Optometrists and Occupational Health

Role of Optometrists in Occupational Health

The aim of occupational health can be summarised as “The adaptation of work to main and of each man to his job. “This implies that the physical and mental capacities of the individual has to be matched with the demands of the job. Vision is one of the most important attribute of man which has to be matched according to the job to improve work efficiency. Good eyesight can be directly linked to efficiency and safety, leading to increased productivity..

The role played by optometrist in occupational environment encompasses.

• Vision examination (screening and general) which includes pre employment tests and periodic recheck ups.
• Diagnosis of visual deficiency and correction where necessary and possible.
• Visual evaluation where visual requirements of the job are adequately matched with the visual abilities of the person at work.
• Possibly identify occupational causes of vision and eye problems.
• Advice on eye protection.
• To establish minimum visual requirements and standards for various jobs.
• The major factors affecting job performance include.
  • Qualifying visual factors.
  • Individual characteristics
  • Factors affecting visibility of task

Qualifying Visual Factors consist of

Visual Acuity: Maximum visual acuity is desirable for every job but not always essential. The relative value of demands on acuity must be weighed in each job. Dynamic visual acuity is more reliable measure of a persons ability to perform tasks as driving or inspection tasks on a conveyer belt near, intermediate and distant.

Accommodation: Though it cannot be compromized in some occupations like few sports, in most of the occupations it can be managed with the appropriate type of occupational prescription.

Ocular Motility: Some jobs require wide fixational movements machinist, textile mechanism, sports and this may need to be done without moving the head. This indicates need for large frames and lenses, and vision training to combine movements of head and eyes.

Depth Perception: The visual system can effectively judge distance of objects using monocular and binocular cues. At low levels of illumination depth perception is of very low order which may be a problem for some occupations like photographs who have to cut photographic papers and chemical solutions in dark room . For drivers and pilots is very essential.

Peripheral Vision: Drivers, pilots, and sports field is required large lenses should be used with frames and lenses being close to face and angled in conformance to facial features.

Colour Discrimination: Under photopic conditions the human visual system has a highly developed colour sense. In certain work like transport drivers, interior decorations, painting and pilots, colour discrimination is important.

Individual Characteristics: Perfect occupational prescription even with proper type of multifocal segment for job needs can be a failure of the segment does not fit the individual characteristics. These include the subjects age, height, head posture, eye posture, head turning and eye movements. For example, taller the individual higher is the centre of his lens with respect to a fixed work level.

Factors influencing visibility of a task included:

• size of task
• distance of task
• illumination
• contrast
• colour
• time available to view task
• movement of the task
• glare
• atmospheric conditions

The simplest of the factors is to adjust the level of illumination. Problems can arise due to insufficient as well as excess lighting at the work place. “Good lighting” is that which is adequate and sufficient for a given performance.

Contrast is differences in luminance between visual task area, background and environment and should not exceed certain maximum values. A relationship of 10:3:1 for normal task and 10:5:1 for precision tasks is recommended.

The concept of colour and colour contrast has been used in the industry to ascertain the moving parts and also to provide relief from fatigue.

Optometrists help in providing vision care services to a worker to make him visually efficient and visually alert. A perception for safety glasses should also fulfils employees visual requirements on the job. Vision care service in industrially advanced countries are being rendered in planned phases, its carried out in four steps.

Step 1: The Plant Environemtnal Survey: The optometrists determine:

• likelihood of injury and potential severity of injury from job operation.
• Optimum visual requirements for fast, safe and efficient operation of the machine.

Step II: Vision Screening Programme: Each worker is screened for visual acuity and binocular co-ordination besides stereopsis, colour vision, field of vision, etc. on job basis.

Step III: Remedial Programme: It makes the employee more productive by providing specialized job fitted pair of safety glasses.

Step IV: Fitting and Follow-up procedures: The protective cum corrective eye wear of an employee should be at least nearly in accordance with the frame and facial measurements of the wearer for comfort.

Vision care of industrial workers needs team work of occupational health specialists, industrial safety engineers, ophthalmologists and optometrists for successful implemenation of the programme.

The role of optometrists in occupational health can be illustrated with a few examples:

Transport Drivers: Driving both rail and road and pilots are the only occupation for which visual standards have been set by our government. The standards for road transport drivers are:

• Visual acuity – 20/20 in either or both eyes.
• unaided acuity of both eye should not be poorer than 20/70.
• Ability to maintain simultaneous binocular vision
• Have pupillary reflexes within normal limits
• Have a mass field of 1600 in horizontal meridian.
• Be able to distinguish true traffic light colours.

Prescription of occupational needs: The height of the vehicle above the ground level must be considered while determining the height of the bifocal segment.

Lathe Operator

Description of Occupation: The main work involves studying blue prints, adjusting the machine, setting control dials and during production the piece has to be checked with various gauges, etc.

Analysis of visual task: The work area is generally below the eye level.Common working distance to operate the machine is 18 to 20 inches, blue prints are held at an arms length and inspection of the piece is done at 12 to 14 inches.

QUALIFYING VISUAL FACTORS:

• Visual acuity : Near vision is required for machine work,etc.
• Ocular motility : Free and easy fixational movements are important.
• Depth Perception: Important while inspecting the machined piece.
• Peripheral vision :valuable for safe operation
• colour vision: No speical requirement.
• Other factors: Illumination should be proper.

Prescription of Occupational needs:

• Bifocals
• Trifocals
• Double segment bifocals
• Safety frames

Since we do not have standards for all jobs except the few mentioned earlier, Optometrists can help the industry to set standards of vision for various job. The qualifying visual factors i.e criteria fixation of standard are applied together with the characteristics of the particular working population, factors affecting visibility mainly the level of illuminance required for the job.

The optometric services are required in all occupations including aviation and sports. The optometrists make reasonably accurate assessment of the visual requirements of the job and the ability of the patient to carry out his work efficiently with comfort. In fulfilling, the patients overall visual needs the optometrists should be in a better position to give advice and to prescribe most effectively for the work situation.

REFERENCES:

1. Guide to occupational and other visual needs – Clark Homes
2. Eye and industry – Hedwig.S.Kuhn
3. Fine arts of prescribing glasses – Benjemin Midler,Melvin.L.Rubin
4. Ophthalmic optics – Sheady
5. Visual optics and refraction – Micheals .D.B
6. Directory and information on optometry – Optometric association of India
7. Industrial optometry – Dr. E. Vaithilingam

R. Hema & Dr. P P Santanam
IV year Student, Elite School of Optometry
Faculty, Elite School of Optometry

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