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Transcript of Vision
First of all, the human eye actually only sees a small portion of the light spectrum. The light energy we view is only 2.48 electron volts, and about 500 nanometers.
The Eye Itself
is a organ. It has many parts that function together to allow you to see. The eyeball is physically connected to the thalamus (in the visual cortex of the brain) by way of the optic nerve. The major parts of of the eye are: the cornea, iris, lens, macula, optic nerve, pupil, retina, and the vitreous.
...the light energy
This energy is absorbed by the surrounding environment, except for the actual color of the object.This light energy is reflected by the object and then received by the eye.
light entering the eye
The pupil is the dark center in the middle of the iris, the pupil determines how much light is let into the eye. It changes sizes to accommodate for the amount of light that is available.
The retina is the nerve layer that lines the back of the eye. The retina senses light and creates impulses that are sent through the optic nerve to the brain.
The Process of Vision
Light energy enters the eye where it is transformed into electrical impulses sent to the brain.
The cornea is the clear window of the eye. The cornea transmits and focuses light into the eye.
The way we see our world
The iris is the colored part of the eye, it helps to regulate the amount of light that enters the eye.
The lens is the transparent structure in the eye that focuses light rays onto the retina.
The macula is a small area in the retina that contains special, sensitive cells, that allow us to see fine details clearly.
The optic nerve connects the eye to the brain, the nerve carries the impulses formed by the retina to the brain where they are interpreted as images.
The vitreous is the clear, jelly-like substance that fills the middle of the eye.
Presented by Lash, Martin and Brown
As shown in the video, the eye uses accommodation to have clear acuity. [tHE dICTIONARY dEFINITION of aCCOMMODATION is: "The automatic adjustment in the focal length of the lens of the eye to permit retinal focus of images of objects at varying distances."]
acuity- sharpness, clearness, and distinctness of perceived images.
Having CLEAR sight
the tendency for a color to look the same under widely different viewing conditions
Normal vision occurs when light is focused directly on the retina rather than in front or behind it. A person with normal vision can see objects clearly near and faraway.
Nearsightedness results in blurred vision when the visual image is focused in front of the retina, rather than directly on it. It occurs when the physical length of the eye is greater than the optical length. For this reason, nearsightedness often develops in the rapidly growing school-aged child or teenager, and progresses during the growth years, requiring frequent changes in glasses or contact lenses. A nearsighted person sees near objects clearly, while objects in the distance are blurred.
Farsightedness is the result of the visual image being focused behind the retina rather than directly on it. It may be caused by the eyeball being too small or the focusing power being too weak. Farsightedness is often present from birth, but children can often tolerate moderate amounts without difficulty and most outgrow the condition. A farsighted person sees faraway objects clearly, while objects that are near are blurred.
The differences in some peoples' vision