Low Vision

What is low vision?

Low vision is a permanent visual impairment that you can’t correct with glasses, contacts or surgery. Most eye doctors define low vision as moderate to severe visual impairment — enough to inhibit your everyday activities, like driving and reading.

Terms like “partially sighted” and “legally blind” fall under the larger heading of low vision. But these terms also have more specific meanings. In the U.S., these refer to whether you qualify for special education or disability services for visual impairment.

Low vision may involve a variety of different types of visual impairment; not just nearsightedness or farsightedness, but also peripheral vision loss, a blind spot or blurred vision. You might have OK vision in some ways but still have low vision overall.

Low vision isn’t total blindness — some vision remains. Vision rehabilitation services help people with low vision make the most of what they’ve got. A specialist can help connect you with low vision aids and assistive technology to make your life easier.

What qualifies as low vision on a visual acuity test?

The standard visual acuity test in the U.S. is the Snellen eye chart. It measures the clarity of your vision at a distance of 20 feet from an object. If you have 20/20 vision, which is the average score, it means you can see an object clearly from 20 feet away.

If your score is 20/70, it means that your vision at 20 feet is like normal vision at 70 feet. The World Health Organization (WHO) classifies this score as moderate visual impairment or moderate low vision. A score of 20/200 or above qualifies as severe low vision.

But this isn’t the only score eye specialists consider. Other types of tests measure other aspects of your vision. For example, a visual field test measures your range of vision from side to side. Having a visual field of 20 degrees or less also qualifies as low vision.

Some people have low scores on vision tests, but they’re able to correct their impairment with glasses, contacts or surgery. If these treatments make your test scores go up, you don’t have low vision. Low vision is a condition you have even with your glasses on.

What are the signs and symptoms of low vision?

Low vision can manifest in different ways for different people.

You might have a loss of:

• Central vision: The ability to see what’s directly in front of you.
• Peripheral vision: The ability to see out of the sides of your eyes.
• Depth perception: The ability to judge the distance between objects.
• Contrast sensitivity: The ability to distinguish objects in the foreground from objects of the same shade in the background.
• Night vision: The ability to see at night or in low light.
• Glare resistance: The ability to function in bright light.

You might have difficulties with:

• Reading.
• Driving.
• Cooking.
• Classroom learning.
• Watching TV or videos.
• Using a computer.
• Recognizing people’s faces.
• Getting around, especially in unfamiliar places.

Signs of low vision in children might include:

• Frequently bumping into things.
• Holding objects very close to their face.
• Frequent squinting or blinking.
• Frequently shutting or covering one eye.
• Eyes that flutter or dance.
• Eyes that don’t point the same way.
• Pupils of different sizes.
• Pupils that look gray or white.

Side effects of permanent vision impairment can include:

• Reduced physical and social activity.
• Loss of independence or employment.
• Hallucinations (Charles Bonnet syndrome).
• Anxiety or depression.

What causes low vision?

Causes of low vision include acquired diseases, injuries and congenital (birth) defects.

Some of the most common causes include:

• Macular degeneration. This condition causes a gradual loss of central vision. You might develop a blurry or blind spot in your central visual field. It commonly affects people older than 50.
• Cataracts. Cataracts are another common age-related eye condition. A cataract is a cloud on your eye lens. Cataract surgery can often remove it, but not everyone is a candidate for surgery.
• Glaucoma. Glaucoma is a progressive condition that damages your optic nerve. It usually affects your peripheral vision and night vision first. Without treatment, it can do irreversible damage.
• Diabetes-related retinopathy. This condition causes blood vessels in your eye to leak fluids, which build pressure against your retina and damage it over time. It’s a complication of diabetes.
• Retinopathy of prematurity. Babies born pre-term and treated with incubation can develop abnormal blood vessels in their retinas. In a minority of cases, these can cause lasting damage.
• Amblyopia (lazy eye). Amblyopia is a congenital defect that causes blurry vision in one eye. As your child’s brain relies more on the good eye and ignores the bad eye, that eye begins to drift.

Other causes include:

• Refractive errors. Refractive errors affect the shape of your eye, causing nearsightedness or farsightedness. They’re correctable, but if they go untreated, they’ll continue to worsen.
• Trachoma. Trachoma is a bacterial infection that can irritate and damage your eyes. It’s a leading cause of vision loss and blindness worldwide, especially in less developed countries.
• Strabismus (misaligned eyes). Strabismus is a problem with the muscles that control your eye movements and eye alignment. It usually begins to appear in infancy or early childhood.
• Nystagmus. This condition causes rapid, uncontrollable eye movements that may make it impossible to focus your vision. It can be present at birth or acquired later in adulthood.
• Retinitis pigmentosa. Retinitis pigmentosa describes a group of inherited eye diseases that prevent your retina from working properly. Different genetic mutations can cause it.
• Hypertensive retinopathy. Chronic high blood pressure can disrupt the blood flow to your organs, including your retinas. Vision loss may be your first symptom of blood flow problems.
• Retinal detachment. This painless but serious condition causes your retina to detach from the tissues that support it, losing its blood supply. It can cause sudden and permanent vision loss.
• Optic atrophy. Optic atrophy causes your optic nerve to gradually deteriorate (waste away). A variety of conditions can cause it, including injuries, infections and blood flow problems.
• Eye injuries. A traumatic injury to your eye can cause lasting damage, especially if it isn’t recognized or treated right away. Pay attention if you have vision problems after an injury.
• Brain injuries. A traumatic head injury or stroke may cause brain damage that affects your vision. You might notice vision problems along with symptoms like headaches and dizziness.
• Vitamin A deficiency. Vitamin A is crucial to your vision. If you don’t get enough from your diet, or your body can’t absorb enough, it can cause vision loss. Night blindness is the first symptom.
• Eye cancer. All forms of eye cancer are very rare, but they can cause vision loss. Treatments to remove eye cancer can also cause vision loss, either by damaging or removing parts of your eye.

How is low vision diagnosed?

An ophthalmologist can diagnose your visual impairment, using a variety of vision tests. They’ll tell you what the issue is, how severe it is and if it’s treatable or not. If it’s moderate to severe, irreversible and significantly impacts your life, they’ll diagnose low vision.

Receiving this diagnosis can be difficult, especially if you weren’t aware that you were at risk of irreversible vision loss. You’ll probably have a series of reactions, from shock and bewilderment to numbness, denial, anger or grief. These are all natural reactions.

How do eye specialists treat low vision?

When you see an optometrist specializing in low vision, they’ll give you a special kind of exam called a low vision exam. They’ll begin by taking a complete history of your eye health, and then ask about how your condition is currently affecting your life.

They’ll ask you how low vision affects your:

• School or work.
• Reading and computer use.
• Driving.
• Functioning in the kitchen.
• Facial recognition.
• Ability to travel.
• Hobbies and leisure activities.
• Mood and social life.

The provider will also examine your eyes and vision to look for any changes in your condition. They’ll use special low vision test charts to evaluate your visual acuity.

They might also need to check your:

• Field of vision.
• Eye muscle function.
• Glare sensitivity.
• Contrast sensitivity.
• Night vision.
• Color vision.
• Depth perception.
• Reading ability.

Based on the results of your exam, a low vision specialist will design a personalized treatment plan that addresses your specific difficulties and needs. They’ll offer resources and recommendations to help you adapt and optimize your quality of life.

Vision rehabilitation

Treatment for low vision is called vision rehabilitation. The goal of the treatment is to maximize your vision as much as possible and otherwise help you live as independently as possible with the vision you have. This may involve a wide variety of resources.

Your plan might include:

Low vision aids and devices

You might benefit from:

• A prescription for glasses or contact lenses.
• Optical magnifiers or telescopes.
• Electronic magnifiers and screen readers.
• Large print and high contrast products.
• Voice-to-text and audio reading technology.
• Audible home devices.

Practical training and support

You might also benefit from:

• Occupational therapy to learn new ways to perform tasks.
• A mobility specialist to help you learn to get around.
• A rehabilitation instructor to teach you independent living skills.
• Special education or vocational services.
• Counseling or psychotherapy to maintain your mental health.
• Support groups that connect you with others living with low vision.

Can I prevent permanent vision loss?

The best way to prevent permanent vision loss is to keep up with your regular eye exams and see your provider right away if you notice anything unusual. While not all causes of low vision are preventable, many are treatable if you catch them early enough.

How will I cope with low vision?

Not everyone with low vision bothers with rehabilitation services, but most people could benefit a lot from them. From practical tools, tips and tricks to social and emotional support systems, there’s a wealth of resources out there to take advantage of.

Adapting to a disability isn’t easy, but it’s easier if you don’t try to do it alone. Remember, no matter what your challenges are, someone else out there has already faced them. Others have found solutions and ways of coping that they can pass on to you.

Can I receive disability benefits for low vision?

You may be eligible for disability benefits, based on your specific diagnosis, your financial position and other factors. Different governments have different criteria for receiving benefits. Specialists on your visual rehabilitation team can help you apply.

What is ‘partially sighted’?

Most people use “partially sighted” in a general, nonspecific way, meaning somewhat visually impaired. But occasionally, it means something more specific. In these cases, it seems to mean the same thing as moderate low vision (visual acuity of 20/70 or worse).

In the U.K., you can register with the government as “partially sighted” to receive certain benefits. If you have low vision, you qualify as “partially sighted.” Within U.S. educational systems, “partially sighted” might mean you’re eligible for special education services.