I think my eyesight is okay. I know I’m a bit colourblind, but other than that and a lack of perspective, it’s okay.
These captchas, seen on the Oz-Astra web site forums though, these are too much. I know you have to fight spammers, but there comes a point where real humans are going to be defeated too, and eventually give up in frustration. Thankfully you can refresh the image and hope for something a bit more readable, but why not bring the difficulty level down from eleven so it’s not so hard?
(I’m not trying to single this site out; there are others that also frustrate. And I suspect this is down to an over-zealous implementation in vBulletin.)