Massof R W
Lions Vision Research and Rehabilitation Center, Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Optom Vis Sci. 1998 May;75(5):349-73. doi: 10.1097/00006324-199805000-00025.
This study presents and tests a method of measuring vision disabilities. Based on the model presented in the first paper of this series, cognitive and motor activities ("tasks") are organized in a hierarchy that identifies the tasks' behavioral goals (purposes) and the social objectives the goals serve. Two latent variables important to the definition of vision disability are identified: "value of living independently" and "visual ability for independent living." The basic principles of the Rasch measurement model are reviewed, and Rasch models are used to measure the two variables that define vision disability. The need for rehabilitation to meet each goal is represented by "rehabilitative demand," a mathematical function of the measurements made of the value and difficulty of achieving each goal independently.
Over 400 patients with low vision rated both the importance and difficulty of independently achieving each of 24 goals. Rasch analysis was used to derive interval measures of the social value of each goal, the value that individual patients placed on each goal relative to the derived social definition of independence, the visual ability required to achieve each goal without help, and the visual ability of individual patients to live independently. A rehabilitative demand function was ascertained from the judgments of 17 AAO Diplomates in Low Vision through triadic comparisons and multidimensional scaling.
Self-care had the greatest "social value" for independence; performing music had the least. Recreational reading required the greatest "visual ability" to accomplish independently; self-care required the least. Rehabilitative demand was linear with value and nonmonotonic with difficulty.
Rehabilitative demand, an algorithm for defining vision disability, incorporates interval measures of visual ability and the value of independent living estimated from patient-based assessments, a social scale of the value of activities relative to independent living, and a consensus opinion of low vision experts on the prioritization of the need for rehabilitation.
本研究提出并测试了一种测量视力残疾的方法。基于本系列第一篇论文中提出的模型，认知和运动活动（“任务”）被组织成一个层次结构，该结构确定了任务的行为目标（目的）以及这些目标所服务的社会目标。确定了对视力残疾定义至关重要的两个潜在变量：“独立生活的价值”和“独立生活的视觉能力”。回顾了拉施测量模型的基本原理，并使用拉施模型来测量定义视力残疾的两个变量。实现每个目标所需的康复需求由“康复需求”表示，它是对独立实现每个目标的价值和难度进行测量的数学函数。
400多名低视力患者对独立实现24个目标中每个目标的重要性和难度进行了评分。使用拉施分析得出每个目标的社会价值的区间测量值、个体患者相对于推导得出的独立社会定义对每个目标赋予的价值、无需帮助实现每个目标所需的视觉能力以及个体患者独立生活的视觉能力。通过三元比较和多维标度从17名美国眼科学会低视力专科医师的判断中确定了康复需求函数。
自我护理对独立具有最大的“社会价值”；演奏音乐的社会价值最小。休闲阅读独立完成需要最大的“视觉能力”；自我护理所需的视觉能力最小。康复需求与价值呈线性关系，与难度呈非单调关系。
康复需求作为一种定义视力残疾的算法，纳入了视觉能力的区间测量值、根据基于患者的评估估计的独立生活价值、相对于独立生活的活动价值的社会量表，以及低视力专家对康复需求优先级的共识意见。
