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What is Vision?

Vision or sight allows the sensing of light and the form, size, shape and color of objects in the field of vision. Average field of vision includes being able to see to either side of the body without having to move one’s head (peripheral vision). Normal human vision includes a level of ability to see in the dark using this same peripheral vision but there no “darkness receptors” in immediate forward vision.

What are Visual Impairments?

Vision impairments cover a very broad spectrum of conditions. Accident can cause loss or damage to vision but most vision loss is organic. It may be a condition present at birth or related to diseases of the eye (glaucoma, macular degeneration, retinosa pigmentosa) or may be side effects of other conditions such as diabetes. The prevalence of visual impairment increases with age.

Visual impairment means that a person's eyesight cannot be corrected to a "normal" level. Vision impairment may be caused by a loss of visual acuity, where the eye does not see objects clearly or may not see at all. It may also be caused by a loss of visual field, where the eye cannot see as wide an area as usual without moving the eyes or turning the head.

  • Visual impairments may affect reading, finding one’s way, judging distance and visual language.
  • Less than 10% of legally blind people are totally blind. A person is considered “legally” blind when the best corrected visual acuity is 20/200, or the person's visual field is 20 degrees or less.
  • Everyone has sensitivities to glare and a limited ability to see objects when direct light is behind them. Everyone has a limited ability to see in the dark. Many people wear eyeglasses and contact lenses to correct – or ‘mitigate’ – a limitation.
  • Some people experience “night vision impairment” or “night blindness.” The great majority of affected individuals are people having only limited vision problems … such as being unable to drive safely or comfortably at night. It is increasingly common as people age. Most can be helped with only a small number having more serious night vision problems.
  • Blurred vision, sometimes sufficient to reach the level of a vision impairment, is a common side effect of medication.

Who is Affected

Visual limitations can affect anyone. Whether they are the result of natural aging, an accident or a genetic predisposition, problems with vision can affect anyone regardless of age.

The American Foundation for the Blind reports the following statistics about vision impairments:

  • Although estimates vary, there are approximately 10 million blind and visually impaired people in the United States. 5.5 million are 65 or over.
  • Approximately 1.3 million Americans are legally blind.
  • Approximately 109,000 visually impaired people in the United States use white canes to assist in navigating the physical environment.
  • Just over 7,000 Americans use dog guides. Annually, approximately 1,500 individuals graduate from a dog-guide user program.
Diabetes is the leading cause of blindness in the US. The Centers for Disease Control (CDC) reported in 2005 that 21 million Americans have diabetes, 7% of the entire population.

It is normal for the structure of the eye to change as we age. The amount of light reaching the retina diminishes with age with noticeable changes by the time one reaches her mid-40’s. Normal aging also impacts the ability to see up close such as reading, seeing the computer screen, assembling small parts. The condition is called Presbyopia, easily corrected with glasses or contact lenses.

Our need for increased lighting for tasks increasing steadily with age. One needs approximately twice as much light at 40 as at 20 for tasks. A typical 80-year old needs three times the light of a typical 30-year old.

Looking at the Impacts

Our culture and our learning styles are based around a visual model and assumptions about a shared perception of how things look permeate the culture. A great deal of the information passed between people in conversation is not verbal but based upon visual cues that individuals read from each other during the interaction.

People who are blind will be able to direct you as to how they prefer information and if and how they would like your help. For many other people with a range of vision limitations, it will be less likely that the individual with the condition will provide clear guidance. Given the prevalence of vision limitations, it makes sense to anticipate that a portion of survivors will benefit from attention and some redesign of the physical and information environments. Making sure that people without good vision can find their way into and through your program is important. Ensuring that print or digital information can be accessed and used in a variety of ways will minimize visual limitations and likely be an asset for everyone.

Many assumptions and behaviors have to be modified when communicating with someone who has a severe visual limitation. It requires will have an affect on communications such as giving directions, teaching, providing informational materials and the emotional content of your conversation.