normal vision![click to hear](/images/speaker.jpg)
The image of an object is formed on the retina after passing through the lens, which, depending on the distance of the object, expands or contracts to give a sharp image.
retina ![click to hear](/images/speaker.jpg)
Inner membrane at the back of the eye covered in light-sensitive nerve cells (photoreceptors); these transform light into an electrical impulse that is carried to the optic nerve.
lens ![click to hear](/images/speaker.jpg)
Transparent elastic area of the eye; focuses images on the retina to obtain clear vision.
light ray ![click to hear](/images/speaker.jpg)
Line along which light emanating from an object propagates. The retina converts light rays into nerve impulses, which are then interpreted by the brain.
cornea ![click to hear](/images/speaker.jpg)
Transparent fibrous membrane extending the sclera and whose curved shape makes light rays converge toward the inside of the eye.
focus ![click to hear](/images/speaker.jpg)
Point where light rays converge to form an image; the brain interprets the retina’s upside-down image as right-side-up.
object ![click to hear](/images/speaker.jpg)
Light rays emanating from an object pass through the eye’s various media to form an inverted image on the retina.