The retina is a thin membrane at the back of the eye that contains 120 million photosensitive cells called rods and cones. You can think about these like pixels in a digital camera. When light falls on one of these photosensitive cells it is detected and a signal is sent to the brain via the optic nerve. Processing all the information from our retina allows us to see.

Light must be focused clearly on the retina and this requires a healthy cornea and a clear lens. Most of our clear vision that we use for fine detected in a central region of the retina called the macular.