Low vision involves not being able to see the world around you very well even with corrective devices like glasses or contact lenses. (Learn More)

There are different ranges of vision loss, often measured by refractive differences in visual acuity based on the Snellen chart. Loss of peripheral or central vision can lead to a diagnosis of low vision, as can spots of vision loss around the visual field. (Learn More)

There are several potential causes of low vision, from hereditary and congenital disorders to injury and infection. (Learn More)

As medical treatments and technology both improve, there are many devices that can be helpful for people with low vision. Low vision rehabilitation can help you use the vision you currently have to maximum potential. (Learn More)

What Does ‘Low Vision’ Mean in Medical Terms?

Low vision refers to a range of vision loss that cannot be fully corrected with surgery, corrective lenses, or medication.

Causes of low vision include infections, hereditary diseases, or chronic eye disorders.

In the United States, legal blindness occurs when visual acuity, or clarity of sight, in the dominant or better eye measures 20/200 or less. This means that someone with this vision, measured by the Snellen chart, can see at 20 feet what someone with perfect visual acuity can see at 200 feet.

There are other measures of low vision, including loss of peripheral vision and blind spots around the visual field. The American Community Survey from 2014 found that 2.3 percent of people ages 16 and older have a visual disability or low vision.

How Can You Tell if You Have Low Vision?

The range of vision changes or vision loss includes:

  • Mild vision loss. From 20/30 to 20/60 is a common range of poor eyesight for people who have myopia, presbyopia, hyperopia, and astigmatism. It is near-normal vision. When corrected vision measures in this range, it may be treated with a new eyeglass prescription.
  • Moderate visual impairment. Ranging from 20/70 to 20/160, this is moderate low vision and may require additional forms of corrective wear or surgery to improve visual acuity.
  • Severe visual impairment: Ranging from 20/200 or worse, this form of severe low vision is tough to treat and could lead to a diagnosis of legal blindness.
  • No light perception. This is total blindness, or not being able to distinguish any objects or colors due to the inability to process light.dark room

You may receive a diagnosis of low vision if:

  • You lose best-corrected visual acuity (BCVA) in the dominant or clearer of your eyes to 20/70 or worse.
  • You lose vision in your periphery or develop blind spots across your visual field.
  • You meet the requirements for being legally blind.

It is important to know that visual acuity is the most common measurement of vision, but it is not the only form of vision change. Refractive errors, including nearsightedness and farsightedness, are the most common progressive eye disorders. Some conditions may allow someone to have 20/20 vision while also suffering vision loss that could lead to a diagnosis of low vision.

Other symptoms of low vision include:

  • Trouble reading.
  • Difficulty using computers or tablets.
  • Discomfort watching TV.
  • Trouble recognizing faces.
  • Difficulty understanding switches or dials.
  • Trouble with daily activities like driving or shopping.
  • Trouble understanding how far away an object is (depth perception).

Potential Causes of Low Vision

eye with cataracts

While extreme refractive errors may be one of the most common causes, other causes of low vision include:

  • Cataracts, which can cause hazy or blurry vision.
  • Macular degeneration, which can partially obscure central vision.
  • Diabetic retinopathy, which can cause blurriness, blind spots, and visual distortions.
  • Glaucoma, which often involves progressive loss of peripheral vision.
  • Retinitis pigmentosa, which also reduces peripheral vision, along with reducing low-light vision.
  • Light sensitivity and loss of color or light contrast, which are symptoms of other conditions that can also make it hard to see.
  • Eye injuries that may damage the cornea or retina.
  • Hereditary conditions.

When children are born with low vision, this is typically a hereditary or congenital condition. While these can be managed, they are rarely curable.

Vision loss in older adults is common due to age-related eye conditions, like glaucoma, macular degeneration, and cataracts. These conditions have varying levels of treatment, from monitoring the disease’s progress and prescribing different glasses to prescription medications and eye drops to surgery.

Adults of working age, between 20 and 64 years old, may suffer vision loss due to injury or illness, including some genetic conditions. In some instances, the disease’s progress can be slowed, but vision loss means that an adult will have to learn to navigate the world in new ways, which may be traumatic and can cause significant grief. The ability to perform independent activities like reading books or driving can be greatly impacted by vision loss, and this may be difficult to accept.

Fortunately, there are technological improvements alongside medical advancements that are making life easier for people who struggle with low vision.

Treatment and Assistance for Low Vision

Low vision that occurs past childhood is most often a symptom of aging, although if you experience sudden changes in your vision, you should contact an ophthalmologist or optometrist and a physician immediately.

If you have progressive low vision, your eye doctor will monitor the condition and manage your sight for as long as possible with corrective lenses like glasses or contact lenses. You may also benefit from refractive surgeries like LASIK, but these are not appropriate for everyone.

If you begin to struggle with reading, driving, or shopping in normal conditions with corrective wear, your optometrist may refer you to vision rehabilitation. This treatment involves a team that will assess the vision you have left and how you can best use it to navigate the world, including to accomplish your personal goals. For example, you may receive magnifiers and learn ways to reduce glare and increase contrast. You may also benefit from better lighting in your home.

Large-print books, audiobooks, video magnifiers including smartphone apps, and special telephones, thermostats, watches, and remote controls all exist to help people with low vision navigate the world safely. As digital technology progresses to different devices like smart watches and other small handhelds, there are better ways for you to continue your lifestyle while managing low vision.

References

Low Vision. American Optometric Association (AOA).

What Is Low Vision? (June 2017). All About Vision.

Low Vision and Legal Blindness Terms and Descriptions. American Foundation for the Blind (AFB).

Low Vision Symptoms. (February 25, 2019). American Academy of Ophthalmology (AAO).

Low Vision Diagnosis and Treatment. (February 25, 2019). American Academy of Ophthalmology (AAO).

Low Vision Rehabilitation Teams and Services. (February 25, 2019). American Academy of Ophthalmology (AAO).

Low Vision Assistive Devices. (February 25, 2019). American Academy of Ophthalmology (AAO).