OK I don't know if this is the right forum for this discussion; but it's a starting place.

When I read for a while on the Internet, and it is often forums like this one which don't let you change the colour scheme, my eyes get sore and the text starts to move from side to side and I find it hard to concentrate. I have had my eyes tested and wear glasses as I am longsighted. But this is worrying me. Does anyone know what it could be? Could it just be my eyes struggling to focus?

Any help?