the clear surface of the eye that light flows through, protective cover, filled with pain receptors, bends light waves so images can be focused on the retina
imperfection in the cornea, dimple, blemish
changes shape to bring objects into focus, focuses light on the retina
lens becomes cloudy
Hardening of the lens
presbyopia usually due to aging causes far sightedness
colored doughnut shaped muscle in front of the lens, controls the size of the pupil, restricting light coming into the eye
contains photoreceptors (rods, cones). 6 layers of different cells
Center of retina, greatest density of photo photoreceptors. contains mostly cones. lens tries to focus most of light onto this point
were the Optic nerves cross in the brain. so that information from from the right eyes goes to the left brain and a little to the right brain. versa vica
Visual Pathway in the Brain
Retina-Thalamus-Visual cortex (occipital lobe)what is seen on the left goes to the right side of the brain.
Its function includes relaying sensation, special sense and motor signals to the cerebral cortex, regulates sleep
occipital lobe/ processes visual images
Three different kinds of Cones
1. short wave length 2. med. wave length 3. long wavelength
Short wave length cone
blue cone detects
Medium wave length cone
green cone detects
Long wave length cone
red cone detects
caused by defective cones in the retina of the eye. sex linked inheritance. red-green blindness, blue-color blindness. either red, green or blue cones do not work.monochrome color blindess have no cones
accomplished by cones much faster than dark adapt. when going from a darkly lit place into a brightly lit one. The recovery of the eyes sensitivity to visual stimuli.
accomp.by rods when going from a brightly lit room to a dark room.takes about 30 min. difficulty with adapting can cause night blindness in older people.
rods and cones
sends visual information to the brain.
blind spot. no photoreceptors were the optic nerve attaches to the eye ball. hole in retina were the Axons from the eye leave to go to the optic nerve
eye shaped like a football. problem focusing on distance items
eye shaped like an egg. problem on focusing on close up items.
visual sensory receptors found at the back of the retina, color vision, and sharpness of vision. See in color and detail
visual sensory receptors found at the back of the retina, for non-color sensitivity to low levels of light. See in dim light
why we do not see the cells of our retina?
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