Department of Ophthalmology, Edouard Herriot Hospital, Lyon 1 University, Lyon, France.
Ophthalmology. 2010 Jan;117(1):3-10. doi: 10.1016/j.ophtha.2009.10.030. Epub 2009 Nov 17.
To describe a method using anterior segment optical coherence tomography (AS OCT) for estimating iris volume. To quantify changes in iris volume induced by pharmacologic mydriasis in narrow-angle eyes predisposed to angle-closure compared with normal open-angle eyes.
Cross-sectional study.
Thirty fellow eyes of 30 patients who had an episode of primary acute angle-closure and 30 eyes of 30 normal age- and gender-matched subjects with open angles. All fellow eyes had a patent laser peripheral iridotomy.
Iris volume and all biometric measurements were performed before and after instillation of 1% tropicamide and at least 1 week later 10% phenylephrine. Iris volume was estimated using AS OCT radial sections of the iris and a customized image-processing software.
Iris volume, pupil diameter, angle configuration including angle opening distance at 500 mum (AOD 500) and trabecular-iris space at 500 mum (TISA 500), AS OCT anterior chamber depth, and A-scan ultrasonography axial length before and after pupil dilation.
Iris volumes measured before dilation of the pupil were 44.94+/-2.1 mm(3) and 44.29+/-3.9 mm(3) in the fellow eyes and open-angle eyes, respectively, which was not significantly different (P>0.1). Thirty minutes after instillation of 1% tropicamide, mean iris volume increased significantly in the fellow eyes (from 44.94+/-2.1 mm(3) to 49.92+/-2.9 mm(3); P<0.01), whereas it decreased significantly in the open-angle eyes (from 44.29+/-3.9 mm(3) to 37.88+/-2.2 mm(3); P<0.01). Similar changes were observed after instillation of 10% phenylephrine. Based on multivariate analysis, significant predictors of increase in iris volume after pupil dilation were eyes predisposed to angle-closure compared with open-angle eyes (P = 0.008), larger pupil diameter (P = 0.02), and brown eyes (P = 0.01). Relative iris volume increase was correlated significantly with AOD 500 and TISA 500 relative decrease in the narrow-angle group (P<0.05).
The iris volume may be estimated with AS OCT. The iris volume increases after pupil dilation in narrow-angle eyes predisposed to acute angle closure. In those patients, this biometric change is associated with a narrowing of the angle despite a patent laser peripheral iridotomy.
FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
描述一种使用前节光学相干断层扫描（AS OCT）来估计虹膜体积的方法。定量比较窄角眼的药物性散瞳前后虹膜体积的变化，这些窄角眼易发生闭角型青光眼，而正常开角眼则作为对照。
横断面研究。
30 例原发性急性闭角型青光眼发作患者的 30 只对侧眼，以及 30 例年龄和性别匹配的正常开角眼患者的 30 只眼。所有对侧眼均有激光周边虹膜切开术。
在滴入 1%阿托品前后以及至少 1 周后滴入 10%苯肾上腺素后，使用 AS OCT 虹膜的放射状切片和定制的图像处理软件测量虹膜体积和所有生物测量值。
瞳孔扩张前后的虹膜体积、瞳孔直径、角度配置（包括 500μm 处的房角开口距离（AOD 500）和 500μm 处的小梁虹膜空间（TISA 500）、AS OCT 前房深度和 A 扫描超声轴向长度。
散瞳前，对侧眼和开角眼的虹膜体积分别为 44.94+/-2.1mm(3)和 44.29+/-3.9mm(3)，差异无统计学意义（P>0.1）。滴入 1%阿托品 30 分钟后，对侧眼的平均虹膜体积显著增加（从 44.94+/-2.1mm(3)增加至 49.92+/-2.9mm(3)；P<0.01），而开角眼的虹膜体积显著减少（从 44.29+/-3.9mm(3)减少至 37.88+/-2.2mm(3)；P<0.01）。滴入 10%苯肾上腺素后也观察到类似的变化。多变量分析显示，瞳孔扩张后虹膜体积增加的显著预测因素是与开角眼相比，易发生闭角型青光眼的眼（P=0.008）、更大的瞳孔直径（P=0.02）和棕色眼睛（P=0.01）。在窄角组中，相对虹膜体积增加与 AOD 500 和 TISA 500 的相对减少显著相关（P<0.05）。
AS OCT 可用于估计虹膜体积。窄角眼易发生急性闭角型青光眼的患者，散瞳后虹膜体积增加。在这些患者中，尽管有激光周边虹膜切开术，但这种生物测量变化与角度变窄有关。
作者在本文讨论的材料中没有任何专有或商业利益。
