Mohd Radzi Hilmi, Khairidzan Mohd Kamal, Mohd Zulfaezal Che Amin, Azrin Esmady Ariffin
Department of Optometry and Vision Science, Kulliyyah of Allied Health Sciences, International Islamic University Malaysia (IIUM), Kuantan, Pahang, Malaysia; Department of Ophthalmology, Kulliyyah of Medicine, International Islamic University Malaysia (IIUM), Kuantan, Pahang, Malaysia.
Department of Ophthalmology, Kulliyyah of Medicine, International Islamic University Malaysia (IIUM), Kuantan, Pahang, Malaysia.
J Optom. 2019 Oct-Dec;12(4):272-277. doi: 10.1016/j.optom.2019.04.001. Epub 2019 May 13.
To describe an objective method to accurately quantify corneo-pterygium total area (CPTA) by utilising image analysis method and to evaluate its association with corneal astigmatism (CA).
120 primary pterygium participants were selected from patients who visited an ophthalmology clinic. We adopted image analysis software in calculating the size of invading pterygium to the cornea. The marking of the calculated area was done manually, and the total area size was measured in pixel. The computed area is defined as the area from the apex of pterygium to the limbal-corneal border. Then, from the pixel, it was transformed into a percentage (%), which represents the CPTA relative to the entire corneal surface area. Intra- and inter-observer reliability testing were performed by repeating the tracing process twice with a different sequence of images at least one (1) month apart. Intraclass correlation (ICC) and scatter plot were used to describe the reliability of measurement.
The overall mean (N=120) of CPTA was 45.26±13.51% (CI: 42.38-48.36). Reliability for region of interest (ROI) demarcation of CPTA were excellent with intra and inter-agreement of 0.995 (95% CI, 0.994-0.998; P<0.001) and 0.994 (95% CI, 0.992-0.997; P<0.001) respectively. The new method was positively associated with corneal astigmatism (P<0.01). This method was able to predict 37% of the variance in CA compared to 21% using standard method.
Image analysis method is useful, reliable and practical in the clinical setting to objectively quantify actual pterygium size, shapes and its effects on the anterior corneal curvature.
描述一种利用图像分析方法准确量化角膜-翼状胬肉总面积（CPTA）的客观方法，并评估其与角膜散光（CA）的相关性。
从眼科门诊就诊的患者中选取120例原发性翼状胬肉患者。我们采用图像分析软件计算翼状胬肉侵入角膜的大小。计算区域的标记通过手动完成，总面积大小以像素为单位进行测量。计算区域定义为从翼状胬肉顶端到角膜缘-角膜边界的区域。然后，从像素值转换为百分比（%），表示CPTA相对于整个角膜表面积的比例。通过至少间隔一（1）个月以不同图像序列重复追踪过程两次，进行观察者内和观察者间可靠性测试。组内相关系数（ICC）和散点图用于描述测量的可靠性。
CPTA的总体平均值（N = 120）为45.26±13.51%（CI：42.38 - 48.36）。CPTA感兴趣区域（ROI）划分的可靠性极佳，观察者内一致性为0.995（95% CI，0.994 - 0.998；P < 0.001），观察者间一致性为0.994（95% CI，0.992 - 0.997；P < 0.001）。新方法与角膜散光呈正相关（P < 0.01）。与标准方法相比，该方法能够预测37%的角膜散光变异，而标准方法为21%。
图像分析方法在临床环境中对于客观量化实际翼状胬肉大小、形状及其对角膜前曲率的影响是有用、可靠且实用的。
