Singapore Eye Research Institute, Singapore & Singapore National Eye Centre, Singapore, Singapore.
Graefes Arch Clin Exp Ophthalmol. 2012 Sep;250(9):1353-9. doi: 10.1007/s00417-012-1934-7. Epub 2012 Jan 31.
To evaluate the speed of pupil constriction (SPC) in response to a standardized change in illumination from dark to light using anterior segment optical coherence tomography (AS-OCT) in eyes with closed angles, compared to those with open angles.
This was a prospective, comparative, observational study. Study subjects with primary angle-closure glaucoma (PACG) and/or primary angle-closure (PAC) were recruited along with a group of normal as controls. Videos of iris and anterior segment changes in response to illumination were captured with real-time video recording from AS-OCT and analysed frame by frame, beginning from a dilated to a constricted pupil. Customized software was used to measure speed of iris constriction, anterior chamber depth (ACD), anterior chamber width (ACW), iris thickness, and pupil diameter (PD). SPC was defined as the rate of pupil diameter change in response to illumination.
One hundred and sixty three Chinese subjects were recruited in this study. A total of 137 of 163 eligible videos (82.5%) were available for analysis, comprising 87 subjects with closed angles (all had undergone laser peripheral iridotomies before) and 50 with open angles. SPC was less in eyes with closed angles (1.22 mm/sec vs 1.56 mm/sec, p<0.001), after adjusting for age and ACW, and was positively correlated with axial length, ACD, anterior chamber angle status, PD in the dark, and iris thickness in the dark, (all r>0.2, all p<0.05). In multivariate analysis, SPC was independently associated with anterior chamber angle status (closed angle vs open angle) (β=0.276, p=0.016) and PD in dark (β= 0.129, p=0.009), after adjusting for age, ACW, ACD, iris thickness and vertical cup-to-disc ratio.
Compared to those with open angles, eyes with closed angles in Chinese subjects have slower speed of pupil constriction in response to dark-light change, even after adjusting for biometric factors associated with angle closure. The results suggest that differences in irido-pupillary dynamics may play a role in the pathogenesis of angle closure.
使用眼前节光学相干断层扫描（AS-OCT）评估在黑暗到光明的光照变化下瞳孔收缩（SPC）的速度，与开放角相比，在闭角中。
这是一项前瞻性、对照、观察性研究。研究对象为原发性闭角型青光眼（PACG）和/或原发性闭角（PAC）患者，并招募了一组正常患者作为对照组。使用 AS-OCT 进行实时视频记录，捕获虹膜和眼前节对光照的变化视频，并逐帧分析，从散瞳到缩瞳。使用定制软件测量虹膜收缩速度、前房深度（ACD）、前房宽度（ACW）、虹膜厚度和瞳孔直径（PD）。SPC 定义为瞳孔直径对光照的变化率。
本研究共招募了 163 名中国受试者。共有 163 名合格视频中的 137 名（82.5%）可用于分析，包括 87 名闭角患者（所有患者均在接受激光周边虹膜切开术之前）和 50 名开角患者。调整年龄和 ACW 后，闭角眼的 SPC 较低（1.22mm/sec 与 1.56mm/sec，p<0.001），与眼轴长度、ACD、前房角状态、黑暗中的 PD 和黑暗中的虹膜厚度呈正相关（所有 r>0.2，所有 p<0.05）。在多元分析中，SPC 与前房角状态（闭角与开角）独立相关（β=0.276，p=0.016）和黑暗中的 PD（β=0.129，p=0.009），调整年龄、ACW、ACD、虹膜厚度和垂直杯盘比后。
与开角相比，中国患者的闭角眼中，在黑暗到明亮的光变化下瞳孔收缩的速度较慢，即使在调整与闭角相关的生物测量因素后也是如此。结果表明，虹膜瞳孔动力学的差异可能在闭角发病机制中起作用。
