Purpose

Measuring patient-reported visual disability in Fuchs’ endothelial corneal dystrophy (FECD) may be helpful in determining when to intervene and for understanding the outcomes of intervention. In this study, we aimed to validate a new patient-reported visual disability questionnaire, the Visual Function and Corneal Health Status (V-FUCHS) instrument, in FECD before and after endothelial keratoplasty (EK).

Design

Cross-sectional study with instrument readministration at 6 weeks.

Participants

Patients with a range of severity of FECD, including after EK, and patients with healthy corneas.

Methods

The V-FUCHS instrument was developed based on patient interviews, expert consultations, and pretesting. Psychometric methods of classic test theory were applied to estimate reliability and validity, including testing V-FUCHS against Catquest-9SF, a cataract-specific visual disability questionnaire. Ordered polytomous Rasch-based partial credit models and item response theory diagnostics were used to define the response patterns.

Main Outcome Measures

Reliability (primary) and validity (secondary).

Results

The final instrument was completed by 65% of patients with a range of severity of FECD (n = 41), after undergoing EK for FECD (n = 70), and with healthy corneas (n = 28). Participants were phakic or pseudophakic. Exploratory factor analysis among FECD and patients who underwent EK showed 2 independent factors of visual disability: 7 items related to visual acuity and 8 items related to glare or diurnal variation. Retest reliability was substantial (intraclass correlation coefficient, ≥0.8, both factors). Among all patients, the visual acuity factor was correlated with Catquest-9SF scores (r = 0.65; P < 0.001; n = 96). The glare or diurnal variation factor increased with FECD severity (P < 0.001, n = 69) and was higher in FECD than healthy participants (P < 0.001). Diagnostics revealed that both factors were well calibrated and met Rasch model expectations.

Conclusions

The V-FUCHS instrument is valid and reliable for assessing visual disability in FECD. The instrument allows for standardized, comprehensive, and rapid assessment of disease-specific visual disability and may be useful in clinical practice and research as a patient-reported outcome measure.

中文翻译：

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视觉功能和角膜健康状况仪测量的Fuchs内皮角膜营养不良患者报告的视力障碍

目的

在Fuchs的内皮角膜营养不良（FECD）中测量患者报告的视力障碍可能有助于确定何时进行干预以及了解干预的结果。在这项研究中，我们的目的是在内皮角膜移植术（EK）之前和之后，在FECD中验证患者报告的新的视觉残疾问卷，即视觉功能和角膜健康状况（V-FUCHS）仪器。

设计

横断面研究，在6周时重新使用器械。

参加者

FECD严重程度不同（包括EK后）的患者以及健康的角膜患者。

方法

V-FUCHS仪器是根据患者访谈，专家咨询和预测试而开发的。应用经典测试理论的心理计量学方法来评估信度和效度，包括针对Catquest-9SF（一种白内障特定的视力障碍问卷）测试V-FUCHS。基于有序多态Rasch的部分信用模型和项目响应理论诊断程序用于定义响应模式。

主要观察指标

可靠性（主要）和有效性（次要）。

结果

在接受FECD EK（n = 70）和健康角膜（n = 28）的EKD严重程度范围（n = 41）的患者中，有65％的患者完成了最终的器械。参与者有晶状体或假晶状体。对FECD和接受EK的患者进行的探索性因素分析显示，有2个独立的视力残疾因素：与视敏度有关的7个项目和与眩光或昼夜变化有关的8个项目。重新测试的可靠性很高（两个因素之间的类内相关系数≥0.8）。在所有患者中，视敏度因子与Catquest-9SF得分相关（r  = 0.65；P <0.001； n = 96）。眩光或昼夜变化因子随FECD严重程度的增加而增加（P <0.001，n = 69），而FECD中的这些因素高于健康参与者（P  <0.001）。诊断显示，这两个因素均已正确校准并符合Rasch模型的期望。

结论

V-FUCHS仪器对于评估FECD中的视力障碍是有效且可靠的。该仪器可以对疾病特定的视力障碍进行标准化，全面和快速的评估，作为患者报告的结局指标，在临床实践和研究中可能很有用。