Blindness and Vision Loss: Types, Causes, and More

Blindness is completely or severely reduced vision. Contrary to popular belief, most people who are blind have some vision—only about 15% of blindness results in total vision loss. Blindness can occur at any point in life, but it’s most common with age.

Blindness symptoms depend on the cause but typically include low vision accompanied by blurred vision, hazy or cloudy vision, and poor night vision. People may experience challenges with daily living activities such as driving, working, reading, and doing chores. 

Some people may be born blind. Blindness can also occur suddenly, such as in an accident, though it usually develops slowly. Not all blindness can be prevented, but several lifestyle modifications can greatly reduce your chances of developing the underlying conditions that cause blindness. 

There are several types of blindness, each of which describe forms of total or severe vision loss.

Total Blindness 

People with total blindness cannot see anything, including any light. Total blindness is not a common form of blindness—85% of blind people can see to some extent. 

Partial Blindness 

Individuals with partial blindness have some ability to see, but it’s greatly impaired. Glasses or contacts cannot fully correct their vision, and their low vision affects their daily life. 

Congenital or Inherited Blindness

This type of blindness describes people born blind or with eye conditions that lead to blindness in early life. Examples include retinitis pigmentosa, a condition that runs in families, in which people slowly lose their night vision and peripheral vision. 

Legal Blindness 

Blindness that qualifies for disability and other benefits in the United States is considered legal blindness. If you have a central visual acuity of 20/200 or worse in your better eye with glasses or contacts, or your visual field is restricted to 20 degrees or less in your better eye, you may qualify for legal blindness.

Not everyone who is blind has full vision loss. Most people who are blind experience a gradual loss of vision over time. Symptoms of vision loss include:

• Blurred vision
• Hazy and cloudy vision
• Poor night vision
• Wavy lines in your vision 
• Spots in your vision 
• Less vibrant color vision
• Difficulty seeing the periphery (to the sides)
• Frequently needing updated prescriptions for your glasses and contacts 
• Trouble seeing in low lighting

Most people experience some symptoms of vision loss as they get older. You may notice over time that you need reading glasses, for example. However, gradual vision loss may also be a sign of an undiagnosed health condition that can lead to blindness. That’s why it’s important to have regular eye exams.

Vision is a complex process that requires the coordination of many different parts of your eyes and brain. Diseases, structural differences, and injuries can affect this process. Causes of vision loss and blindness include:

• Diabetic retinopathy: This condition, caused by diabetes, can lead to permanent damage of the retina, which is the area in the back of your eye that translates light into signals that your brain can understand. Diabetic retinopathy is the leading cause of blindness among adults in the United States.
• Cataracts: These are cloudy areas in the lens of your eye that make focusing light on the retinas more challenging.
• Age-related macular degeneration: This age-related damage to the macula, a part of the retina, causes central vision loss (trouble seeing directly in front of you).
• Glaucoma: This eye disease damages optic nerves, which carry signals from your eyes to your brain.
• Refractive errors: This type of vision loss occurs when the shape of your eyes makes it difficult to focus light on your retinas. It causes nearsightedness and farsightedness.

These are only a few of the many causes of blindness. Although most blindness occurs with age, other forms of blindness occur during childhood, which can have a variety of causes. Blindness can also occur after a traumatic injury to the eye.

An optometrist or ophthalmologist can diagnose blindness. An optometrist is an eye doctor who specializes in routine eye exams and can diagnose and treat some eye conditions. An ophthalmologist is a medical doctor who specializes in a range of eye conditions. 

Your healthcare provider will likely conduct multiple eye tests to check your visual acuity (clarity of vision) and visual field (range of vision). They may perform additional tests, such as a retinal scan or a dilated eye exam, to better understand how your eyes work. 

Your healthcare provider will also ask about your health history, including questions about diabetes, high blood pressure, your occupation, and your smoking status. They will also ask about any family history of eye diseases or blindness.

Treatment for blindness focuses on managing the underlying cause of your vision loss. In most cases, the vision loss is permanent. However, slowing the progression of vision loss is key. Some treatments for blindness include:

• Medication for glaucoma to reduce pressure in the eye
• Managing any diabetes and high blood pressure
• Surgery for cataracts
• Fixing any nutritional deficiencies 
• Corneal transplants 

Other resources include service animals such as guide dogs. Your healthcare provider may also prescribe vision rehabilitation to help you better manage living with low vision. 

In some cases, blindness isn’t preventable. In other cases, you may be able to prevent or slow the progression of your vision loss. Getting regular eye health exams every 1-2 years is an important step you can take to catch potential causes of vision loss early.

Other prevention strategies include the following:

• Eat a well-balanced diet rich in fruits and vegetables
• Manage your blood sugar, especially if you have diabetes
• Wear sunglasses outdoors
• Maintain a healthy blood pressure
• Avoid smoking
• Wear protective eyewear at workplaces or other areas with hazards that could lead to injury

Several chronic (long-term) conditions may increase your risk of developing blindness. That’s why managing them with your healthcare provider is important in preventing blindness. These conditions include diabetes and high blood pressure. Additionally, cataracts can cause blindness if they’re not surgically removed. 

Many resources are available to help those with severe vision loss. If you’re legally blind, you may qualify for government assistance, including:

• Social Security Disability Insurance (SSDI)
• Supplemental Security Income (SSI) 
• Medicare or Medicaid

You may also be eligible for services to help with your day-to-day tasks, such as:

• Vision rehabilitation services
• Service dogs (“seeing eye dogs”)
• Mobility aids
• Assistance in school or work 

If you want to learn more about potential services, talk with your healthcare provider, human resources at work, or disability services at school. You can also learn more online from the Social Security Administration.