Ординатура / Офтальмология / Английские материалы / Diagnosing and Treating Computer-Related Visual Problems_Sheedy, Shaw-McMinn_2003

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problem. This initial meeting is your case history. There is a wide range of possible situations. Some examples follow:

•The company wants you to evaluate an employee who has filed a worker’s compensation claim.

•A few selected employees are having problems.

•A new lighting installation is causing worker problems.

•The company wants advice on designing a new workplace.

•The company has just moved to new offices and wants to offer ergonomic and visual advice to those employees requesting it.

•The company wants to identify those computer workers who require special computer glasses.

•The company wants to implement pre-employment screening, etc.

At the initial meeting, you should endeavor to clearly understand their problem. You should also clearly tell the management what you believe you can accomplish and what you cannot. For example, you may be able to identify whether current lighting is good or bad and you can recommend how it can be made better, but you cannot specify the exact lighting system that they need. You should also ask about employee relations. Whenever you enter the workplace, you become an intermediary between employer and employee. You are likely to have been retained by the employer, so you should understand the employer’s attitude toward the situation and the employees in general. Determine whether there are any legal or union issues involved. Ask whether you are free to talk with employees and whether there are any topics to avoid. In some situations, you will need to be escorted everywhere within the company; in other situations, the areas of concern will be shown to you and you will be free to navigate on your own. It is usually important to determine whether the company provides eye care benefits; if so, you should ask for plan details. Determine whether other experts have provided related consultation and ask to review a copy of their report.

Take reasonable notes at the initial meeting; this is the beginning of the consultant report that you will write. Exchange business cards with everyone at the meeting. It is useful to know the people and their titles. Depending on the situation, you may begin your evaluation immediately after the introductory meeting or schedule it for a later time.

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It may be appropriate to survey employees to determine who is having problems. The questionnaire in Chapter 2, Figure 2-4, can be appropriate for this purpose. A tally of the results can indicate the extent of the problems and also indicate which employees require workplace visitation.

Before evaluating individual employees, determine the employer’s policies and attitudes about paying for the following: eye examinations; computer glasses (i.e., glasses that are different from daily wear glasses); individual ergonomic items, such as antireflection (AR) filters, copy stands, wrist rests, and keyboard trays; and larger items, such as computer displays and chairs. You will want to use this information to guide your conversations with individual employees. You do not want to mention corrective items to employees that raise expectations beyond the employer’s willingness to provide.

Before beginning your evaluations, you should have your equipment ready. The equipment listed in Box 12-1 can be useful. A camera (a digital camera is recommended) can be useful for including photos in your report. However, it is important to obtain approval from the

Box 12-1

Useful equipment for on-site evaluations

•Notebook

•Light-measuring equipment (luminance and illumination)

•Lens flippers to demonstrate adds and for accommodative facility testing

•Cover paddle

•Near visual acuity chart and near reading card

•Tape measure

•PD ruler

•Protractor, preferably clear plastic to see through

•Camera

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employer and also from any individual employee before taking photographs. Some companies prohibit all photography on the premises.

General Office Evaluation

Before visiting individual employees, it is best to perform an overview of the office setting. This enables you to understand some of the primary factors and to have made observations and measurements before visiting individual employees. It is also likely that your report will be organized to include general office recommendations (e.g., lighting, window treatment, general statement about computer displays) as well as recommendations for individuals. Employees may be in individual walled offices, but it is more likely that most employees work in an open office with cubicles.

The following observations and measurements should be made in a larger office containing several computer-using employees. Appendix 12-1 is an example of a form for a general office evaluation. Employees can be very helpful in this process. Casually talk with them and ask necessary questions as you perform this analysis. Tell them you are making general measurements, but it is best not to become involved with the problems of individual employees at this stage.

•Note the light sources in the room. Tungsten, fluorescent, sunlight? If the room relies on sunlight, do people work at night? If so, you may need to revisit at night.

•Do the light sources (e.g., overhead fluorescent) create glare for a horizontal gaze angle in the room? Measure the luminance of the light source from an angle that is typical for a computer user in that office. Angles can be measured by sight with the protractor. Find the location of the light controls (switches) and determine what options and light combinations are available. If there are several options, try each, make luminance measurements, and form an initial opinion regarding the optimal settings.

•Is window light a problem? Measure the luminance of the window. Are window treatments available? Do employees use them? Are the window treatments (blinds, shades) effective? Measure the luminance when the window treatment is used. Pay attention to sun patterns;

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open windows may be problematic only at certain times of the day. It may be necessary to visit at a different time of the day to evaluate.

•Walk through the office and measure prevailing illumination levels at desk level. Is it consistent throughout the office?

•Do the employees use localized lighting (e.g., desk lamps or undershelf lights)? Does such lighting seem to be useful or harmful?

•Note the general posture of employees. Are the displays consistently too high, too low, too far away? This can be a good time to observe whether any employees engage in awkward head positioning, perhaps indicating inappropriate multifocal correction or a need for visual correction. Note the employees with such problems. Do the chairs seem to provide appropriate support? Are

they generally adjusted properly? Are keyboards located at the right height? Do employees use reference documents? If so, are they located for easy viewing? Do employees engage in too much repetitive movement?

•Note the type of computer display(s) used. Liquid

crystal display or cathode ray tube? Size? Measure the luminance range of the screen by adjusting screen brightness. Are screen reflections problematic? If so, can the source of the problem be corrected (e.g., open windows)? Do employees use AR screens? Are they effective? Measure screen luminance with an AR screen in place.

Indoor Air Quality

It is not uncommon to have poor air quality in a workplace (Backman and Haghighat, 1999). This is sometimes referred to as sick building syndrome. There is a significant relationship between poor indoor air quality and eye symptoms such as irritation, contact lens problems, and dry eye symptoms. Other common symptoms associated with poor air quality include headaches, respiratory symptoms, nasal congestion, dry or irritated throat, asthma, and drowsiness. Poor air quality should be considered in workplaces with high incidence of such symptoms.

Poor air quality can occur in any building, but is particularly common in newly occupied buildings, especially in which construction is still under way or in which new construction is occurring.

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New carpeting, furniture, or draperies can also be sources of airborne irritants such as fire-retardant materials. Central ventilation disseminates irritants throughout the building. This also occurs if laboratories are not properly ventilated, causing poor air quality throughout the building.

Evaluation of Individual Employees

Assume the role of clinician when evaluating individual employees at their workstations. Your role is to determine the symptoms, screen the vision, determine whether the workstation ergonomics are adequate, and make recommendations. You should previously have obtained guidance from the employer regarding the items that will be provided for the employee. Individual employee evaluation at the workstation is similar to a clinical examination. A form for individual employee evaluation is at the end of this chapter (Appendix 12-2).

Typical objectives of the individual workstation assessment are to

1.Determine employee symptoms.

2.Determine whether eye care is indicated and indicate reason for referral.

3.Analyze the workstation ergonomics.

4.Recommend or implement, or both, workstation adjustments and changes to improve employee comfort.

If possible, try to first observe the employee at work without his or her knowledge. This can give a more accurate picture of habitual posture and work habits than asking the employee to assume his or her normal position when you visit. Note the employee’s posture, especially head attitude and working distance, with special attention to awkward posture resulting from spectacle correction. Also note usage and placement of reference documents.

The employee should be seated as usual at his or her workstation. It is best for you to sit beside the employee. Evaluate each of the following areas as appropriate to the case:

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•Case history. This step is significantly aided if the employee has filled out the symptom questionnaire. Ask about vision, eye, musculoskeletal, and glare-related symptoms (see Chapter 3). Also, determine the habitual corrective mode at the computer (no glasses, regular glasses, special computer glasses, contact lenses) and eye care history.

•Vision evaluation. The content of this part of the evaluation should be based on the symptoms, age of the employee, and your observations and measurements. The following areas should be considered:

•Head and neck posture, screen height. This evaluation should be performed on all employees. Ask the employee to assume his or her normal position before the computer. If this is different than what you had previously observed, investigate the difference. Measure the distance from eyes to computer display. If it is unreasonable (usually between 50–70 cm or 20–28 in.), determine the reason, if any. If the employee wears multifocal lenses, determine whether the lenses are used appropriately or whether they are causing unacceptable posture. Measure the gaze angle (should be 10–20 degrees downward) to the computer display. This can be determined by measuring the vertical distance between the horizontal plane of the eyes and the center of the screen (should be 4– 9 in. lower than the eyes for a viewing distance of 24 in.). The gaze angle can also be measured by viewing the employee from the side and using the protractor. Position the 0-degree axis of the protractor horizontal with the room and use a straight edge, such as the PD ruler, to point from eye to screen and note its angle relative to horizontal. Record whether the computer display is too high or low, and indicate whether multifocal correction seems inappropriate.

•Visual acuity. Determine whether the person is adequately corrected for the computer display. Acuity can be measured with the near point card. Use lens flippers to test whether lenses improve display visibility; this can be particularly useful to test presbyopic needs.

•Presbyopia. If the person is wearing a presbyopic correction, test whether it is appropriate for his or her work. Can the employee see clearly with a comfortable posture? Measure the range of clear vision through appropriate sections of the lenses. Use lens flippers

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to test the effects of altering the add power. Lens flippers can be used to demonstrate benefits of an add to beginning presbyopes.

•Vision function. This area of evaluation is indicated in prepresbyopic individuals with asthenopic symptoms. Testing can include the following: cover test for near heterophoria, near point of convergence, amplitude of accommodation, accommodative facility test, or a combination of these.

•Dry eye. If patient symptoms and history indicate dry eye, make recommendations. These can include the following: lower the computer display if indicated, eliminate excessive airflow, improve humidity if indicated, teach the patient to blink when symptoms occur, use artificial tears, or obtain an eye examination.

•Lighting evaluation. For this evaluation, it is best to sit in the employee’s chair to view the computer display as the employee does. Observe the display brightness compared to the general surrounding brightness—should the display brightness be adjusted? Determine whether glare sources are present (i.e., windows, overhead lights, desk lamps,

or other lamps). Use your hand as a visor to test the subjective effect on yourself. Measure the luminance of glare sources from the normal location of the employee’s eyes and the angle by viewing from the side with the protractor. Determine luminance ratios of glare sources to the display and compare to Illuminating Engineering Society recommendations. Have the employee sit in the chair, and ask him or her to perform the visor test. If you judge the glare source as bothersome, is there a simple remedy (e.g., rotating the workstation, blocking the light, turning it off, and adjusting window blinds)? Consider recommending that the employee wear a visor or recommending changes to the lighting system or window treatment. Evaluate current local desktop lighting, or whether such is indicated.

•Reflections evaluation. Sit in the employee’s chair. Use a file folder as a baffle to test whether blocking the impinging light improves display visibility. Determine whether the source of the reflections can be altered (e.g., turning off a light or using window blinds). Consider recommending an AR filter or hood for the display. Determine whether desktop surfaces are too bright. If so, measure the luminance and consider recommending a different surface or surface treatment.

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•Computer display. You have already observed and measured the

screen brightness and reflectance characteristics. Now judge the image size and quality. If the size is quite small, use the 3× rule test (see Chapter 10) to determine whether it is too small. If so, determine whether you can increase the size by changing the pixel setting or the screen magnification setting. Evaluate the color and contrast polarity of text; change if indicated and possible. If you can observe screen flicker (sometimes it appears to shimmer), evaluate the screen refresh rate setting. If there are significant and insurmountable shortcomings, consider recommending a new display.

•Body posture. Begin from the “ground up,” as discussed in Chapter 11. Make and implement (where possible) recommendations for change as you evaluate. Adjust chair height for proper thigh support and angle at knee, and make sure the patient’s feet are flat on the floor. Consider the need for a footrest for shorter employees. Adjust chair tension and back support. Evaluate keyboard position and height. Evaluate use of or need for arm rests. Adjust monitor height for proper visual angle. Evaluate need for copyholder or other work rearrangement.

•Furniture or workstation equipment. After evaluating the body posture and optimally adjusting the workstation furniture and equipment, evaluate whether the current equipment is appropriate. Significant shortcomings in chairs, keyboard height adjustment, arm rests, copyholders, and other items should be noted. Recommendations for new equipment or ergonomic accessories should be noted.

The most important part of the evaluation is the recommendations. These have accumulated as you have performed the above analysis. As in Appendix 12-2, first list workplace changes or counseling that you have already made. Then list any additional actions that are indicated, such as new equipment, ergonomic accessories, lighting changes, and window treatments. Use discretion in balancing the extent of the employee problem, the severity of the workstation shortcoming, the probable cost of the fix, and the employer’s willingness to provide.

Determine whether the employee should be referred for eye examination. It is important to indicate the reason for the referral so that the examining doctor can have benefit of your evaluation; in this way,