State the function of iris and yellow spot
in the human eye.
Answers
Teaching Students with Visual Impairments
Structure & Function
of the Eye
Learn more about the vision examinations, the differences between medical professionals, tests and tools used, and how to read an eye report including understanding visual diagnosis implications, visual fields and neurological visual impairments.
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By: Carmen Willings
teachingvisuallyimpaired.com
To better understand a student’s vision, it is important to know how each part of the eye contributes to a person's ability to see. Each area of the eye has an important role and must function properly in order for the eye to function properly. The following is a quick lesson in the structure and functions of the eye.
There are three ways areas, or underlying reasons for, a visual impairment. The first, there may be damage or a result of an injury to one or more parts of the eye essential to vision. This damage may interfere with the way the eye receives or processes visual information. Second, the eyeball may be proportioned incorrectly (have different dimensions than usual), making it harder to focus on objects or may not have developed correctly. And finally, the part of the brain that processes visual information may not work properly. The eye may be perfectly normal, but the brain is not able to analyze and interpret visual information so that the person can see.
Parts of the eye...
As part of the coursework for becoming certified as a Teacher of Students with Visual Impairments, it is necessary to take a class on the structure and function of the eye. Understanding the significance of each area of the eye can help a TVI understand the possible effects of various visual diagnosis.
1. Tear Layer
The Tear Layer (The Lacrimal System) is the first layer of the eye that light strikes. It is clear, moist, and salty. Its purpose is to keep the eye smooth and moist.
2. Cornea
The Cornea is the second structure that light strikes. It is the clear, transparent front part of the eye that covers the iris, pupil and anterior chamber and provides most of an eye’s optical power (if too flat = hyperopia/farsightedness; if too steep = myopia/nearsightedness). It needs to be smooth, round, clear, and tough. It is like a protective window. The function of the cornea is to let light rays enter the eye and converge the light rays.
3. Anterior Chamber
The Anterior Chamber is filled with Aqueous Humor. Aqueous Humour is a clear, watery fluid that fills the space between the back surface of the cornea and the front surface of the vitreous, bathing the lens (The anterior and posterior chambers. Both are located in the front part of the eye, in front of the lens). The eye receives oxygen through the aqueous. Its function is to nourish the cornea, iris, and lens by carrying nutrients, it removes waste products excreted from the lens, and maintain intraocular pressure and thus maintains the shape of the eye. This gives the eye its shape. It must be clear to function properly.
4. Iris
The iris is the pigmented tissue lying behind the cornea that gives color to the eye and controls the amount of light entering the eye by varying the size of the papillary opening. It functions like a camera. The color of the iris affects how much light gets in. The iris controls light constantly, adapts to lighting changes, and is responsible for near point reading (to see close, pupils must constrict)
