The eye is a round globe or sphere with a hole at the back where the eye nerve comes into the eye and an opening at the front that you see through.
At the front you get the cornea which is a transparent skin which is very sensitive to light and needs to stay moist to be comfortable. Just behind the cornea we have the iris or colour of the eye with an opening in the centre called the pupil. The pupil constricts with bright light and dilates when it is dark to allow the right amount of light into the eye.
Just behind the iris is the lens of the eye that helps you to focus from far to near. This function diminishes as we get older and therefore we need glasses to read. The lens of the eye is transparent but it yellows and gets milky as we get older.
The inside of the eye is filled with a jelly-like substance called the vitreous which again must be transparent to see clearly. The back of the eye is lined on the inside by the retina a layer with very specialized nerve endings that allows us to see. Right in the centre is the macula, a very small area on the retina that provides most of our central vision.
The retina is connected with the optic nerve to the brain. The function of the eye is to pick up an image of whatever you are looking at and relay that to the brain where vision takes place. It is much the same as a TV where the satellite dish picks up the signal and then relays it to the TV where the image appears. If there is something wrong with the dish or the cable the image on the TV is poor.
The purpose of glasses is to get the image that falls on the retina in focus. Too strong or too weak lenses will put the image out of focus. Then it is up to the eye to send a clear image to the brain.
Among the many common age related eye diseases, like Cataracts, Glaucoma, Diabetic Retinopathy and Dry Eyes, we would like to have a look at AMD or Age Related Macular Degeneration.