The eye is the first component of the sensory system of vision. Despite its small size, the eye is a very complex organ. The retina performs the first stage in visual perception. The optic nerve and the visual cortex of the brain are the next stages of visual perception.
Light enters the eye and passes through the cornea, the aqueous humor, lens and vitreous humor. It ultimately reaches the retina, the light-sensor of the eye.
Color vision is possible due to cones called cone pigments, which contain color responsive pigments. There are three kinds of color-sensitive pigments namely, Red-sensitive pigment, Green-sensitive pigment and Blue-sensitive pigment. Each cone has a pigment sensitive to the corresponding color.
Color blindness occurs when a cone does not function properly. This causes the inability to differentiate between colors. People suffering from color blindness may be able to see red or green, but confuse the two colors. This disorder affects men more than women. It is an inherited disorder.
Normal vision, known as vision or visual acuity, is the ability of a human being to read a Snellen eye chart from a distance of 20 feet. This is termed as 20/20 vision. A 20/40 vision is when a person stands 20 feet away from the chart, and can see what most people can see when standing 40 feet from the chart. In the United States, a vision of 20/200 is considered as legal blindness.
The general process of visual perception is universal and independent of any culture or race. It is also clear that individual differences such as impairment of sight and spatial skills also affect our visual perception.
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Vision Tests
10 August 2010 8:30 PM |
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In order to check the different functions and measure individual abilities to perceive details, vision tests can help individuals in reaching authentic and important decisions in treating their eyes. Vision tests evaluate and determine the gaps and defects of the visionary fields and checks the...
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Color Vision Tests
10 August 2010 8:30 PM |
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Color vision tests are performed to determine color blindness and the ability of the eyes in distinguishing the different colors. Although part of regular eye check up programs, color vision tests are also performed on patients who suffer from retinal diseases or are expected to...
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Peripheral Vision
10 August 2010 8:30 PM |
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Peripheral vision is obtained through the nerve cells located outside the center or the macula of the retina. These nerve cells enable the eyes to perceive objects and other movements outside the central visual field and the direct line of vision. While looking steadily towards...
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Vision Appraisal
10 August 2010 8:30 PM |
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Vision appraisal comprises of tests and examinations detecting defects in the functionalities of the visual system and evaluating the eyes’ ability to perceive things and their details efficiently. Vision appraisals may also include testing the ability of the eyes in perceiving and distinguishing colors. They...
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Age Related Macular Degeneration
10 August 2010 8:30 PM |
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Age-related Macular Degeneration or AMD is a common eye disease that causes progressive damage to the central part of the retina, also known as the Macula. AMD is the leading cause of visual impairment in the United States, and blindness in senior citizens of America,...
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Vision Care
10 August 2010 8:30 PM |
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Over one million Americans over the age of 40 face the threat of blindness or are currently blind. Another 2.4 million are visually impaired. These numbers are expected to double in the next 30 years. Diabetic retinopathy is one of the leading causes of blindness....
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Vision Therapy
10 August 2010 8:30 PM |
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Vision therapy refers to an individualized treatment program supervised by professionals in order to correct the cognitive visual deficiencies resulting from a number of causes and consequences. The program is also known as vision training of the entire visual system including eyes, brain, and body....
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Night Vision Security Cameras
10 August 2010 8:30 PM |
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As the name implies, night vision security cameras are used to capture images in darker environments. There are day/night vision cameras that allow you to see intruders trying to enter your home day or night time. These cameras ensure better security to your property. Most...
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Night Vision
10 August 2010 8:30 PM |
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Everyone knows that one cannot see anything in darkness. But imagine you are in a place that is cloaked in darkness and you are the only one who can see everything, even in the pitch dark. Technological advancements of the 21st century have made this...
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Dry Macular Degeneration
10 August 2010 8:30 PM |
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There are two types of Macular Degeneration or AMD. The first and more common type is the Dry Macular Degeneration. 85% to 90% of the cases of AMD or Age-related macular degeneration are of the dry or atrophic type. It is also a fact that...