters obtained using AS-OCT and UBM, showed differences in iris curvature (0.16±0.08 vs. 0.11±0.04 mm), TCA (91.0°±13.4° vs. 63.7°±6.2°), TCPD (0.99±0.22 vs. 0.78±0.16 mm), CB orientation (neutral/anterior, 35/13 vs. 0/25), and iris insertion (basal/middle/apical, 37/9/2 vs. 12/11/2). Pre-LPI intraocular pressure (IOP) (18.8±5.4 vs. 16.2±4.5 mmHg; P = 0.037) and percentage of IOP reduction after LPI (22.3%±17.9% vs. 8.3%±19.5%; P < 0.003) showed a significant difference between the 2 clusters.
The most distinct difference between the 2 subgroups in the cluster analysis was TCA, suggesting that the position of the CB is important in subclassifying PAC. By using UBM, clinicians may obtain more clues about the mechanisms of PAC; in turn, they may learn to predict the IOP-lowering effects of LPI.
利用眼前节光学相干断层扫描（AS-OCT）和超声生物显微镜（UBM）观察到的特征对原发性闭角型青光眼（PAC）患者的眼睛进行分类。
回顾性、观察性研究。
73 例 PAC 患者的 73 只眼。
对已行激光周边虹膜切开术（LPI）的患者的眼睛，在相同光照条件下，分别使用 AS-OCT 和 UBM 进行成像。使用 AS-OCT 图像确定前房深度、前房宽度、虹膜横截面积、周边虹膜厚度、虹膜曲率、晶状体穹窿（LV）和巩膜突（SS）处 500μm 的房角开口距离；使用 ImageJ 软件（位于马里兰州罗克维尔的美国国立卫生研究院的 Wayne Rasband）在 UBM 图像上估计小梁睫状体角（TCA）、小梁睫状体距离（TCPD）和 SS 后 1mm 的睫状体厚度。UBM 图像上评估的虹膜插入、虹膜角度、虹膜凸度、睫状沟存在、房角接触和 CB 方位也包括在内。基于 AS-OCT 和 UBM 获得的参数，使用中位数分区算法进行聚类分析。将眼轴长度和瞳孔直径纳入统计模型。
使用中位数分区算法对聚类进行分类后，比较各组间的临床和解剖特征。
聚类分析显示，2 组聚类产生的结果最佳。基于 AS-OCT 和 UBM 参数定义的 2 个聚类在虹膜曲率（0.16±0.08 与 0.11±0.04mm）、TCA（91.0°±13.4°与 63.7°±6.2°）、TCPD（0.99±0.22 与 0.78±0.16mm）、CB 方位（中性/前位，35/13 与 0/25）和虹膜插入（基底部/中部/顶部，37/9/2 与 12/11/2）方面存在差异。LPI 前的眼内压（IOP）（18.8±5.4 与 16.2±4.5mmHg；P=0.037）和 LPI 后 IOP 降低的百分比（22.3%±17.9%与 8.3%±19.5%；P<0.003）在 2 个聚类之间存在显著差异。
聚类分析中 2 个亚组之间最显著的差异是 TCA，这表明 CB 的位置在 PAC 的亚分类中很重要。通过使用 UBM，临床医生可能会获得有关 PAC 发病机制的更多线索；反过来，他们可能会学会预测 LPI 的降眼压效果。
