What does Ms. Milton need to know about students with visual impairments?

Page 2: What It Means to Have a Visual Impairment

There is a great deal of jargon associated with visual impairments. Visual impairment, for example, refers to any level of vision loss that has an impact on the individual’s ability to complete daily tasks. Used loosely, the term often encompasses both blindness and low vision. Further complicating matters is the fact that individual students with visual impairments have quite different levels of visual functioning, and they use what vision they do have in different ways.

For example, Emily has low vision, which means that she needs to make accommodations such as using large print to read her assignments. On the other hand, Evan is legally blind and requires braille materials. To understand the distinctions between low vision and blindness, review the information in the boxes below.

Types of Visual Impairments

The sections below describe different types of visual impairments. The type of visual disability an individual has will affect his or her daily functioning and ability to use residual sight. It is important to be able to distinguish the different types of impairment, inasmuch as the distinction may affect the way a teacher structures classroom presentations and communicates information or materials.

Reduced Visual Acuity

Visual acuity refers to one’s clarity of vision. It is measured by a comparison with an established norm, the capacity of people to identify letters at a distance of 20 feet. If one’s visual acuity is 20/20, or is corrected to 20/20 with glasses or contact lenses, one is said to have “normal” vision. The larger the bottom number, the less clearly the individual sees. Thus, 20/200 visual acuity implies a significant loss of clarity. With this level of visual acuity, one would only be able to see the big “E” on the Snellen eye chart from 20 feet away, whereas someone with normal vision would be able to see it from 200 feet away.

Decreased visual acuity results in difficulty seeing detail. In a classroom, this might mean that students experience difficulties with:

• Reading standard-sized print in textbooks and handouts
• Reading signs, posters, bulletin boards, chalkboards, and overheads from their desks
• Seeing faces or identifying familiar people from a distance
• Performing tasks that require color discrimination

To illustrate, the following photos depict “normal” visual acuity and “impaired” visual acuity:

Normal acuity

Impaired acuity

Impaired Visual Fields

Having an impaired visual field is different from having decreased visual acuity, yet both may occur simultaneously. The visual field is the area one can see when looking straight ahead, typically 160 to 180 degrees wide. When a person’s visual field is reduced to 20 degrees or less, he or she is considered legally blind.

To illustrate, the following photos depict “normal” and “impaired” visual fields:

Normal visual field	Impaired peripheral fields
Impaired lower visual field	“Blind spots” in the visual field

Students who have impaired visual fields may experience problems with:

• Bumping into low objects or people next to them (peripheral field loss), causing potential challenges in crowded or busy areas such as the cafeteria or playground
• Missing drop-offs, such as curbs or steps (peripheral or lower field loss)
• Seeing straight ahead (central field loss)
• Tracking or following moving objects or people, possibly causing the person to bump into others when lining up for recess (peripheral field loss)
• Locating items in one’s vicinity, such as finding a dropped pencil or a specific reading passage (peripheral, central, or lower field loss)