A visual impairment is any visual condition that impacts an individual's ability to successfully complete the activities of everyday life. Students with visual impairments are infants, toddlers, children and youths who experience impairments of the visual system that impact their ability to learn.
There are three classification systems for individuals with visual impairment that are used by education professionals. To be declared legally blind, an individual must have visual acuity of 20/200 or less, or have a field of vision restricted to 20 degrees or less at the widest point. However, this federal classification system is used primarily to determine eligibility for adult agency services.
For educational purposes, a specially trained teacher must determine that the visual impairment impacts the child's ability to learn, and this professional determination, with the agreement of the IEP team ensures access to special education services. To implement appropriate classroom accommodations for students with visual impairment, these students are also classified according to their level of functional vision:
- Low vision- students use their vision as their primary sensory channel
- Functionally blind- students can use limited vision for functional tasks but need their tactile and auditory channels for learning
- Totally blind - students use tactile and auditory channels for learning and functional tasks
A third classification system exists and is based on the advent of the visual impairment itself:
- Congenital- occurs during fetal development, at birth or immediately following birth; visual impairment is present before visual memory has been established
- Adventitious - occurs after having normal vision either through a hereditary condition or trauma; visual memory may remain.
Students with congenital visual impairment typically have more difficulty mastering visually strengthened concepts such as spatial orientation and many environmental concepts.
It is difficult to obtain an exact prevalence of visual impairment due to the often hidden nature of visual impairment in special education. Many students with visual impairments also have additional coexisting impairments and are thus classified in an alternate disability category. The National Dissemination Center for Children with Disabilities reports that the rate of occurrence for visual impairments in individuals under the age of 18 is at the rate of 12.2 per 1,000. Legal or total blindness occurs at a rate of .06 per 1,000. Current special education demographics obtained from the American Foundation for the Blind 2009 report that there are:
- 93,600 students who are visually impaired or blind;
- 55,200 students who are legally blind;
- 5,500 braille readers
Visual impairment is essentially an umbrella term used to describe the loss of sight that can be a consequence of a number of different medical conditions. Some common causes of visual impairment are glaucoma, retinopathy of prematurity, cataracts, retinal detachment, macular degeneration, diabetic retinopathy, cortical visual impairment, infection and trauma. These are just a handful of dozens of conditions impacting sight, and each condition has its own unique characteristics and clinical features. In addition, the impact of the visual impairment on individual learning is also tied to the onset, the severity, and the type of visual loss, as well as to any coexisting disabilities that may be present in the child. For this reason, all classroom accommodations, modifications, and strategies must be designed with the individual needs of each student with a visual impairment in mind. There is no one-size-fits-all model.
In addition to decreased visual acuity and visual field, a number of other vision problems may also impact the visual functioning of the student with visual impairment. There may be issues with sensitivity to light or glare, blind spots in their visual fields, or problems with contrast or certain colors. Factors such as lighting, the environment, fatigue, and emotional status can also impact visual functioning in many of these students throughout the day. Students who have the same visual condition may use their sight quite differently. To ensure accessibility to classroom instruction, it is essential that you know how your student is using his/her vision. A specially trained teacher of students who have visual impairments, working with the IEP team members, can help determine the best adaptations and learning media to use with each student.