Leat S J, Legge G E, Bullimore M A
School of Optometry, University of Waterloo, Ontario, Canada.
Optom Vis Sci. 1999 Apr;76(4):198-211. doi: 10.1097/00006324-199904000-00023.
To re-evaluate definitions of low vision, visual impairment, and disability.
We review current definitions of legal blindness and low vision and how these definitions are variably based on disability or impairment. We argue for a definite distinction being made between criteria for visual impairment and visual disability, low vision being defined as the presence of a visual impairment that results in a disability. Visual impairment is defined according to population norms and a statistical cut-off is used. Visual disability is defined by consideration of the level of visual measures which result in measurable or reportable disability. We consider the evidence that contrast sensitivity should be a criterion for visual disability in addition to visual acuity and visual field.
According to the current information, we define visual impairment as best monocular or binocular visual acuity <(worse than) 6/7.5, total horizontal visual field <146 degrees (Goldmann III-4e) or <109 degrees (III-3e), and contrast sensitivity <1.5 (PelliRobson); we define visual disability as best monocular or binocular visual acuity <6/12 or contrast sensitivity <1.05.
重新评估低视力、视力损害和残疾的定义。
我们回顾了法定盲和低视力的当前定义，以及这些定义如何基于残疾或损害而有所不同。我们主张在视力损害标准和视力残疾标准之间做出明确区分，将低视力定义为导致残疾的视力损害的存在。视力损害根据人群规范进行定义，并使用统计临界值。视力残疾通过考虑导致可测量或可报告残疾的视力测量水平来定义。我们考虑了除视力和视野外，对比敏感度应作为视力残疾标准的证据。
根据当前信息，我们将视力损害定义为最佳单眼或双眼视力<（低于）6/7.5，总水平视野<146度（戈德曼III-4e）或<109度（III-3e），以及对比敏感度<1.5（佩利-罗布森）；我们将视力残疾定义为最佳单眼或双眼视力<6/12或对比敏感度<1.05。
