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.
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.
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 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.