Lab Exam Flashcards
NORMAL VISION
The lens of the eye causes light rays to converge in order to focus the rays onto the retina. When light passes through the transparent structures of the eye, it refracts (bends). An image is projected onto the retina every time light passes through the transparent structures of the eye. The image is flipped by the lens but the brain interprets the image as if it were right side up. The rods and cones of the retina turn the light rays into nerve impulses. The impulses are transmitted through the optic nerve and sensory neurons until they reach the visual area of the brain. The brain then analyzes the information received.
CONVERGENT LENSES: CONVEX
A convergent lens causes the light rays that travel through it to come together
(converge). When light rays travel through a biconvex lens, the rays always converge to a
precise point called the focal point of the lens.
HYPEROPIA (FAR-SIGHTED)
A person suffering from hyperopia (far-sighted) can see distant objects clearly but nearby objects are blurry. This defect is caused by a shorter eyeball or by a lens that is not curved enough. Therefore, the lens is unable to make light rays converge onto the retina and the image is focused behind the retina. The problem can be corrected with a biconvex lens which will bring the rays even closer together and focus them onto the retina.
