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3. CLASSIFICATION OF VISUAL IMPAIRMENTS There are several classifications of visual impairments according to different criteria. Important criterion for educational purposes is the consequence of visual impairment in the area of learning. Therefore, we often use classifications based on the visual potential of a pupil, especially the level of visus - visual acuity and visual field. According to the above mentioned, categories of visual impairments reflect more than just visual acuity. Students' ability to use vision, as well as how much they use other senses for learning, are aspects of each category. The terms low vision, functionally blindness, and blindness are often used to describe and categorize levels of vision. Each category is considered in terms of the degree of visual acuity and its implications for students' learning. • Low Vision. Generally, students with low vision are able to learn using their visual sense; however, they may need to have print magnified, contrast enhanced, or type font or size changed. Students in this category characteristically work more slowly and experience difficulty working with details. • Functional Blindness. People with functional blindness typically use a combination of modalities to function within their surroundings. Students in this category generally read and write using Braille alpjhabet. Some functionally blind individuals have sufficient vision to allow them to move around the classroom safely. Others, however, may require considerable accommodations to do so. Special attention should be paid to the spatial orientation and independent movement. These pupils should be also able to use special aids including computers. • Blindness. Near blindness and total blindness are included in this category. Near blindness occurs when visual acuity is reduced so greatly that learning takes place using data from other senses most of the time. Students with total blindness receive no stimuli from their visual channel. They depend entirely on input from other senses. • Impairment of binocular vision. This impairment is based on the restriction of visual function of one eye. These impairments belong to a group of functional disorders. The most characteristic consequence of impaired binocular vision is impaired spatial discrimination and understanding of space, especially depth recognition. Most students with this type of impairment are educated in mainstream schools. They require special support particularly in art classes, geometry and physical education.
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