Vision Disabilities in Low Vision

描述(由申请人提供)：拟议的研究项目继续开发和验证心理测量仪器，旨在定量测量低视力患者的视力残疾。前一个项目期的进展包括用RASCH对自我评估问卷的分析进行验证，这些问卷要求受试者对执行具体活动的难度进行评级。这些研究表明：1)所有这些问卷都测量相同的视觉能力结构，2)视觉能力具有二维结构，阅读任务重载到一个维度，移动任务重载到另一个维度，3)视觉能力的一个维度是中心视觉(对数视力和对数对比敏感度的主成分)，第二维度很可能与视野的某些属性有关，4)并存疾病对视觉能力测量有轻微的混杂影响，5)设计用于评估功能视力的工具对不同诊断类别具有相同的校准，(6)低视力康复的效果表现为难度的项目特异性变化，而不是个人的视觉能力变化。目前提出的项目有四个具体目标：1)确定基于自我评估的功能视力测量与任务绩效测量之间的关系；2)确定视觉能力与周边和中央视野丧失的属性之间的关系；3)确定视觉能力和功能视觉测量对低视力康复的反应性；4)开发和验证测量低视力康复结果价值的方法。为了达到目标1，我们将进行阅读速度与字符大小、行走速度和障碍物回避、人脸识别、视觉搜索、追踪速度和准确性以及操纵任务的准确性的测量。为了达到目标2，我们将获得不同组患者的动态和静态周边视野测量和静态中心视野测量。为了达到目标3，我们将在低视力康复前后对我们活动清单中的目标和任务进行科目难度评级。为了实现目标4，我们将使用三分比较和支付意愿方法来衡量替代低视力康复结果的价值。

DESCRIPTION (provided by applicant): The proposed research project continues work on the development and validation of psychometric instruments designed to quantitatively measure vision disability in low vision patients. Progress in the previous project period includes validation with Rasch analysis of self-assessment questionnaires that ask subjects to rate the difficulty of performing specific activities. These studies demonstrated that: 1) all such questionnaires measure the same visual ability construct, 2) visual ability has a two-dimensional structure with reading tasks loading heavily onto one dimension and mobility tasks loading heavily onto the other dimension, 3) one dimension of visual ability is central vision (the principal component of log visual acuity and log contrast sensitivity) and the second dimension most likely is related to some attribute of visual fields, 4) co-morbidities have minor confounding effects on visual ability measurements, 5) instruments designed to assess functional vision have the same calibration for different diagnostic categories, and 6) the effects of low vision rehabilitation are manifested as item-specific changes in difficulty, rather than as person-specific changes in visual ability. The presently proposed project has four specific aims: 1) determine the relationship between functional vision measures based on self-assessments and task performance measures, 2) determine the relationship between visual ability and attributes of peripheral and central visual field loss, 3) determine the responsiveness of visual ability and functional vision measures to low vision rehabilitation, and 4) develop and validate methods of measuring the value of low vision rehabilitation outcomes. To achieve Aim 1, we will perform measures reading speed versus character size, walking speed and obstacle avoidance, face discrimination, visual search, tracing speed and accuracy, and accuracy of a manipulative task. To achieve Aim 2, we will obtain kinetic and static peripheral visual field measures and static central visual field measures on different groups of patients. To achieve Aim 3, we will obtain subject difficulty ratings to Goals and Tasks in our Activity Inventory before and after low vision rehabilitation. And, to achieve Aim 4, we will use triadic comparison and willingness-to-pay methods of measuring the values of alternative low vision rehabilitation outcomes.