A good eyesight is the eyes’ ability to create a clear and precise image of reality on the retina. A blurred or distorted image is the result of eyesight disorders or ametropia (short-sightedness, long-sightedness or astigmatism). Glasses or contact lenses will correct your eyesight and allow you to have a good image on the retina.
The eye is a kind of miniature camera. The outside world, the objects around us give out light. The eyes send information on the light they perceive to the brain. The latter then transforms them into images. Here is how it works.