Kaye S B, Siddiqui A, Ward A, Noonan C, Fisher A C, Green J R, Brown M C, Wareing P A, Watt P
Royal Liverpool Children's NHS Trust, Ophthalmology Department, Liverpool, United Kingdom.
Optom Vis Sci. 1999 Nov;76(11):770-82. doi: 10.1097/00006324-199911000-00026.
Measurement of stereoacuity at varying distances, by real or simulated depth stereoacuity tests, is helpful in the evaluation of patients with binocular imbalance or strabismus. Although the cue of binocular disparity underpins stereoacuity tests, there may be variable amounts of other binocular and monocular cues inherent in a stereoacuity test. In such circumstances, a combined monocular and binocular threshold of depth discrimination may be measured--stereoacuity conventionally referring to the situation where binocular disparity giving rise to retinal disparity is the only cue present. A child-friendly variable distance stereoacuity test (VDS) was developed, with a method for determining the binocular depth threshold from the combined monocular and binocular threshold of depth of discrimination (CT).
Subjects with normal binocular function, reduced binocular function, and apparently absent binocularity were included. To measure the threshold of depth discrimination, subjects were required by means of a hand control to align two electronically controlled spheres at viewing distances of 1, 3, and 6m. Stereoacuity was also measured using the TNO, Frisby, and Titmus stereoacuity tests. BTs were calculated according to the function BT= arctan (1/tan alphaC - 1/tan alphaM)(-1), where alphaC and alphaM are the angles subtended at the nodal points by objects situated at the monocular threshold (alphaM) and the combined monocular-binocular threshold (alphaC) of discrimination.
In subjects with good binocularity, BTs were similar to their combined thresholds, whereas subjects with reduced and apparently absent binocularity had binocular thresholds 4 and 10 times higher than their combined thresholds (CT). The VDS binocular thresholds showed significantly higher correlation and agreement with the TNO test and the binocular thresholds of the Frisby and Titmus tests, than the corresponding combined thresholds (p = 0.0019).
The VDS was found to be an easy to use real depth (distance) stereoacuity test. The method described for calculating the BT provides one simple nonlinear solution for determining the respective contributions of binocular and monocular (MT) depth discrimination to the combined depth threshold.
通过真实或模拟深度立体视锐度测试在不同距离测量立体视锐度，有助于评估双眼不平衡或斜视患者。尽管双眼视差线索是立体视锐度测试的基础，但立体视锐度测试中可能存在数量可变的其他双眼和单眼线索。在这种情况下，可以测量深度辨别力的单眼和双眼联合阈值——传统上，立体视锐度是指引起视网膜视差的双眼视差是唯一存在的线索的情况。开发了一种适合儿童的可变距离立体视锐度测试（VDS），并提出了一种从深度辨别力联合单眼和双眼阈值（CT）确定双眼深度阈值的方法。
纳入双眼功能正常、双眼功能降低以及明显无双眼视的受试者。为了测量深度辨别力阈值，受试者需要通过手动控制将两个电子控制的球体在1米、3米和6米的观察距离处对齐。还使用TNO、Frisby和Titmus立体视锐度测试测量立体视锐度。根据公式BT = arctan (1/tan αC - 1/tan αM)(-1)计算BT，其中αC和αM分别是位于单眼阈值（αM）和深度辨别力联合单眼-双眼阈值（αC）处的物体在节点处所张的角度。
在双眼视功能良好的受试者中，BT与他们的联合阈值相似，而双眼视功能降低和明显无双眼视的受试者的双眼阈值分别比他们的联合阈值（CT）高4倍和10倍。与相应的联合阈值相比，VDS双眼阈值与TNO测试以及Frisby和Titmus测试的双眼阈值显示出显著更高的相关性和一致性（p = 0.0019）。
发现VDS是一种易于使用的真实深度（距离）立体视锐度测试。所描述的计算BT的方法为确定双眼和单眼（MT）深度辨别力对联合深度阈值的各自贡献提供了一种简单的非线性解决方案。
