[zeynel1]

For elderly users increasing the font size is not much help. The problem is with focus. The lens hardens with age and nearby objects appear out of focus. So 12pt and 24pt type will both be out focus:

http://www.scientificamerican.com/article.cfm?id=why-does-ey...

"When the lens loses its pliability it also loses its ability to focus over a wide range of distances. A hardened lens becomes more fixed on distant objects and cannot focus as well on nearby objects or vice versa."

[ggchappell]

You are correct about the hardened lens. But consider: if you can't read things up close, then you read things at a distance, and small fonts are difficult to read at a distance.

So, yes, larger fonts will help.

By the way, I'm speaking from experience here. I'm 43, which I don't think is quite "elderly", but presbyopia has hit me pretty hard in the past year. My eyes are still better than 20/20, but I now need reading glasses for up-close work. Without my glasses, small fonts can be a problem.

[zeynel1]

Yes, you are right. I wish there was a chart showing how this effect works. Also the eye may get used to a design. I used to think that HN font was too small and line spacing too thight but now it looks normal to me.