The National Eye Institute (NEI)  describes low vision as difficulty with daily living even with the use of prescriptive lenses, medicines, or surgery.  For some, it is the challenge of dialing the phone when unable to read the phone book or when unable to see the numbers on the telephone. 

Common causes of Low Vision
Visual acuity of 20/70 or worse.  This means that the individual with a vision impairment must be 20 feet away while another with typical vision can see the same writing from 70 feet away.  The individual usually requires larger print when reading.

Glaucoma can cause the outer edges of vision to narrow.   

Diabetic Retinopathy causes a “swiss cheese” pattern of loss that makes accurate reading very difficult.  It can also cause light sensitivity.

A stroke or cerebrovascular accident (CVA) could cause loss of vision in the left visual fields, the right fields, upper fields, lower fields, or a combination.  It usually affects vision in both eyes.

For more information on each disorder and others not listed, click here:

Other qualities of Vision

In addition to visual acuity and visual field, other areas of vision influence the individual’s ability to function in the environment.

Contrast – Some individuals are unable to distinguish a white sock from the white bedspread behind it.  Or they cannot see a black car coming down the tarred surface of the road.  Functionally, they might do best with thick, black writing on a white background.

Glare management – For some people, two small headlights in the distance become magnified into a wide glow of light.  Bright light sources like the sun might cause a “wash out” effect; to them, it looks as if they see everything through a veil.  For others, a typical light bulb causes discomfort.

Light levels – Individual may need more light than is typical when reading.  In other cases, glare sensitivity makes more normal light levels intolerable.  The type of light bulb, the type of fixture, or the placement of the light source can impact the individual’s ability to use their vision optimally.

Muscle imbalance – When the two eyes are not moving in unison, individuals can see double images.  Sometimes, individuals tilt their head or close one eye in order to read.

Brain injury – The complex visual system develops in early childhood.  When brain injury happens due to trauma, stroke, or surgery, the result may be an inability to recognize objects, loss of some of the visual field, headaches, fatigue, or leaning to one side when walking.

What to do
Injury or disease to any of these areas can affect everyday function.  If you or a loved one are experiencing low vision without knowing the cause, it is important to seek the services of a qualified vision professional.  This could be a Low Vision Optometrist or your ophthalmologist.