Peter Kaiser (York University, Toronto, Canada) has developed a webbook on vision, with lots of useful definitions and illustrations.

Vision research is replete with numbers describing visual structures (e.g., the number of fibers in the optic nerve). Here are many of those numbers, organized in a single list.

Within the animal kingdom one find huge variety in the design of eyes. Here's a website that provides a good sample of some of those eyes.

An interesting look at some light's basic properties, and their impact on images and vision.

The eye's optical components are responsible for focusing images on the retina. For a nice introduction to ocular optics take a look at these two websites, here or here. The first one says it's for kids, but don't be fooled.

For useful information on optical accomodation and refractive error.

It's a clouding of the lens, and this common problem affects more than half of all over 80 years of age in North America. It's a cataract, of course. Learn what it is.

Presybopia (the age-related increase in the near point of vision) and strategies for managing it.

Perhaps you've experienced them -- floaters - those little black specks that you may occasionally see. Here's an explanation of what they really are.

The facts about age-related macular degeneration, a leading cause of blindness.

A fact sheet on glaucoma.

United States Food and Drug Administration information on LASIK surgery, a procedure for reshaping the cornea to correct refractive error.