Most people use CRT (Cathode Ray Tubes) screens like TV screens. These screens have a single electron ray that has to light up dot after dot, line after line. It does this at a certain speed. With TV it is 50 Hz (50 screen scans per second) and with PC's it's 50 to 60 Hz by default. This 'refreshing' of the screen is why TV and computer screens flicker. This flicker can cause tremendous eye strain and headaches in some people.

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If you have a laptop or 'flat' screen, then you don't have this problem, because they don't flicker at all. Now if you read carefully you would have noticed I mentioned "by default" - more often than not the Refresh Rate on a PC screen can be adjusted to a higher frequency - of 85 Hz or more.

This reduces the flicker and the irritation and associated symptoms considerably. The sad thing is, when technical people set up PCs, they very seldom set the refresh rate to it's maximum ("optimal") rate and the user then works with the 50-60Hz refresh rate for ever after.

How to adjust the refresh rate on your PC

• Both the display adapter driver and monitor driver for your PC must be installed. If they are not installed, you may not be able to change your refresh rate. Contact the person who set up your PC or find and install it yourself.
• Right-click the desktop, click "Properties", then the "Settings" tab and then on "Advanced". Under the "Adapter" and "Monitor" tabs you'll find what drivers are installed. If it says "Default", then your driver is not installed.
• If your drivers are installed, you'll also find the drop-down where you can see and select a new refresh rate. When you change it, Windows asks you if you want to keep the new rate.
• If you don't say "yes", it reverts back to the previous refresh rate after about 15 seconds. This happens in case the refresh rate cannot be handled by the screen.
• The easiest of course is to just call your technical support person and have your drivers installed and refresh rate set optimally.

Useful resources:

South African Optometric Association
Tel: 011 805 4517

South African National Council for the Blind
Tel: 012 452 3811

Retina South Africa
Tel: 011 622 4904

Ophthalmological Society of South Africa

 

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