Vision and Work - Fundamentals and Assessment Tools for Occupational Ergonomics - page 423

18
Vision and Work

18.1 Visual Acuity and Refractive Error ............. 18-2
Visual Acuity † Refractive Errors
18.2 Visual Acuity, Refractive Error, and Job
Performance ............................. 18-4
Visual Acuity † Refractive Error † Short-Working
Distances

James Sheedy
The Ohio State University

Vision is an integral part of nearly every job. Since vision is integral to nearly every job, a corollary is that
each job has a minimum level of vision or visual skills that is required for its proper performance. 1
For some jobs the minimum level of vision is specified as a job requirement. Such vision requirements
are strictly applied in situations where job performance is specifically dependent upon particular visual
characteristics or skills and where the cost of nonperformance is high in terms of safety and or clearly

identifiable costs. A common example is driving, a job (or task) for which a minimum level of corrected
visual acuity is required. Some states also have visual field (peripheral vision) requirements for driver
licensure. Other critical occupations such as law enforcement officers, firefighters, pilots, and military
among others have minimum vision requirements to obtain and

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or retain employment. These vision
requirements can include corrected visual acuity, uncorrected visual acuity, limits on refractive error
magnitude, binocular vision, depth perception, color discrimination, visual fields, and limits on patho-
logical conditions. Another example is requiring normal color vision for a job such as quality control
inspection where good color discrimination is important. In many cases minimum visual requirements
have been challenged legally on the grounds that they are discriminative. If the visual requirements can be
shown to be bonafide as related to critical task performance then they are usually defensible.
Although relatively few jobs have formal vision standards, good vision is a prerequisite for optimal
performance and visual comfort for most jobs. Vision is often screened at the time of application or
hire as a means to determine if the applicants have the necessary visual skills to perform certain tasks
and

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or to identify those applicants who may be in need of better visual correction prior to hire.
Besides poor performance, inadequate visual skills and

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or improper visual correction can result in
eye-related symptoms such as eyestrain, headache, irritated eyes, blurred vision, and fatigue. These pro-
blems are common when performing tasks at near working distances because they place great demands
upon accommodation (eye focusing mechanism) and binocular alignment. Such symptoms have been
particularly common among computer workers where specific workplace ergonomic factors often
increase stress upon the visual system. The costs of sub-optimally corrected vision can be quite high
with respect to the costs of providing eye care (Daum et al., 2004).

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1 Although people without vision can also work, considerable adaptations to the job are usually required. This
chapter addresses the visual aspects of work for those who are able to attain relatively normal visual acuity either
with or without optical correction. Adaptation of the work environment to the blind or those with low vision is
not covered in this chapter.

18-1