Blindness

Blindness refers to a lack of vision. It can be a symptom of various eye diseases you develop or disorders you've had since birth. You should seek immediate medical attention if you experience a new loss of sight.

This article discusses types of blindness, symptoms related to blindness, potential causes, and treatments.

Symptoms of Blindness

The symptoms of blindness depend on the type of blindness an individual has.

With complete blindness, symptoms include:

• No perception of light
• Vision that can't be corrected with contact lenses or glasses

In most states, legal blindness is vision that is worse than 20/200, even when using glasses or contact lenses. The definition of legal blindness helps determine if a person is eligible for disability benefits.

Another type of blindness is called night blindness. This refers to vision problems at night or in dark environments. Symptoms of night blindness include:

• Poor vision at night
• Poor vision in dim lighting
• Vision that is particularly bad after going from a brightly lit area to a dark area

Color blindness, another type of blindness, refers to an inability to distinguish between specific colors. Symptoms include:

• Trouble perceiving the brightness of colors
• An inability to distinguish between shades of similar colors (this occurs most frequently with red and green or blue and yellow)

Causes of Blindness

The most common causes of blindness in the United States are age-related macular degeneration (AMD), cataract, and diabetic retinopathy.

Age-Related Macular Degeneration

AMD is an eye disorder that is more common with age and affects your central vision. Central vision is what you use for everyday tasks like driving and reading. Although most people with AMD will not go blind from it, it is the leading cause of vision loss among those who are 50 or older.

Cataract

A cataract is a clouding of the lens in the eye. Cataracts become more common with age, although they can occur at any age and even be present at birth. Cataracts are one of the leading causes of blindness around the world.

Diabetic Retinopathy

Diabetic retinopathy occurs in people with diabetes and results from damage to blood vessels in the retina, the light-sensitive tissue located in the back of the eye. Diabetic retinopathy is the leading cause of blindness among American adults.

Other Causes

In addition to AMD, cataracts, and diabetic retinopathy, there are many other potential causes for blindness, including:

• Glaucoma
• Eye injury
• Disorders that are present at birth

What Medications Can Cause Blindness?

Many medications can affect your vision. Some drugs increase the risk for angle-closure glaucoma due to a narrowing of the eye's drainage angle. An acute angle-closure attack can affect your vision suddenly and is a medical emergency.

Medications that increase the risk of this type of attack include:

• Anticholinergics, which include some of the drugs that treat allergies, depression, and heart disease
• Drugs with ephedrine
• Drugs with sulfonamide
• Oral steroids

Acute angle-closure attacks are more prevalent in females, people of Asian descent, and those with a family history of angle-closure glaucoma.

Glaucoma is another cause of blindness if left untreated. If you have glaucoma, it's important to discuss medication use with your healthcare providers to help avoid drugs that can make glaucoma worse.

How to Treat Blindness

There are emerging treatments that help some specific types of blindness, such as blindness caused by the genetic disorder Leber congenital amaurosis. Yet the majority of treatments for vision loss focus on preserving any remaining vision you have. These treatments vary widely depending on what is causing the blindness.

Age-Related Macular Degeneration

The most common treatment for AMD is a class of drugs called anti-vascular endothelial growth factors (VEGF). These are injected into the eye. Anti-VEGF drugs won't restore the vision that you've lost, but they can help maintain what vision you still have. If you have AMD in one eye but not the other, a special vitamin and mineral supplement called AREDS 2 may help slow down AMD in the other eye.

Cataract

Cataracts are most frequently treated with surgery that removes the cloudy lens and replaces it with an artificial one. Cataract surgery cures the vision loss the cataract causes, although you may still need to wear glasses for some of your vision-related tasks.

Diabetic Retinopathy

Diabetic retinopathy treatment includes anti-VEGF drug injections, lasers, and surgery. The treatments won't restore your vision, but they may prevent further vision loss. You should also do what you can to control your diabetes to help slow diabetic retinopathy.

Complications and Risk Factors Associated With Blindness

Risk factors associated with blindness depend on the cause.

Risk factors for age-related macular degeneration include:

• Being age 50 or older
• Having high blood pressure
• Having a diet high in saturated fat
• Smoking

Risk factors for cataracts include:

• Age
• Diabetes
• Excessive exposure to the sun without the use of sunglasses
• Having an eye injury or previous eye surgery
• Smoking

Risk factors for diabetic retinopathy include:

• Getting pregnant when you have diabetes
• Uncontrolled diabetes

Are There Tests to Diagnose the Cause of Blindness?

To diagnose what is causing blindness, an eye doctor will conduct an eye exam. Some functions of an eye exam include examining and measuring:

• How well you see
• Your eye's anatomy (including the back and front of the eye)
• How your pupils respond to light
• Your eye muscles

Your eye doctor will perform other, more detailed tests as needed to pinpoint the cause of blindness.

When to See a Healthcare Provider

Sudden vision loss is rarely painful, so you can't rely on pain as a sign that your vision needs attention. Seek immediate medical care if you suddenly lose vision in one or both eyes.

Summary

Complete blindness means a lack of vision and no perception of light. There are other forms of blindness, including legal blindness, night blindness, and color blindness. The most common causes of blindness in the United States are AMD, cataracts, and diabetic retinopathy. Glaucoma can also lead to blindness if left uncontrolled.

Treatments for the most common causes of blindness help preserve remaining sight but do not restore vision loss. Older age and smoking are risk factors for the most common causes of blindness in the United States. Having diabetes raises the risk of cataracts and diabetic retinopathy.

You should see a healthcare provider immediately if you have sudden vision loss.