Blindness Causes
The causes of loss of vision are extremely varied and range from conditions affecting the eyes to conditions affecting the visual processing centers in the brain. mpaired vision becomes more common with age. Common causes of vision loss in the elderly include diabetic retinopathy, glaucoma, age-related macular degeneration, and cataracts.
What is 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.
When is one considered legally blind?
Legal blindness is not a medical term. It is defined by lawmakers in nations or states in order to either limit allowable activities, such as driving, by individuals who are "legally blind" or to provide preferential governmental benefits to those people in the form of educational services or monetary assistance. Under the Aid to the Blind program in the Social Security Act passed in 1935, the United States Congress defined legal blindness as either central visual acuity of 20/200 or less in the better eye with corrective glasses or central visual acuity of more than 20/200 if there is a visual field defect in which the peripheral field is contracted to such an extent that the widest diameter of the visual field subtends an angular distance no greater than 20 degrees in the better eye. Blindness in one eye is never defined as legal blindness if the other eye is normal or near-normal.
It is estimated that more than 1 million people in the United States meet the legal definition of blindness.
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.
People often say, "I am 'blind as a bat' without my glasses." All bat species have eyes, and most have excellent vision at night but not in daylight. More importantly, the term blindness means the inability to see despite wearing glasses. Anyone who has access to glasses and sees well with the glasses cannot be termed blind.
What causes blindness?
The many causes of blindness differ according to the socioeconomic condition of the nation being studied. In developed nations, the leading causes of blindness include ocular complications of diabetes, macular degeneration, glaucoma, and traumatic injuries. In third-world nations where 90% of the world's visually impaired population lives, the principal causes are infections, cataracts, glaucoma, injury, and inability to obtain any glasses. In developed nations, the term blindness is not used to describe those people whose vision is correctable with glasses.
Infectious causes in underdeveloped areas of the world include trachoma, onchocerciasis (river blindness), and leprosy. The most common infectious cause of blindness in developed nations is herpes simplex. Other causes of blindness include vitamin A deficiency, retinopathy of prematurity, blood vessel diseases involving the retina or optic nerve including stroke, infectious diseases of the cornea or retina, 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.
What are risk factors for blindness?
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.
What are signs and symptoms of blindness?
All people who are blind or have visual impairment have the common symptom of difficulty seeing. People with similar levels of visual loss may have very different responses to that symptom. If one is born blind, there is much less adjustment to a non-seeing world than there is for people who lose their vision late in life, where there may be limited ability to cope with that visual loss. Support systems available to individuals and their psychological makeup will also modify the symptom of lack of sight. People who lose their vision suddenly, rather than over a period of years, also can have more difficulty adjusting to their visual loss.
Associated symptoms, such a discomfort in the eyes, awareness of the eyes, foreign body sensation, and pain in the eyes or discharge from the eyes may be present or absent, depending on the underlying cause of the blindness.
A blind person may have no visible signs of any abnormalities when sitting in a chair and resting. However, when blindness is a result of infection of the cornea (the dome in front of the eye), the normally transparent cornea may become white or gray, making it difficult to view the colored part of the eye. In blindness from cataract, the normally black pupil may appear white. Depending on the degree of blindness, the affected individual will exhibit signs of visual loss when attempting to ambulate. Some blind people have learned to look directly at the person they are speaking with, so it is not obvious they are blind.
What specialists treat blindness?
Ophthalmology is the specialty of medicine that deals with diagnosis and medical and surgical treatment of eye disease. Therefore, ophthalmologists are the specialists who have the knowledge and tools to diagnose the cause of blindness and to provide treatment, if possible.
How do health care professionals diagnose blindness?
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.
What are treatments for blindness?
The treatment of visual impairment or blindness depends on the cause. In third-world nations where many people have poor vision as a result of a refractive error, merely prescribing and giving glasses will alleviate the problem. Nutritional causes of blindness can be addressed by dietary changes. There are millions of people in the world who are blind from cataracts. In these patients, cataract surgery would, in most cases, restore their sight. Inflammatory and infectious causes of blindness can be treated with medication in the form of drops or pills. Corneal transplantation may help people whose vision is absent as a result of corneal scarring.
What is the prognosis for blindness?
The prognosis for blindness is dependent on its cause. In patients with blindness due to optic-nerve damage or a completed stroke, visual acuity can usually not be restored. Patients with long-standing retinal detachment in general cannot be improved with surgical repair of their detachment. Patients who have corneal scarring or cataract usually have a good prognosis if they are able to access surgical care of their condition.
Is blindness preventable?
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.
Medically Reviewed on 11/14/2017
References
American Academy of Ophthalmology. "Eye Health Statistics at a Glance." <http://www.aao.org/newsroom/upload/Eye-Health-Statistics-April-2011.pdf>.
Switzerland. World Health Organization. "Visual Impairment and Blindness." Oct. 2017. <http://www.who.int/mediacentre/factsheets/fs282/en/>.
Read more here:
Blindness Symptoms, Treatment & Types
- World report on vision - World Health Organization (WHO) - November 16th, 2024
- Eye care, vision impairment and blindness programme - November 16th, 2024
- $45,000 Raised to benefit SGML Eye Hospital near Ujjain, India for rural and underserved population to prevent blindness - The Indian Panorama - November 16th, 2024
- Foundation Fighting Blindness Funds 35 New Research Grants in FY2024, Renames Key Program to Honor Former Board Chair - PR Newswire - November 16th, 2024
- Fighting blindness with Love Tags - WFLA - November 16th, 2024
- Woman With Rare Disease Waiting For Blindness To 'Cure' Hallucinations - News18 - November 16th, 2024
- Color Blindness Market Is Anticipated To Grow In A Promising - openPR - November 16th, 2024
- Towards a truer vision of broader inclusivity - The New Indian Express - November 16th, 2024
- WHO launches first World report on vision - October 22nd, 2024
- Eye health, vision impairment and blindness - World Health Organization ... - October 22nd, 2024
- Onchocerciasis - World Health Organization (WHO) - October 22nd, 2024
- Eye care, vision impairment and blindness: Refractive errors - October 22nd, 2024
- Blindness Prevention and Control - World Health Organization (WHO) - October 22nd, 2024
- Onchocerciasis (river blindness) - World Health Organization (WHO) - October 22nd, 2024
- Trachoma - World Health Organization (WHO) - October 22nd, 2024
- Blindness is not a curse to be broken - America: The Jesuit Review - October 22nd, 2024
- Alfred University gives away two pairs of EnChroma glasses for color blindness - www.alfred.edu - October 22nd, 2024
- All the Plants We Cannot See - The Revelator - October 22nd, 2024
- ASI Power Summit 2024: How Blindness Helped Michael Hingson Survive the 9/11 Attacks - ASI - October 22nd, 2024
- People with blindness and their allies rally outside Uber and Lyft over ride denials - The Mercury News - October 22nd, 2024
- New Study Links Ozempic to BlindnessBut They Can Actually Protect Your Eyes - First For Women - October 22nd, 2024
- Conservatives Use Trump Assassination Attempt to Target Women in Anti-Diversity War - The American Prospect - October 22nd, 2024
- Google AI to help detect preventable blindness in India and Thailand - Techloy - October 22nd, 2024
- How blindness drove man to seek, spread solutions - The Star Kenya - October 22nd, 2024
- As Glaucoma Rates Soar, Heres What to Know About This Progressive Condition - News Reports - October 22nd, 2024
- Heres how you can spot and prevent cataracts from causing blindness - SNL24 - October 22nd, 2024
- What Are the 7 Causes of Blindness? - Healthline - June 2nd, 2024
- Blindness and Low Vision | American Foundation for the Blind - June 2nd, 2024
- Eye care, vision impairment and blindness - World Health Organization (WHO) - October 27th, 2023
- CHOROIDEREMIA RESEARCH FOUNDATION EXPANDS RESEARCH SUPPORT INTO NONSENSE MUTATIONS OF A RARE INHERITED RETINAL - EIN News - May 1st, 2023
- Chennai eye hospital ties up with Iceland firm to adopt mathematical algorithm to predict diabetic retinopathy - The Hindu - April 23rd, 2023
- Drug-Resistant Bacteria Tied to Eyedrops Can Spread Person to Person ... - April 7th, 2023
- Prevention of Blindness Week 2023: Mumbai experts explain why you should be concerned about glaucoma and the need for regular eye checkups -... - April 7th, 2023
- Childhood blindness - Wikipedia - February 24th, 2023
- FDA Approves Syfovre (pegcetacoplan injection) for the Treatment of ... - February 24th, 2023
- Human mini brains illuminate path to curing blindness - February 16th, 2023
- Raymond V. Gilmartin: Man with a global vision - February 16th, 2023
- Why Are People So Mad About MrBeast's Blindness Video? - February 16th, 2023
- This heartwarming video of a colorblind boy seeing color for the first time will make you cry - Indiatimes.com - February 16th, 2023
- Blindness (Vision Impairment): Types, Causes and Treatment - February 8th, 2023
- CDC urges people to stop using brand of artificial tears linked to ... - February 8th, 2023
- Health News Roundup: U.S. FDA says India-made eye drop linked to some infections, blindness and one death; China records 3,278 COVID-related deaths... - February 8th, 2023
- I had two strokes at 29 and gone blind -I've been accused of faking my sight loss - Daily Mail - February 8th, 2023
- Blindness and vision impairment - World Health Organization - January 23rd, 2023
- Recovery from blindness - Wikipedia - January 23rd, 2023
- Colour blindness tests, juggling, avoiding glare: A hockey goalkeepeers quest to train his biggest weapon, eyes - The Indian Express - January 23rd, 2023
- But Did You See the Gorilla? The Problem With Inattentional Blindness ... - October 15th, 2022
- Canadians unaware of diseases that lead to blindness, survey says - CTV News Northern Ontario - October 15th, 2022
- A Review of Corneal Blindness: Causes and Management - Cureus - October 15th, 2022
- A cure for blindness may be first product made in space - Freethink - October 15th, 2022
- Is MrBeast trying to cure 1000 people's blindness? - indy100 - October 15th, 2022
- Early detection and management is the key to prevent glaucoma related blindness: Experts - Express Healthcare - October 15th, 2022
- As World Sight Day Nears, River Blindness is Fading - SaportaReport - October 15th, 2022
- Tears of happiness: How curing blindness in Dolakha saved a girls future - City A.M. - October 15th, 2022
- World Sight Day: Orbis, UC Davis team up to train eye care teams from Latin America to fight avoidable blindness - Ophthalmology Times - October 15th, 2022
- Juan Williams: The GOPs epidemic of intentional blindness - The Hill - October 15th, 2022
- Charles pays tribute to Malawi's elimination of disease causing blindness - Express & Star - October 15th, 2022
- Coping with calamity: Former NYT columnist Frank Bruni on blindness and vision, at Morristown book fest keynote - Morristown Green - October 15th, 2022
- Sighting solutions in a world of vision for weavers - The New Indian Express - October 15th, 2022
- Blindfold run raises $40,000 for the MUHC Foundation to support glaucoma care at the MUHC - StreetInsider.com - October 15th, 2022
- MacKenzie Scott Donates $15M to Address the Eyecare Needs of the Impoverished - InvisionMag - October 15th, 2022
- Astellas and MBC BioLabs Announce Astellas Future Innovator Prize to Help Biotech Start-ups Accelerate Early Drug Discovery and Research Efforts -... - September 20th, 2022
- Treating cataracts before 'critical age' imperative FBC News - FBC News - September 20th, 2022
- GenSight Biologics to Present at Upcoming Industry and Investor Conferences - Business Wire - September 20th, 2022
- Ashton Kutcher battled vasculitis causing blindness, loss of hearing. Know all about the rare condition - India TV News - August 11th, 2022
- Prevent Blindness Is Recognized as a Healthy People 2030 Champion for Supporting the Initiative's Vision - Vision Monday - August 11th, 2022
- Researchers make progress toward a stem cellbased therapy for blindness - Ophthalmology Times - August 11th, 2022
- The strategic blindness of Israel's caretaker government - JNS.org - August 11th, 2022
- UND professor carries the torch for UND studies of visual impairment and blindness - Grand Forks Herald - August 11th, 2022
- Karan Nagrani is using social media to raise awareness about the 'spectrum of blindness' - ABC News - August 11th, 2022
- Vision impairment and blindness related to NCDs: Fong - FBC News - August 11th, 2022
- Strategic blindness of caretaker government - The Jewish Star - August 11th, 2022
- Massachusetts woman blinded by attack working to help others regain sight - WCVB Boston - August 11th, 2022
- Persuasion Film Review: Is Heterogeneous Casting Race-Inclusionary Or Escapist? - Feminism In India - August 11th, 2022
- Is It Time To Start Using Race And Gender To Combat Bias In Lending? - Forbes - August 11th, 2022
- The journey of Kali Yugi started with the mistake of objectives! - Youthistaan - August 11th, 2022
- A 50-State Review of Access to State Medicaid Program Information for People with Limited English Proficiency and/or Disabilities Ahead of the PHE... - August 11th, 2022
- iHealthScreen Completed Prospective Trial of AI-Based Tool for Age-Related Macular Degeneration (AMD) Screening and Submitting the Results to FDA for... - August 11th, 2022
- Vitamin B12: Why You Need It & Foods To Increase Your Vitamin B12 Intake - NDTV - August 11th, 2022
- Jack Levine: Remembering a dad who proved that even in blindness, there can be vision - The Florida Times-Union - June 26th, 2022