Be sure to have your computer screen dimmed as much as possible. On a PC, you can do this with 'FN' and 'F6'. (To brighten it again, use 'FN' and 'F7'.)

Try setting your computer to high contrast black. If you have a PC, you can do this by right-clicking on your desktop, choosing 'personalize', and then clicking on 'windows color and appearance'.

I also recommend downloading and installing f.lux, and wearing sunglasses whenever watching TV or using the computer. f.lux filters the blue light out of your screen, making it easier on the eyes. You can download it for free here:

http://stereopsis.com/flux/

Finally, you can magnify the screen on a PC by holding down 'CTRL' and clicking the '+' sign. You can make it smaller again with 'CTRL' and '-'.