Vision Concept Map
Cornea
the transparent covering over the eye.
a barrier between the inner eye and the outside world,
involved in focusing light waves that enter the eye.
Pupil
the small opening in the eye through which light passes,
the size of the pupil can change as a function of light levels as well as emotional arousal.
The pupil’s size is controlled by muscles that are connected to the iris, which is the colored portion of the eye.
Lens
After passing through the pupil, light crosses the lens
a curved, transparent structure that serves to provide additional focus.
The lens is attached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects.
the lens will focus images perfectly on a small indentation in the back of the eye known as the fovea, which is part of the retina
Fovea - contains densely packed specialized photoreceptor cells
These photoreceptor cells, known as cones, are light-detecting cells.
Rods
located throughout the remainder of the retina.
specialized photoreceptors that work well in low light conditions
they lack the spatial resolution and color function of the cones
they are involved in our vision in dimly lit environments as well as in our perception of movement on the periphery of our visual field
Optic Nerve
Rods and cones are connected (via several interneurons) to retinal ganglion cells. Axons from the retinal ganglion cells converge and exit through the back of the eye to form the optic nerve
carries visual information from the retina to the brain.
Blind Spot
Even when light from a small object is focused on the blind spot, we do not see it. We are not consciously aware of our blind spots for two reasons:
First, each eye gets a slightly different view of the visual field; therefore, the blind spots do not overlap.
Second, our visual system fills in the blind spot so that although we cannot respond to visual information that occurs in that portion of the visual field, we are also not aware that information is missing.
Optic Chiasm
The optic nerve from each eye merges just below the brain at a point called the optic chiasm
At the point of the optic chiasm, information from the right visual field (which comes from both eyes) is sent to the left side of the brain, and information from the left visual field is sent to the right side of the brain.