computers

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Computers and Vision Computer work involves concentration of a task usually 50 cm or less away. To see clearly at these distances requires an unconscious effort. Several different muscles are needed when the eyes adjust to focus on a near point. One muscle inside the eye changes the shape of the eye's lens so that the eye is focused sharply and clearly on the monitor. Other muscles turn the eyes inward, directing them to the same point on the screen and moving the eyes quickly from one place to another. COMMON COMPLAINTS OF VDU OPERATORS The most commonly heard complaints by computer operators are of headaches, blurred vision for either near or far viewing distances, itching or burning eyes, eye fatigue, flickering sensations, double vision, slow refocusing and frequently losing the place when moving eyes from printed material to the screen, and difficulty seeing distant objects clearly after prolonged computer use. These complaints are symptoms of what is commonly called eye strain. FURNITURE, POSTURE AND POSITION The use of appropriate furniture and proper positioning of hard copy can help prevent discomfort and reduce the frequency of work-related problems experienced by computer operators. -adjustable chairs allow the user to set the chair for most comfortable height and back support. -the top of the monitor should usually be 10 degrees (and the centre of the screen 20 degrees) below the user's straight-ahead seeing position. The appropriate distance from the viewer's eyes to the screen should be approximately 35 to 50 cm (14 to 20 inches). -reference material should be placed as close as possible to the VDU screen. This avoids large head and eye movements which are tiring. -where possible, reference material and the VDU should be placed the same distance away from the eyes. This reduces the need for frequent changes of focus, which can contribute to visual discomfort caused by unconscious effort. TIPS ON LIGHTING AND GLARE CONTROL FOR VDUs Lighting needs vary with individuals, with the nature of the task at hand and with the layout of the office, but it is usually desirable for the monitor brightness to be three to four times greater than ambient office lighting. Whenever possible a lower level of general room lighting should be maintained where computers are in use. -It is not possible to specify the light level which should be used due to the variety of activities which may be carried out in an office at any one time. -The characters on the computer monitors should be significantly (around 10 times) brighter than the screen background. -Reflected glare on monitors should be minimised by positioning screens so that windows and other sources of bright light are not behind the operator. Operators should not sit facing an unshaded window or other source of bright light. Curtains, blinds and other means of shading should be used to reduce glare. Small hoods can be attached above the screen to shield it from excessive overhead light. -Localised lighting sources such as flexible lamps may be used for other deskwork. These should be shielded to avoid glare on the work surface or monitor and to prevent sharp contrasts. -Avoid white or coloured clothing if it causes a reflection on the screen. TAKING REST BREAKS CAN REDUCE FATIGUE Rest breaks are important because computer work often requires intense concentration. If possible work with screen based equipment should be interspersed with other tasks. Rest breaks may need to be scheduled into a work routine if operators do not take sufficient time away from the screen of their own accord. Glancing away from the screen for a second or two every few minutes will make work with computers more comfortable. POOR VISION AND COMPUTER USE - A BAD COMBINATION Vision problems which are not usually noticed often become a source of complaint for computer operators. This is because computer work imposes greater visual demands than traditional office work. It is likely that previously unnoticed vision conditions are one of the most common reasons for vision related complaints by computer operators. The Optometrists Association Australia recommends that staff have their eyes thoroughly examined before they begin work with screen based equipment and then on a regular basis. The examining optometrist should be informed of any specific visual problems which the person has experienced. Wherever possible the distance and angle of the monitor at which the operator is working should be described. Proper optometric care can solve most vision problems. COMMON VISION PROBLEMS THAT MAY AFFECT COMPUTER WORK Longsighted people see distant objects more clearly than those close up, but usually have to make an additional effort in both situations. A mildly longsighted person who is generally able to perform normal seeing tasks such as driving or reading without prescription spectacles may require them to overcome blurred vision or visual discomfort when working at a VDU. Presbyopia is a vision condition that is part of the natural ageing process and usually is first noticed in the mid-forties. Presbyopia reduces a person's ability to focus clearly on close work. Reading glasses for use while operating a VDU may be required. If bifocals are necessary they must be designed specifically with VDU operation in mind. If suitable bifocal and trifocal reading segments are to be prescribed, information such as the measurement of the distance from the operator's eyes to the screen must be given to the optometrist. Astigmatism is another common vision disorder that blurs vision at all distances and which may cause discomfort to the VDU operator. It is a condition in which the front surface of the eye or cornea is not perfectly round, but is oval shaped. Prescription lenses that are worn only when using a VDU can help operators with mild astigmatism. People with a greater degree of astigmatism may need to wear glasses all the time. There are many other conditions which make the VDU screen appear blurred, increase susceptibility to glare, or otherwise make VDU use difficult. Among these are poor eye co-ordination, shortsightedness and eye focusing problems. Your optometrist can diagnose these conditions and advise you on treatment suitable for VDU operation and normal seeing tasks.

Computers and Vision

Computer work involves concentration of a task usually 50 cm or less away. To see clearly at these distances requires an unconscious effort. Several different muscles are needed when the eyes adjust to focus on a near point. One muscle inside the eye changes the shape of the eye's lens so that the eye is focused sharply and clearly on the monitor. Other muscles turn the eyes inward, directing them to the same point on the screen and moving the eyes quickly from one place to another.

COMMON COMPLAINTS OF VDU OPERATORS

The most commonly heard complaints by computer operators are of headaches, blurred vision for either near or far viewing distances, itching or burning eyes, eye fatigue, flickering sensations, double vision, slow refocusing and frequently losing the place when moving eyes from printed material to the screen, and difficulty seeing distant objects clearly after prolonged computer use. These complaints are symptoms of what is commonly called eye strain.

FURNITURE, POSTURE AND POSITION

The use of appropriate furniture and proper positioning of hard copy can help prevent discomfort and reduce the frequency of work-related problems experienced by computer operators.
-adjustable chairs allow the user to set the chair for most comfortable height and back support.
-the top of the monitor should usually be 10 degrees (and the centre of the screen 20 degrees) below the user's straight-ahead seeing position. The appropriate distance from the viewer's eyes to the screen should be approximately 35 to 50 cm (14 to 20 inches).
-reference material should be placed as close as possible to the VDU screen. This avoids large head and eye movements which are tiring.
-where possible, reference material and the VDU should be placed the same distance away from the eyes. This reduces the need for frequent changes of focus, which can contribute to visual discomfort caused by unconscious effort.

TIPS ON LIGHTING AND GLARE CONTROL FOR VDUs

Lighting needs vary with individuals, with the nature of the task at hand and with the layout of the office, but it is usually desirable for the monitor brightness to be three to four times greater than ambient office lighting. Whenever possible a lower level of general room lighting should be maintained where computers are in use.
-It is not possible to specify the light level which should be used due to the variety of activities which may be carried out in an office at any one time.
-The characters on the computer monitors should be significantly (around 10 times) brighter than the screen background.
-Reflected glare on monitors should be minimised by positioning screens so that windows and other sources of bright light are not behind the operator. Operators should not sit facing an unshaded window or other source of bright light. Curtains, blinds and other means of shading should be used to reduce glare. Small hoods can be attached above the screen to shield it from excessive overhead light.
-Localised lighting sources such as flexible lamps may be used for other deskwork. These should be shielded to avoid glare on the work surface or monitor and to prevent sharp contrasts.
-Avoid white or coloured clothing if it causes a reflection on the screen.

TAKING REST BREAKS CAN REDUCE FATIGUE

Rest breaks are important because computer work often requires intense concentration. If possible work with screen based equipment should be interspersed with other tasks. Rest breaks may need to be scheduled into a work routine if operators do not take sufficient time away from the screen of their own accord. Glancing away from the screen for a second or two every few minutes will make work with computers more comfortable.

POOR VISION AND COMPUTER USE - A BAD COMBINATION

Vision problems which are not usually noticed often become a source of complaint for computer operators. This is because computer work imposes greater visual demands than traditional office work. It is likely that previously unnoticed vision conditions are one of the most common reasons for vision related complaints by computer operators.

The Optometrists Association Australia recommends that staff have their eyes thoroughly examined before they begin work with screen based equipment and then on a regular basis.
The examining optometrist should be informed of any specific visual problems which the person has experienced.
Wherever possible the distance and angle of the monitor at which the operator is working should be described. Proper optometric care can solve most vision problems.

COMMON VISION PROBLEMS THAT MAY AFFECT COMPUTER WORK

Longsighted people see distant objects more clearly than those close up, but usually have to make an additional effort in both situations. A mildly longsighted person who is generally able to perform normal seeing tasks such as driving or reading without prescription spectacles may require them to overcome blurred vision or visual discomfort when working at a VDU. Presbyopia is a vision condition that is part of the natural ageing process and usually is first noticed in the mid-forties. Presbyopia reduces a person's ability to focus clearly on close work. Reading glasses for use while operating a VDU may be required. If bifocals are necessary they must be designed specifically with VDU operation in mind. If suitable bifocal and trifocal reading segments are to be prescribed, information such as the measurement of the distance from the operator's eyes to the screen must be given to the optometrist. Astigmatism is another common vision disorder that blurs vision at all distances and which may cause discomfort to the VDU operator. It is a condition in which the front surface of the eye or cornea is not perfectly round, but is oval shaped. Prescription lenses that are worn only when using a VDU can help operators with mild astigmatism. People with a greater degree of astigmatism may need to wear glasses all the time.

There are many other conditions which make the VDU screen appear blurred, increase susceptibility to glare, or otherwise make VDU use difficult. Among these are poor eye co-ordination, shortsightedness and eye focusing problems. Your optometrist can diagnose these conditions and advise you on treatment suitable for VDU operation and normal seeing tasks.