Blindness

Blindness is defined as the state of being sightless. A blind individual is unable to see. In a strict sense the word "blindness" denotes the inability of a person to distinguish darkness from bright light in either eye. The terms blind and blindness have been modified in our society to include a wide range of visual impairment. Blindness is frequently used today to describe severe visual decline in one or both eyes with maintenance of some residual vision.

Vision impairment, or low vision, means that even with eyeglasses, contact lenses, medicine, or surgery, someone doesn't see well. Vision impairment can range from mild to severe. Worldwide, between 300 million-400 million people are visually impaired due to various causes. Of this group, approximately 50 million people are totally blind. Approximately 80% of blindness occurs in people over 50 years of age.

Blindness facts

  • Blindness is strictly defined as the state of being totally sightless in both eyes. A completely blind individual is unable to see at all. The word blindness, however, is commonly used as a relative term to signify visual impairment, or low vision, meaning that even with eyeglasses, contact lenses, medicine or surgery, a person does not see well. Vision impairment can range from mild to severe.
  • Worldwide, between 300 million and 400 million people are visually impaired due to various causes. Of this group, approximately 50 million people are totally blind, unable to see light in either eye. Eighty percent of blindness occurs in people over 50 years old.
  • Common causes of blindness include diabetes, macular degeneration, traumatic injuries, infections of the cornea or retina, glaucoma, and inability to obtain any glasses.
  • Less common causes of blindness include vitamin A deficiency, retinopathy of prematurity, vascular disease involving the retina or optic nerve including stroke, ocular inflammatory disease, retinitis pigmentosa, primary or secondary malignancies of the eye, congenital abnormalities, hereditary diseases of the eye, and chemical poisoning from toxic agents such as methanol.
  • Temporary blindness differs in causes from permanent blindness.
  • The diagnosis of blindness is made by examination of all parts of the eye by an ophthalmologist.
  • The universal symptom of blindness or visual impairment is difficulty with seeing. People who lose their vision suddenly, rather than over a period of years, are more symptomatic regarding their visual loss.
  • The treatment of blindness depends on the cause of blindness.
  • The prognosis for blindness is dependent on its cause.
  • Legal blindness is defined by lawmakers in nations or states in order to either limit allowable activities, such as driving, of individuals who are "legally blind" or to provide preferential governmental benefits to those people in the form of special educational services, assistance with daily functions or monetary assistance. It is estimated that approximately 700,000 people in the United States meet the legal definition of blindness.
  • In most states in the United States, "legal blindness" is defined as the inability to see at least 20/200 in either eye with best optical correction.
  • Between 80%-90% of the blindness in the world is preventable through a combination of education, access to good medical care, and provision of glasses.
  • Patients who have untreatable blindness require reorganization of their habits and re-education to allow them to do everyday tasks in different ways. In the United States and most other developed nations, financial assistance through various agencies can pay for the training and support necessary to allow a blind person to function.
  • There are countless individuals with blindness, who, despite significant visual handicaps, have had full lives and enriched the lives of those who have had contact with them.

What are the different types of blindness?

Color blindness is the inability to perceive differences in various shades of colors, particularly green and red, that others can distinguish. It is most often inherited (genetic) and affects about 8% of males and under 1% of women. People who are color blind usually have normal vision otherwise and can function well visually. This is actually not true blindness.

Night blindness is a difficulty in seeing under situations of decreased illumination. It can be genetic or acquired. The majority of people who have night vision difficulties function well under normal lighting conditions; this is not a state of sightlessness.

Snow blindness is loss of vision after exposure of the eyes to large amounts of ultraviolet light. Snow blindness is usually temporary and is due to swelling of cells of the corneal surface. Even in the most severe of cases of snow blindness, the individual is still able to see shapes and movement.

No health feed found.

The following eye diseases and conditions can cause blindness:
  • Glaucoma refers to four different eye conditions that can damage your optic nerve, which carries visual information from your eyes 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. They’re more common in older people.
  • A lazy eye can make it difficult to see details. It may lead to vision loss.
  • Optic neuritis is inflammation that can cause temporary or permanent vision loss.
  • Retinitis pigmentosa refers to damage of the retina. It leads to blindness only in rare cases.
  • Tumors that affect your retina or optic nerve can also cause blindness.

Blindness is a potential complication if you have diabetes or have a stroke. Birth defects, eye injuries, and complications from eye surgery are other common causes of blindness.

Causes of Blindness in Infants

The following conditions can impair vision or cause blindness in infants:

  • infections, such as pinkeye
  • blocked tear ducts
  • cataracts
  • strabismus, or crossed eyes
  • amblyopia, or a lazy eye
  • ptosis, or a droopy eyelid
  • congenital glaucoma
  • retinopathy of prematurity, which occurs in premature babies when the blood vessels that supply their retina aren’t fully developed
  • visual inattention, or delayed development of your child’s visual system

A principal risk factor for blindness is living in a third-world nation without ready access to modern medical care. Other risk factors include poor prenatal care, premature birth, advancing age, poor nutrition, failing to wear safety glasses when indicated, poor hygiene, smoking, a family history of blindness, the presence of various ocular diseases and the existence of medical conditions including diabetes mellitus, hypertension, cerebrovascular disease, and cardiovascular disease.

If you’re completely blind, you can see nothing. If you’re partially blind, you might experience the following symptoms:

  • cloudy vision
  • an inability to see shapes
  • seeing only shadows
  • poor night vision
  • tunnel vision

Symptoms of Blindness in Infants

Your child’s visual system begins to develop in the womb, but it won’t be fully formed until about 2 years of age. By 6 to 8 weeks of age, your baby should be able to fix their gaze on an object and follow its movement. By 4 months of age, their eyes should be properly aligned and not turned inward or outward.

The symptoms of visual impairment in young children can include:

  • constant eye rubbing
  • an extreme sensitivity to light
  • poor focusing
  • chronic eye redness
  • chronic tearing from their eyes
  • a white instead of a black pupil
  • poor visual tracking, or trouble following an object with their eyes
  • abnormal eye alignment or movement after 6 months of age

Blindness is diagnosed by testing each eye individually and by measuring the visual acuity and the visual field, or peripheral vision. People may have blindness in one (unilateral blindness) or both eyes (bilateral blindness). Historical information regarding the blindness can be helpful in diagnosing the cause of blindness. Poor vision that is sudden in onset differs in potential causes than blindness that is progressive or chronic. Temporary blindness differs in cause from permanent blindness. The cause of blindness is made by a thorough examination by an ophthalmologist.

In some cases of vision impairment, one or more of the following may help to restore your vision:

  • eyeglasses
  • contact lenses
  • surgery
  • medication

If you experience partial blindness that can’t be corrected, your doctor will provide 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. For example, you may need to learn how to:

  • read Braille
  • use a guide dog
  • memorize the keypad on your phone
  • organize your home so you can find things easily
  • fold money in distinct ways to distinguish bill amounts

You may also need to have handrails installed in your bathroom.

Blindness is preventable through a combination of education and access to good medical care. Most traumatic causes of blindness can be prevented through eye protection. Nutritional causes of blindness are preventable through proper diet. Most cases of blindness from glaucoma are preventable through early detection and appropriate treatment. Visual impairment and blindness caused by infectious diseases have been greatly reduced through international public-health measures.

The majority of blindness from diabetic retinopathy is preventable through careful control of blood-sugar levels, exercise, avoidance of obesity and smoking, and emphasis on eating foods that do not increase the sugar load (complex, rather than simple carbohydrates). There has been an increase in the number of people who are blind or visually impaired from conditions that are a result of living longer. As the world's population achieves greater longevity, there will also be more blindness from diseases such as macular degeneration. However, these diseases are so common that research and treatment are constantly evolving. Regular eye examinations may often uncover a potentially blinding illness that can then be treated before there is any visual loss.

There is ongoing research regarding gene therapy for certain patients with inheritable diseases such as Leber's congenital amaurosis (LCA) and retinitis pigmentosa. Improvements in diagnosis and prevention of retinopathy of prematurity, a potentially blinding illness seen in premature babies, have made it an avoidable cause of blindness today.

Patients who have untreatable blindness need tools and help to reorganize their habits and the way in which they perform their everyday tasks. Organizations, such as the Braille Institute, offer helpful resources and support for people with blindness and for their families. Visual aids, text-reading software, and Braille books are available, together with many simple and complex technologies to assist people with severely compromised vision in functioning more effectively. In the United States and most other developed nations, financial assistance through various agencies can pay for the training and support necessary to allow a blind person to function.

John Milton and Helen Keller are well known for their accomplishments in life despite being blind. There are countless other unnamed individuals with blindness, however, who, despite significant visual handicaps, have had full lives and enriched the lives of those who have interacted with them.

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