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Visual Standards and Occupation

by | Jan 1, 2023 | Manuscripts | 0 comments

Lakshmi Priya R.S, B. Optom

Fellowship in Optometry, Aravind Eye Care System, Chennai, India

 

One machine can do the work of more or less than fifty ordinary workers, however, no machine can do the work of one extraordinary worker unless their visual and physical functions are good. Many occupations require employers and employees to have a particular level of visual standards based on their work nature for personal and public safety. Most of us will think that perfect vision is 6/6 (20/20). (1) This value is only the standard for visual clarity. It means you can have measurable refractive errors like myopia, hyperopia, and astigmatism. In some occupations, there is a certain range of refractive error correction that is acceptable. There are some other components to be considered to attain good visual functions including near vision, central and peripheral vision, colour vision and contrast sensitivity. In addition to that, the ocular health of an individual also determines the accuracy of task performance as well as the safety of the individual at work. For example, some occupations need only distance and near vision along with colour vision like traffic police, machine operators, industrial work, etc. Some consider the visual field is important in their job nature like pilots, drivers, web developers etc., while other occupations require only good contrast sensitivity and other occupations need good depth perception. These are based on their specific job nature.

When the visual ability of the individual does not match the visual standards, it will affect the daily task performance of an individual at their workplace.

What are the tests to be performed?

  • Distance visual acuity (DVA) is performed at a distance of 20 feet (6m) using a Snellen chart. For distance, visual acuity should be 20/20 (6/6) either in UCVA or BCVA.
  • Near visual acuity (NVA) is performed by jaeger’s chart or by reduced Snellen at the distance of 30-35cm should be N6 (6/6) or N8 (6/9) and the contrast sensitivity should (CS) be lesser than 1.4 log units. These ranges vary for occupations.
  • Visual field (VF) test is performed to find any ocular conditions that affect the visual field either centrally or peripherally. It is performed either by tangent screen or by confrontation test. The degree of the visual field varies for occupations.
  • Colour vision (CV) is most important in many occupations to differentiate between two or more colours. It is performed by Ishihara (32 plates) stimulated for three types of dichromats, D15 test.

Table 1: Occupation and its Visual standards.

Occupations & visual Skills required Preferred visual test Visual standards
Air pilots and Air Traffic controllers (2)

  • Visual clarity is important to see distance as well as near targets.
  • Strong hand-eye coordination to activate the pilot.
  • Visual displays are important to track and monitor the movements of pilots.
  • Distance Vision
  • Near Vision
  • VF
  • colour Vision
  • Depth Perception
  • Contrast sensitivity
  • DVA:UCVA and BCVA not worse than 6/6(20/20) at 6m (20 feet).
  • NVA:N5/N6@35cm.
  • VF-190 degrees horizontally and 120 degrees vertically.
  • CV: 12/14(not including demonstration plate).
  • CS: 1.4 log units.
  • Stereopsis -80 arcsec.
Police (2)

  • Quickly changing fixation from a distance and near objects is an important skill.
  • For the shooting test, clarity of visual degree is important for police officers.
  • Distance Vision
  • Near Vision
  • VF
  • CV
  • BSV
  • DVA: UCVA should not be worse than 6/24, BCVA can be either 6/6 or till 6/12.
  • NVA: N5-N6@35cm to 40cm.
  • Field of view should be at least 120 degrees horizontally and 100 degrees vertically.
  • Cv 16/16 plated (without demonstrating plates) and monochromats are not acceptable.
  • Binocular single vision should be present.
Navy (2,4)

  • Movements of eyeballs should be full and free in all directions.
  • Must have binocular single vision.
  • Clarity or sharpness of vision for distance is important.
  • Distance Vision
  • Near Vision
  • Depth Perception
  • CV
  • DVA: UCVA should not be less than 6/9 or 6/6,BCVA should be 6/6.
  • Refractive correction should not exceed -1.50D in myopia and +1.50 Hypermetropic refractive error corrections.
  • NVA: should be N6 or N5@35-40cm.
  • BSV grade III is important (stereopsis)
  • Colour perception of grade1 is eligible.
Astronaut (2)

  • The sharpness of vision is important to gather information while in space flight, including on the space station.
  • Distance Vision
  • NVA
  • Depth Perception
  • DVA: UCVA should be 6/6 or BCVA 6/6.
  • NVA: N6 @35cm
  • Stereopsis should be at normal range.
Army and Military (2,5)

  • Visual clarity
  • Strong hand-eye coordination.
  • Ability to distinguish basic colours is important.
  • Distance Vision
  • Near Vision
  • VF
  • Depth Perception
  • Colour vision
  • Binocular single vision
  • DVA: UCVA should not be worse than 6/12,BCVA 6/6(20/20)@6m.
  • Refractive error should not exceed -3.50D for myopia and +2.50D for hyperopia.
  • NVA: n5 or n6@35cm
  • VF-190 degrees horizontally and 120 degrees vertically.
  • CV: 12/14(not including demonstration plate. CP grade 1 is eligible.
  • CS: 1.4 log units.
  • Stereopsis should not exceed more than -80 arcsec.
Railway staff (2)

  • Visual clarity
  • Strong hand-eye coordination for control of train movements and to ensure safety.
  • Ability to distinguish basic colours is important.
  • Distance vision
  • Near Vision
  • VF
  • Colour vision
  • BSV
  • Night vision
 In railways the vision criteria differ for certain positions or posts.

  • DVA: UCVA should not be worse than 6/12or 6/18, BCVA not worse than 6/9.
  • NVA: N6@40cm.
  • Normal field of vision range that is approx. 120 degrees is a binocular field of vision
  • CV 12/14 in Ishihara plates, D15 test also preferred to test for colour vision.
Drivers (2)

  • Driving is inarguably a highly visual task
  • Strong hand-eye coordination.
  • There are various aspects of visual function in driving like peripheral, central, vertical, and focused vision.
  • Most of the information they gather with their eyes.
  • Distance vision
  • Near Vision
  • VF
  • Depth Perception
  • Colour vision
  • Night vision
  • DVA: BCVA 6/6 UCVA should not be less than 6/12.
  • NVA: N8-N6@35cm.
  • VF: 110-150 degrees horizontally and vertically 20-40 degrees.
  • Binocular single vision should be present.
  • CV: 12/16 plates.
Firefighters (2)

  • strong eye-hand coordination is important for handling tools and fire vehicles, running drills etc.
  • visual clarity
  • Distance vision
  • Near Vision
  • VF
  • Depth Perception
  • Colour vision
  • DVA: BCVA worse than 6/12 are not eligible.
  • NVA: should not be worse than N18.
  • VF: horizontal less than 110 degrees are not eligible.
  • Monocular vision can affect peripheral vision, stereopsis, and colour use imaging devices.
  • The normal ranges of stereopsis and colour vision are eligible.
Surgeons and paramedics (2)

  • Strong hand-eye coordination, visual clarity (near as well as far), and contrast sensitivity are all important to handle dangerous scenarios, sense of accidents and emergency situations.
  • Distance Vision
  • Near Vision
  • VF
  • Depth Perception
  • Colour vision
  • Contrast sensitivity
  • DVA: UCVA and BCVA 6/9 or 6/6.
  • NVA: N6 or N5 @30-40 cm
  • VF: 90 degrees temporally to central fixation, 50 degrees superiorly and nasally, 60 degrees inferiorly.
  • CS is not worse than 1.4 log units.
  • There should be a normal range of colour vision and stereopsis are eligible.
Photographer

  • Visual clarity is important to see their targets clearly so that they can capture the image.
  • Distance Vision
  • Near Vision
  • VF
  • Depth Perception
  • DVA: UCVA should not be worse than 6/12, BCVA 6/6.
  • NVA: N6or N5 @35-40cm.
  • The central field of vision is important.
  • Stereopsis at least 25-40 arcsec.
  • CS: not worse than 1.4 log units.
Lifeguards (7)

  • Visual clarity (both distance and near vision), so that they quickly respond to the exposure and save lives in the surf.
  • Distance Vision
  • Near Vision
  • VF
  • DVA: UCVA worse than 6/18 are not eligible, BCVA 6/9 0r 6/6.
  • NVA: should not be worse than N12.
  • VF: Normal Binocular field of vision range approx. 120 degrees are eligible.
Construction workers (6)

  • Many visual functions require depth perception, contrast sensitivity, colour perception to operate machinery parts, handle dangerous chemicals etc.
  • Strong eye-hand coordination.
  • Distance Vision
  • Near Vision
  • VF
  • Depth Perception
  • Colour vision
  • DVA: BCVA not worse than 6/12.
  • NVA: not worse than N8 or N6.
  • Normal field of vision range that is approx. 120 degrees is a binocular field of vision.
  • CV 12/14 in Ishihara plates, D15 test also preferred to test for colour vision.
Web developers (2)

  • They spend more on visual displays to develop new websites, to reach the audience.
  • Distance Vision
  • Near Vision
  • Visual field
  • Contrast sensitivity
  • DVA: UCVA and BCVA 6/9 or 6/6
  • NVA: N6 or N5 @30-40 cm.
  • VF: 90 degrees temporally to central fixation,50 degrees superiorly and nasally,60 degrees inferiorly.
  • CS is not worse than 1.4 log units
Hairdressers (8)

  • Strong hand-eye coordination for their routine work like styling, colouring hair, and shaving and trimming facial hair.
  • Good visual clarity (near as well as distance )
  • Distance Vision
  • Near Vision
  • Visual Field(central VF)
  • Depth Perception
  • DVA: should not be less than 6/18.
  • NVA: N15 to N18 @50 – 60 cm.
  • Stereopsis 30-50 Arc sec

Conclusion:

Individual occupations elicit unique visual demands upon their workers and thus require different visual skills. The importance of visual standards is explained to Workers for the betterment of their performance in visual tasks by understanding The visual demands exerted by the occupation. The visual standards are the minimum expected level of vision that is required for the efficient and safe performance of tasks at the workplace. Thus, optometrists or eye care practitioners help in providing vision care services to a worker to make them visually efficient and visually alert. A perception for safety glasses should also fulfill an employee’s visual requirement on the job.

 

References: ‌

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