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What is low vision? A re-evaluation of definitions
S J Leat1, G E Legge, M A Bullimore
1School of Optometry, University of Waterloo, Ontario, Canada.
Summary
This study re-evaluates definitions for visual impairment and disability. New criteria proposed for visual impairment include acuity <6/7.5 and visual field <146 degrees, while visual disability is defined by acuity <6/12.
Area of Science:
- Ophthalmology
- Public Health
- Disability Studies
Background:
- Current definitions of low vision, visual impairment, and disability are inconsistently applied.
- There is a need to distinguish between visual impairment and visual disability criteria.
Purpose of the Study:
- To re-evaluate and propose distinct definitions for low vision, visual impairment, and visual disability.
- To establish clear criteria for classifying visual impairment and disability.
Main Methods:
- Reviewed existing definitions of legal blindness and low vision.
- Proposed a distinction between criteria for visual impairment and visual disability.
- Considered visual acuity, visual field, and contrast sensitivity as potential criteria.
Main Results:
- Visual impairment defined by best visual acuity <6/7.5, visual field <146 degrees (Goldmann III-4e) or <109 degrees (III-3e), and contrast sensitivity <1.5 (PelliRobson).
- Visual disability defined by best visual acuity <6/12 or contrast sensitivity <1.05.
Conclusions:
- The proposed definitions differentiate between visual impairment and visual disability.
- These definitions aim to provide a clearer framework for classifying vision loss and its impact.