The eyes are undoubtedly the most sensitive and delicate organs we possess, and perhaps the most amazing. They present us with the window through which we view the world, and are responsible for four fifths of all the information our brain receives – which is probably why we rely on our eyesight more than any other sense.

 he images we see are made up of light reflected from the objects we look at. This light enters the eye through the cornea. Because this part of the eye is curved, it bends the light, creating an upside-down image on the retina (this is eventually put the right way up by the brain).  The retina is a complex part of the eye, but only the very back of it is light-sensitive,and is packed with photosensitive cells called rods and cones. These allow us to see images in colour and detail, and to see at night.  The lens focuses the image. It can do this because it is adjustable - using muscles to change shape and help us focus on objects at different distances. The automatic focusing of the lens is a reflex response and is not controlled by the brain. The lens focuses the image. It can do this because it is adjustable - using muscles to change shape and help us focus on objects at different distances. The automatic focusing of the lens is a reflex response and is not controlled by the brain.  Once the image is clearly focused on the sensitive part of the retina, energy in the light that makes up that image creates an electrical signal. Nerve impulses can then carry information about that image to the brain through the optic nerve.

In a hypermetropic eye, the light is not bent sufficiently so that it focuses at a point behind the retina. Here a person sees well for distance but near vision is difficult and causes strain. Hence hypermetropic people are called long-sighted.retina

What Is Myopia? Myopia "shortsightedness“ is a refractive defect of the eye in which collimated light produces image focus in front of the retina when accommodation is relaxed.refractive defecteyecollimated lightfocusretinaaccommodation