Optometry and Vision Department, Complutense University of Madrid, Madrid, Spain.
Ophthalmology Service, San Carlos Clinical Hospital of Madrid, Madrid, Spain.
Ophthalmic Physiol Opt. 2022 Jan;42(1):133-139. doi: 10.1111/opo.12897. Epub 2021 Oct 8.
The disc-fovea angle (DFA) is used as a relevant indicator of ocular torsion change in cyclovertical strabismus. However, interpretation of the variation in time must differentiate whether a real change has occurred or if the disparity is due to random measurement error. The aim of the study was to obtain the minimal detectable change (MDC) of the DFA. It represents the minimal variation between two measurements that may be considered a real ocular torsion change.
A prospective cross-sectional study was conducted in San Carlos Clinical Hospital of Madrid, Spain. Sixty healthy right eyes from 60 patients (31 men and 29 women) were recruited. Three digital fundus photographs were obtained, and between measurements, the patient moved their head away from the head support and then returned. Two observers quantified the DFA with software designed with MATLAB. Test-retest and interrater reliability were calculated.
Mean participant age was 56.1 years (SD 16.6, range 25-85). Mean DFA was 8.1° (SD 3.5, range 1.3-18.5). Test-retest reliability for Observer 1 (Ob1), Observer 2 (Ob2) and interrater reliability were excellent (ICC 0.80, 0.83 and 0.95, respectively). Precision was 2.9° (Ob1) and 3.0° (Ob2), and the MDC was 4.1° (Ob1) and 4.2° (Ob2). Bland-Altman analysis revealed an absence of bias and a homoscedastic distribution of the differences.
The MDC of the DFA in fundus photography was 4°, which represents the minimal change that may be considered a real change in ocular torsion. This result may improve the interpretation of ocular torsion changes in surgery and clinical scenarios.
盘-黄斑角（DFA）可作为斜肌垂直分离性斜视眼扭转变化的相关指标。然而，对时间变化的解释必须区分是否发生了真正的变化，或者差异是否是由于随机测量误差造成的。本研究的目的是获得 DFA 的最小可检测变化（MDC）。它代表两次测量之间可能被认为是真实眼扭转变化的最小变化。
在西班牙马德里圣卡洛斯临床医院进行了一项前瞻性的横断面研究。共招募了 60 名健康的右眼球，来自 60 名患者（31 名男性和 29 名女性）。获得了三张眼底数字照片，在测量之间，患者将头从头托上移开，然后再放回。两名观察者使用 MATLAB 设计的软件定量测量 DFA。计算了测试-重测和观察者间可靠性。
参与者的平均年龄为 56.1 岁（标准差 16.6，范围 25-85）。平均 DFA 为 8.1°（标准差 3.5，范围 1.3-18.5）。观察者 1（Ob1）、观察者 2（Ob2）和观察者间可靠性的测试-重测可靠性均为优（ICC 分别为 0.80、0.83 和 0.95）。精度为 2.9°（Ob1）和 3.0°（Ob2），MDC 为 4.1°（Ob1）和 4.2°（Ob2）。Bland-Altman 分析显示不存在偏倚，差异的分布具有同方差性。
眼底照相中 DFA 的 MDC 为 4°，这代表了可能被认为是眼扭转真实变化的最小变化。这一结果可能会改善手术和临床情况下对眼扭转变化的解释。
