What is Low Vision?
Low Vision, also known as partial sight, is an impairment that cannot be resolved with conventional correction devices such as eyeglasses or contact lenses. In addition, neither surgery nor medication can correct the impairments that interfere with a person’s daily activities.
Common Conditions Causing Low Vision
Many diseases result in low vision or visual impairment; Glaucoma, macular degeneration, cataracts, retinitis pigmentosa and diabetic retinopathy are just a few. Normal vision is 20/20; when vision reaches 20/60, or worse, a person starts to experience difficulty with their daily activities. Simple tasks like reading or driving a car become a problem.
Low Vision: Common Types
- Generalized haze causes the feeling of a glare, coating, or film over the eye that may or may not extend over the entire field of vision.
- Blurred vision causes far and near objects to appear not focused, even when conventional spectacle correction is used.
- Peripheral vision loss, the inability for the eye to distinguish objects on one side of the eye or both, including anything directly below and/or above eye level. A person’s central vision is still present making objects directly ahead viewable. Typically, losing peripheral vision can affect mobility; if severe, reading speed can slow due to seeing minimal words at once (a.k.a. tunnel vision).
- Loss of central vision creates a blind spot or blurt, but peripheral (side) vision is still present. Ability to distinguish details in the distance, reading, and recognize faces are affected but mobility is usually unaffected.
- Extreme sensitivity to light is present when the eye is overwhelmed by the normal illumination levels. A glare can occur and or a washed out. A person may experience discomfort or even pain from normal illumination levels.
- Night blindness causes a person to be unable to see in dimly lit areas; restaurants, movie cinemas, or outside at night.
Functional Vision Problems
Difficulty Seeing:
- Computer Screens
- Gas Flam Height When Cooking
- Reading (telephone book, magazines, newspapers, etc.)
Problems:
- Threading a Needle
- Driving
- Seeing Traffic or Crossing Streets or seeing
Low Vision Examination: What’s included?
A Health and Medication History
- Overall health of patient and family.
- Patient and family conditions.
- Medications.
A Vision History
- Family history.
- Recent changes.
- Past treatments, medicines, surgeries, etc.
- Last examination date.
A Low Vision History
- A time-line from when vision problems began to the present.
An Eye Health Evaluation
- External and internal examination of the eye to determine eye health.
A Low Vision Refraction or Visual Acuity Testing
- A Bailey Lovie Acuity Chart and Feinbloom Distance Chart are used to help determine clarity and sharpness of both distance and near vision.
Visual Field Testing
- Determines how much peripheral vision is present.
Specialized Tests to Measure:
- Color vision
- Depth perception
- Contrast sensitivity
Low Vision Aids
- Non-prescription and prescription devices help enhance vision for people with low vision.
Examples:
- Special Low Vision Eye Glasses
- Magnifiers
- Microscopic Reading Glasses
- CCTV’s (Electronic Reading Machines)
- Check-Writing Guides
- Large Print Books
- Telescopic Lenses for Driving and Other Distance Tasks
- White Canes
To ensure the correct crutch is used it is best to seek advice from an Ophthalmologist or Optometrist.
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Photo Credits
Mike “Dakinewavamon” Kline
SlickFilms
