This is a wonderful resource on visual perception and sensation. It is a web book that gives details about how great our sense of sight really is. This site covers many different topics that deal with how we perceive things visually and how our brain interprets these sensations. It will certainly give anyone a deeper appreciation about how precious our eyes really are to us.
It is extrememly easy to use. There is no membership or login required, only a internet browser. It is well set up so that the web user can easily click on the link to the topic of interest without hesitation.