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Article #6 by Dr Maha Orkubi
Statistics has shown that most people have a fear of being blind. We drive great pleasure from seeing the world around us. We judge people on their physical appearance, body language and their physical behavior. It seems that we shut off all other senses and depend largely on the sense of sight to experience beauty, pleasure, and happiness. Furthermore, we do not interact with individuals with visual impairments to get their views about beauty and their sense of well being. We even have bunch of myths around losing sight that confuse us and “keep us in the dark”. An example of such a myth: if a person with low vision use whatever sight he has. Therfore, to really understand about them we should learn about visual impairments and how does it impact on the individual.
Some terminology has to be clarified first. The definition of visual impairment depends on Visual Acuity, which is “the ability to distinguish forms or discriminate details at a specified distance”. Most people get it tested by reading numbers and symbols from a chart 20 feet away; thus the term 20/20 vision comes from. The eye should be able to see at this distance. If a person has a visual acuity 20/200 even after using corrective lenses, he is considered to have legal blindness. What this means is that Abbas can stand at a distance of 20 feet to see what other people can see from 200 feet. Thus Abbas has to come closer to things to see it better. Abbas will also have difficulty to use his vision in many situations, but it also means Abbas can succeed in regular school with special help. This term, “legal blindness” used medically and for educational purposes only.
Another term is used is Field of vision. A normal eye is able to see at range of 180 degrees. Individual with legal blindness can have restricted field of vision. 20 degrees or less. There are two kinds of field of vision: central and peripheral. To describe how a person with a good central field of vision and a restricted peripheral vision see, as if he sees the world through a narrow tube. While a person with good peripheral vision and a poor central vision see, they see blurry or a spotted central view and a clear field view. If Nahla’s field of vision is 10 degrees she will see a very limited area at one time, event though she might have good visual acuity.
Low vision means individuals with visual impairment who can read print with magnification lenses or large print books. Blindness means an individual can have light perception but their visual acuity is severely restricted. In the west it is estimated is (0.05) of school age children have visual disabilities.
Most common causes for visual disabilities are results of refraction errors. Myopia (near sightedness), Hyperopia (far sightedness), Astigmatism (blurry vision) are some illustration of refraction errors. In order for Zaid to be considered for educational services for visual disabilities his myopia must be significant enough to cause him his low vision.
Strabismus is a condition caused by weak muscles of the eye causes inability to focus on the same object with both eyes together. Nystagmis is a rapid involuntary eye movement. Nystagmis makes it difficult for an individual to focus or read smoothly.
Other causes for visual impairments are from Glaucoma, which means extra pressure in the eye that causes damage to the optical nerve. This damages causes damage in the peripherals vision. Cataract results in clouding of the lens, which causes (blurry vision) and low visions especially if they are correlated with Glaucoma. Diabetic Retinopathy a conditions results from the having retinal damage from diabetes. It causes people to have spots in their field of vision depending how severe it is.
Some visual Impairments are hereditary and effect children such as Congenital Glaucoma, Coloboma which is a degenerative desease and it causes damages to the visual field. Another hereditary decease is Retinitis Pigmentosa, which is degenerative and causes central vision to narrow. Retinopathy of Prematuraity, which results in a scar tissue that forms behind the lens of the eye. This disease occurs frequently to infants who are born premature and who needs very high oxygen level to survive.
For educational purposes there should a specific criteria for having children eligible for educational programs for visual disabilities. These educational services looks at how the visual impairment affects learning, makes special methods, and provide necessary materials and devices for their learning. It is also important to find the age of an individual acquired his visual impairment. A child who has blindness since birth has a quite different view of the world from a child whom has acquired it later in his life. For example, Suad who was born with sight impairment does not comprehend abstract concepts such as color, high, distance as Laila who had vision until she was eight years old. Laila does have a visual memory of these concepts. Even though, they both in programs for visual disabilities, their education’s needs differs. Laila require emotional support and different instructions for learning Braille while Suad’s require educational strategies to teach her those concepts. Next week column will describe the impact of visual impairments on the person.
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