Blindness is the inability to see anything, even light. If you are partially blind, you have limited vision. Complete blindness means that you cannot see at all and are in total darkness. Legal blindness refers to vision that is highly compromised: What a person with healthy eyes can see from 200 feet away, a legally blind person can see only from 20 feet away.
If you suddenly lose the ability to see, seek medical attention right away. Go to the emergency room for treatment. Do not simply wait for your vision to return. Immediate treatment increases the chances of restoring your vision, depending on the cause of your blindness. Treatment may involve surgery or medication.
What Are the Types of Blindness?
Total blindness means that you cannot see anything. If you have partial blindness, you may suffer from blurry vision or the inability to distinguish the shapes of objects, depending on the cause of your vision impairment.
What Causes Blindness?
The following eye diseases and conditions can cause blindness:
- Glaucoma refers to four different eye conditions that damage the optic nerve that carries visual information to your brain.
- Macular degeneration destroys the part of your eye that enables you to see details. It usually affects older adults.
- Cataracts cause cloudy vision and are more common in older people.
- A lazy eye can make it difficult to see details and may lead to vision loss.
- Optic neuritis is inflammation that can cause temporary or permanent vision loss.
- Retinitis pigmentosa refers to retina damage, but leads to blindness only in rare cases.
- Tumors that affect the retina or optic nerve can also cause blindness.
If you suffer from diabetes or have a stroke, blindness is a potential complication. Birth defects, eye injuries, and complications from eye surgery are other common causes of blindness.
Who Is at Risk for Blindness?
The following categories of people are at risk for blindness:
- people with eye diseases, such as macular degeneration and glaucoma
- people with diabetes
- stroke victims
- eye surgery patients
- people who work with or near sharp objects or toxic chemicals
- premature babies
What Are the Symptoms of Blindness?
If you are completely blind, you can see nothing. If you are partially blind, you might experience the following symptoms:
- cloudy vision
- the inability to see shapes
- seeing only shadows
- poor night vision
- tunnel vision
Blindness in Infants
A child’s visual system begins to develop in the womb, but will not be fully formed until about 2 years of age. By 6 to 8 weeks of age, a baby should be able to fix his or her gaze on an object and follow its movement. By 4 months of age, the child’s eyes should be properly aligned (not turned inward or outward).
A pediatrician will screen your baby for eye problems shortly after birth. At 6 months of age, you should have an eye doctor or pediatrician check your child again for visual acuity, focus, and eye alignment. The doctor will look at your baby’s eye structures and see whether the baby can follow a light or colorful object with his or her eyes.
The following conditions can cause vision impairment or blindness in infants:
- infections, such as pink eye
- blocked tear ducts
- strabismus (crossed eyes)
- amblyopia (a lazy eye)
- ptosis (a droopy eyelid)
- congenital glaucoma
- retinopathy of prematurity (when the blood vessels that supply the retina are not fully developed in premature babies)
- visual inattention (delayed development of the child’s visual system)
Your child should be able to pay attention to visual stimuli by 6 to 8 weeks of age. If your child does not react to light shining in his or her eyes or focus on colorful objects by 2 to 3 months of age, or if you notice crossed eyes or any other symptoms of impaired vision, have your child’s eyes examined right away.
Symptoms of visual impairment in young children include:
- constant eye rubbing
- extreme sensitivity to light
- poor focusing
- chronic eye redness
- chronic tearing of the eyes
- a white instead of a black pupil
- poor visual tracking (following an object with the eyes)
- abnormal eye alignment or movement (after 6 months of age)
How Is Blindness Diagnosed?
A thorough eye exam by an optometrist will help to determine the cause of your blindness or partial loss of vision. Eye doctors administer a series of tests that measure the clarity of your vision, the function of your eye muscles, and how your pupils react to light. The eye doctor will examine the general health of your eyes using a slit lamp, which is a low-power microscope paired with a high-intensity light.
How Is Blindness Treated?
In some cases of vision impairment, eyeglasses, surgery, or medication may help to restore your vision.
If you experience partial blindness that cannot be corrected, treatment usually involves guidance on how to function with limited vision. For example, you can use a magnifying glass to read, increase the text size on your computer, and use audio clocks and audiobooks.
Complete blindness requires approaching life in a new way and learning new skills, including:
- learning to read Braille
- using a seeing-eye dog
- memorizing the phone keypad
- organizing your home so you can find things easily
- folding money in distinct ways to distinguish bill amounts
- installing handrails in your bathroom
What Is the Long-Term Outlook?
The long-term outlook for restoring vision and slowing vision loss is better when treatment is preventive and is sought immediately. Cataracts can be treated effectively with surgery and do not necessarily result in blindness. Early diagnosis and treatment is also important in cases of glaucoma and macular degeneration to help slow down or stop vision loss.
How Can Blindness Be Prevented?
To help prevent vision loss, get regular eye examinations to detect any eye diseases. If you are diagnosed with certain eye conditions, such as glaucoma, treatment with medication can help to prevent blindness.