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Blindness: Symptoms, Causes, Risk Factors & More

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A Quiz for TeensAre You a Workaholic?How Well Do You Sleep?Tools & ResourcesHealth NewsFind a DietFind Healthy SnacksDrugs A-ZHealth A-ZConnectFind Your Bezzy CommunityBreast CancerInflammatory Bowel DiseasePsoriatic ArthritisMigraineMultiple SclerosisPsoriasisFollow us on social mediaHealthlineHealth ConditionsDiscoverPlanConnectSubscribeWhat You Need to Know About BlindnessMedically reviewed by Ann Marie Griff, O.D. — By Chitra Badii — Updated on September 5, 2019SymptomsCausesRisk factorsDiagnosisTreatmentOutlookPrevention OverviewBlindness is the inability to see anything, including light. If you’re partially blind, you have limited vision. For example, you may have blurry vision or the inability to distinguish the shapes of objects. Complete blindness means you can’t see at all. Legal blindness refers to vision that’s highly compromised. What a person with regular vision can see from 200 feet away, a legally blind person can see from only 20 feet away.Seek medical attention right away if you suddenly lose the ability to see. Have someone bring you to the emergency room for treatment. Don’t wait for your vision to return. Depending on the cause of your blindness, immediate treatment may increase your chances for restoring your vision. Treatment may involve surgery or medication. What are the symptoms of blindness?If you’re completely blind, you see nothing. If you’re partially blind, you might experience the following symptoms:cloudy visionan inability to see shapesseeing only shadowspoor night visiontunnel visionSymptoms of blindness in infants Your child’s visual system begins to develop in the womb. It doesn’t fully form 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 rubbingan extreme sensitivity to lightpoor focusingchronic eye rednesschronic tearing from their eyesa white instead of black pupilpoor visual tracking, or trouble following an object with their eyesabnormal eye alignment or movement after 6 months of age What causes blindness?The following eye diseases and conditions can cause blindness:Glaucoma refers to 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 the retina or optic nerve can also cause blindness.Blindness is a potential complication if you have diabetes or have a stroke. Other common causes of blindness include: birth defectseye injuriescomplications from eye surgeryCauses of blindness in infants The following conditions can impair vision or cause blindness in infants:infections, such as pink eyeblocked tear ductscataractsstrabismus (crossed eyes) amblyopia (lazy eye)ptosis (droopy eyelid)congenital glaucomaretinopathy of prematurity (ROP), which occurs in premature babies when the blood vessels that supply their retina aren’t fully developedvisual inattention, or delayed development of your child’s visual system Who’s at risk for blindness?The following categories of people are at risk for blindness:people with eye diseases, such as macular degeneration and glaucomapeople with diabetespeople who have a strokepeople undergoing eye surgerypeople who work with or near sharp objects or toxic chemicalspremature babies How is blindness diagnosed?A thorough eye exam by an optometrist will help determine the cause of your blindness or partial loss of vision. Your eye doctor will administer a series of tests that measure: the clarity of your visionthe function of your eye muscleshow your pupils react to lightThey’ll examine the general health of your eyes using a slit lamp. It’s a low-power microscope paired with a high-intensity light.Diagnosing blindness in infantsA pediatrician will screen your baby for eye problems shortly after birth. At 6 months of age, 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 they can follow a light or colorful object with their eyes.Your child should be able to pay attention to visual stimuli by 6 to 8 weeks of age. If your child doesn’t react to light shining in their eyes or focus on colorful objects by 2 to 3 months of age, have their eyes examined right away. Have your child’s eyes examined if you notice crossed eyes or any other symptoms of impaired vision. How is blindness treated?In some cases of vision impairment, one or more of the following may help restore vision:eyeglassescontact lensessurgerymedicationIf 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 Brailleuse a guide dogorganize your home so you can easily find things and stay safefold money in distinct ways to distinguish bill amountsYou can also consider getting some adaptive products, like a specialized smartphone, color identifier, and accessible cookware. There’s even adaptive sporting equipment, like sensory soccer balls. What’s the long-term outlook?A person’s long-term outlook for restoring vision and slowing vision loss is better when treatment is preventive and sought immediately. Surgery can effectively treat cataracts. They don’t necessarily result in blindness. Early diagnosis and treatment are also important in cases of glaucoma and macular degeneration to help slow down or stop vision loss. How can blindness be prevented?To detect eye diseases and help prevent vision loss, get regular eye examinations. If you receive a diagnosis of certain eye conditions, such as glaucoma, treatment with medication can help prevent blindness.To help prevent vision loss, the American Optometric Association recommends you have your child’s eyes examined: at 6 months of ageat 3 years of ageevery year between 6 and 17 years old If you notice symptoms of vision loss between routine visits, make an appointment with their eye doctor immediately. Last medically reviewed on September 4, 2019How we reviewed this article:SourcesHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.Blindness. (n.d.).https://nei.nih.gov/eyedata/blindMayo Clinic Staff. (2018). Cataracts.https://www.mayoclinic.org/diseases-conditions/cataracts/symptoms-causes/syc-20353790Mayo Clinic Staff. (2018). Glaucoma.https://www.mayoclinic.org/diseases-conditions/glaucoma/symptoms-causes/syc-20372839Recommended eye examination frequency forpediatric patients and adults. (n.d.).https://www.aoa.org/patients-and-public/caring-for-your-vision/comprehensive-eye-and-vision-examination/recommended-examination-frequency-for-pediatric-patients-and-adultsYour baby’s eyes. (n.d.).https://chicago.medicine.uic.edu/departments/academic-departments/ophthalmology-visual-sciences/our-department/media-center/eye-facts/baby-your-babys-eyesShare this articleMedically reviewed by Ann Marie Griff, O.D. — By Chitra Badii — Updated on September 5, 2019Read this nextFace Blindness (Prosopagnosia)Medically reviewed by Timothy J. Legg, PhD, PsyDREAD MOREEye Stroke: Symptoms, Causes, and MoreREAD MORETemporary Blindness in One Eye: What to KnowMedically reviewed by Ann Marie Griff, O.D.Sudden blindness (total or near-total vision loss) in one or both eyes is a medical emergency. In many cases, prompt diagnosis and treatment can…READ MOREFarsightednessMedically reviewed by Judith Marcin, M.D.READ MORECan Stress Cause Vision Problems or Blindness?Medically reviewed by Leela Raju, MDStress and anxiety can impair many aspects of your health, including your vision. It can cause symptoms like blurriness or light sensitivity.READ MOREChange Blindness Vs. Inattentional Blindness: Now You See It, Now You Don’tMedically reviewed by Leela Raju, MDThe difference in change blindness vs. inattentional blindness is subtle, but both involve not seeing things that are in your visual field. READ MOREWhat Is Change Blindness, and Why Does It Happen?Medically reviewed by Leela Raju, MDChange blindness is a visual phenomenon that happens when the thing you’re looking at undergoes some type of change and you don’t notice.READ MOREWhy Is Color Blindness More Common in Men?Medically reviewed by Leela Raju, MDColor blindness can be inherited or acquired. When it's inherited, it's usually passed through the X chromosome, making this condition more common in…READ MOREDoes Retinoblastoma Cause Blindness?Medically reviewed by Leela Raju, MDRetinoblastoma is a type of eye cancer that usually affects children. Untreated, it can cause blindness. Treatment may help save a child’s vision and…READ MOREHow Do Brain Tumors Affect Your Eyesight and Cause Blindness?Medically reviewed by Seunggu Han, M.D.The location or type of a brain tumor may help predict whether it will affect your vision or not. Prompt treatment may help restore or stop vision…READ MOREAbout UsContact UsPrivacy PolicyPrivacy SettingsAdvertising PolicyHealth TopicsMedical AffairsContent IntegrityNewsletters© 2024 Healthline Media LLC. All rights reserved. Our website services, content, and products are for informational purposes only. Healthline Media does not provide medical advice, diagnosis, or treatment. See additional information. See additional information.© 2024 Healthline Media LLC. All rights reserved. Our website services, content, and products are for informational purposes only. Healthline Media does not provide medical advice, diagnosis, or treatment. See additional information. 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Blindness (Vision Impairment): Types, Causes and Treatment

dness (Vision Impairment): Types, Causes and Treatment800.223.2273100 Years of Cleveland ClinicMyChartNeed Help?GivingCareersSearchClevelandClinic.orgFind A DoctorLocations & DirectionsPatients & VisitorsHealth LibraryInstitutes & DepartmentsAppointmentsHome/Health Library/Diseases & Conditions/BlindnessAdvertisementAdvertisementAdvertisementBlindnessBlindness can result from infections, accidents, genetic conditions and other diseases. Types of blindness can range from no vision at all to seeing shapes. Some types can be prevented or cured, but other types can’t be treated.ContentsArrow DownOverviewSymptoms and CausesDiagnosis and TestsManagement and TreatmentPreventionOutlook / PrognosisLiving WithContentsArrow DownOverviewSymptoms and CausesDiagnosis and TestsManagement and TreatmentPreventionOutlook / PrognosisLiving WithOverviewWhat is blindness?Blindness is the inability to see or a lack of vision. In the most severe cases, there’s an inability to see even light. It also means that you can’t correct your vision with eyeglasses, contact lenses, eye drops or other medical therapy, or surgery. Sudden vision loss is an emergency. It’s important to seek immediate medical help.Types of blindnessPartial blindness: You still have some vision. People often call this "low vision."Complete blindness: You can't see or detect light. This condition is very rare.Congenital blindness: This refers to poor vision that you are born with. The causes include inherited eye and retinal conditions and non-inherited birth defects.Legal blindness: This is when the central vision is 20/200 in your best-seeing eye even when corrected with glass or contact lenses. Having 20/200 vision means that you have to be 10x closer or an object has to be 10x larger in order to see compared to a person with 20/20 vision. In addition, you can be legally blind if your field of vision or peripheral vision is severely reduced (less than 20 degrees).Nutritional blindness: This term describes vision loss from vitamin A deficiency. If the vitamin A deficiency continues, damage to the front surface of the eye (xerophthalmia) This type of blindness can also make it more difficult to see at night or in dim light due to retinal cells not functioning as well.You might wonder about color blindness, which is not blindness in the traditional sense. Another name for this issue is color deficiency. You perceive colors in a different way. You can inherit this condition or acquire it because of disease or damage that occurs in your retina or optic nerve. If you can only see black, white or shades of gray, you have achromatopsia.You may also hear about preventable blindness or avoidable blindness. These terms refer to blindness that happens to people that have a diseases that is treatable but they never receive care. This often happens because of a lack of access to eye care or healthcare. For instance, people who never receive care for diabetes may develop diabetes-related retinopathy. People who don’t receive care for hypertension may develop hypertensive retinopathy.How common is blindness?Blindness is common throughout the world and in the U.S. It can happen to anyone.In the U.S., about 1 million people are blind. Experts expect this number to double by 2050. There are many more people with low vision. Around the world, an estimated 43 million people are living with blindness.AdvertisementCleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. PolicySymptoms and CausesWhat are the symptoms of blindness?With complete blindness there is a lack of vision and the inability of the eye to detect light.Symptoms that you may have while vision loss develops include:Blurry vision.Eye pain.Floaters and flashers.Sensitivity to light (photophobia).Sudden loss of vision, or the sudden appearance of black spots in your vision.What causes blindness?There are many causes of blindness, including injuries, infections and medical conditions.Eye injuries and blindnessEye injuries, or ocular trauma, can happen in many ways. It usually affects only one eye. Damage can result from:Chemical burns.Exposure to toxinsFights.Fireworks.Industrial accidents, including falls.Motor vehicle crashes.Sports.Infections and blindnessMany infectious diseases can lead to vision loss and sometimes blindness. These include:Trachoma. This is the leading cause of preventable blindness in the world.Cytomegalovirus.Endophthalmitis.Histoplasmosis.Keratitis, including acanthamoeba keratitis.Rubella.Shingles.Syphilis.Toxoplasmosis.Uveitis.Non-infectious diseases and blindnessMany non-infectious diseases can cause blindness, but some in only the most severe stages of the disease. These include:Retinitis pigmentosa. This term refers to a group of conditions that affect your retina, the part of your eye that has special cells that react to light. As the condition progresses, the retinal cells break down. This leads first to problems seeing at night and then subsequent loss of your peripheral vision.Age-related macular degeneration. This condition affects the macula, the part of your retina that controls central vision. When substantial central vision loss occurs, tasks like reading or recognizing people’s faces become very difficult, but your peripheral vision often remains intact.Retinopathy of prematurity. This retinal condition happens to some premature babies. Blood vessels grow into parts of their eye where they don’t belong. Scar tissue forms and can damage their retina, leading to significant vision loss and blindness.Cataracts. Cataracts cause vision loss by clouding the lenses of your eyes, leading a blurring of the vision and loss of contrast. Without access to surgical care, advanced cataracts can lead to blindness.Diabetes-related retinopathy. This condition may happen when you have diabetes and the blood vessels in the eye are damaged. The vision loss may be mild at first, but with progression or lack of treatment, blindness can occur.Glaucoma. With this condition, you have optic nerve damage. The vision loss often starts in the periphery but can lead to blindness in advanced stages of the disease.Leber hereditary optic neuropathy. This term refers to an inherited type of gradual vision loss. For unknown reasons, it affects males more than females.Anophthalmia. This disease happens when you’re born without one or both eyes.Microphthalmos. This disease happens when you’re born with very small eyes. Sometimes these smaller eyes don’t work as well as they should, or at all.Stroke. You can lose your eyesight from a stroke that occurs in an area of the brain that is involved in seeing, like the occipital lobe or along the visual tract. The stroke reduces or blocks blood flow to your brain.Cancer. Cancers, like retinoblastoma or orbital tumors, can cause eyes to become blind.Nutritional deficiencies. A poor diet can cause vision loss. Vitamin A deficiency is one cause, but you also need B vitamins and other minerals and vitamins for healthy vision.AdvertisementDiagnosis and TestsHow is blindness diagnosed?A provider will test each eye for sight, giving you a thorough eye exam. It’s possible for blindness to affect only one eye.Tests may include:The Snellen test: You’re probably familiar with this test. A provider asks you to read lines of letters that get smaller as they go down the page. This test of visual acuity measures what you can see in front of you (central vision).Visual field testing: The visual field means more than central vision. It’s what you can see to either side or above and below without moving your eye.Management and TreatmentHow is blindness treated?The type of treatment available depends on your condition. Providers can treat some forms of blindness with medications or glasses but can’t treat other types, such as the ones where your eyes are missing or completely damaged. In these cases, your provider may recommend visual rehabilitation. The goal of vision rehabilitation is to enhance visual functioning so you can meet your visual goals and improve your quality of life. Often, this happens through low-vision training, therapy and using low-vision devices.Treatment for various forms of blindnessTreatment exists for some forms of blindness, depending on the cause and how extensive the eye damage is.Medication: Anti-infective drugs treat some forms of blindness caused by infections.Cataract surgery: Surgery can treat cataracts successfully in most cases.Corneal transplant: A provider may be able to replace your scarred cornea.Retinal surgery: A provider may be able to repair damaged retinal tissue with surgery and/or a laser.Vitamin supplements: You may be able to reverse the vision loss of xerophthalmia by taking vitamin A. You may need vitamin B or vitamin D supplements to treat vision loss caused by a poor diet.Care at Cleveland ClinicEye CareFind a Doctor and SpecialistsMake an AppointmentAdvertisementPreventionHow can I reduce my risk of developing blindness?You can’t prevent some types of blindness. But blindness is preventable in many cases.Some governments and societies are working to stop blindness caused by preventable diseases, like trachoma. They’re making medicines more available in large areas of the world.On a personal level, there are things you can do to reduce your risk of partial or total blindness. These include:Have regularly scheduled eye exams. Follow the advice of healthcare providers on how often you should go for exams. Always contact an eye care provider when you have a change in vision or something wrong with your eyes. Wear your prescription glasses and contact lenses when necessary.Keep blood sugar levels stable if you’re a person with diabetes and manage your blood pressure if you have high blood pressure.Wear protective gear when you’re working, riding a motorcycle or participating in contact sports. Don’t forget to wear sunglasses.Eat foods that make up a healthy, well-rounded diet.Get enough exercise. Ask your provider about an exercise plan that’s healthy for you.Achieve a healthy weight for you.Know about health issues in your family.Quit smoking, or never start.Avoid infections in your eye by always washing your hands when you put your contacts in and following instructions about how often to change them.Outlook / PrognosisWhat can I expect if I have blindness?If you’re completely or partially blind, there are options. It may help to learn as much as you can about your condition.Living with blindness affects your life and the lives of your family and friends. It affects your mobility, your ability to care for yourself or others, your employment – it even affects how you relax and have fun. Some of these issues may be even more pressing for older adults.Ask your ophthalmologist about ways of coping with low or no vision or recommendations for services that can help you. These services can include:Education.Emotional health.Skills training.Technology training.Recreational options.Living WithWhen should I see a healthcare provider about vision issues?Get immediate medical help if you:Lose vision suddenly.Have pain in your eye.Have some type of accident that affects your vision.Have flashes or new floaters in your vision.What questions should I ask my provider?You probably have many questions for your provider. They may include:Can you treat this type of blindness?Am I eligible to participate in clinical trials?If you can’t treat this type of blindness, what kinds of services will I need?Can you recommend a support group?A note from Cleveland ClinicHearing a diagnosis of blindness may bring on many emotions because of the inevitable impact on your life. It’s important and practical to get whatever support you need. Members of your healthcare team are there to answer questions and help to provide tools to make sure you have the best quality of life.Medically ReviewedLast reviewed by a Cleveland Clinic medical professional on 11/14/2022.Learn more about our editorial process.ReferencesAdvertisementCleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. 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Blindness and vision impairment

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Blindness and vision impairment

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Blindness and vision impairment

10 August 2023

Key facts

Globally, at least 2.2 billion people have a near or distance vision impairment. In at least 1 billion of these, vision impairment could have been prevented or is yet to be addressed.

The leading causes of vision impairment and blindness at a global level are refractive errors and cataracts.

It is estimated that globally only 36% of people with a distance vision impairment due to refractive error and only 17% of people with vision impairment due to cataract have received access to an appropriate intervention.

Vision impairment poses an enormous global financial burden, with the annual global cost of productivity estimated to be US$ 411 billion.

Vision loss can affect people of all ages; however, most people with vision impairment and blindness are over the age of 50 years.

OverviewVision, the most dominant of our senses, plays a critical role in every facet and stage of our lives. We take vision for granted, but without vision, we struggle to learn, to walk, to read, to participate in school and to work. Vision impairment occurs when an eye condition affects the visual system and its vision functions. Everyone, if they live long enough, will experience at least one eye condition in their lifetime that will require appropriate care.Vision impairment has serious consequences for the individual across the life course. Many of these consequences can be mitigated by timely access to quality eye care. Eye conditions that can cause vision impairment and blindness – such as cataract or refractive error – are, for good reasons, the main focus of eye care strategies; nevertheless, the importance of eye conditions that do not typically cause vision impairment – such as dry eye or conjunctivitis – must not be overlooked. These conditions are frequently among the leading reasons for presentation to eye care services.CausesGlobally, the leading causes of vision impairment and blindness are:refractive errors cataractdiabetic retinopathyglaucomaage-related macular degeneration.There is substantial variation in the causes of vision impairment between and within countries according to the availability of eye care services, their affordability, and the education of the population. For example, the proportion of vision impairment attributable to unoperated cataract is higher in low- and middle-income countries. In high income countries, diseases such as glaucoma and age-related macular degeneration are more common.Among children, congenital cataract is a leading cause of vision impairment in low-income countries, whereas in middle-income countries it is more likely to be retinopathy of prematurity.Uncorrected refractive error remains a leading cause of vision impairment in all countries amongst children and adult populations.PrevalenceGlobally, at least 2.2 billion people have a near or distance vision impairment. In at least 1 billion – or almost half – of these cases, vision impairment could have been prevented or has yet to be addressed.Among this 1 billion people, the main conditions causing distance vision impairment or blindness are cataract (94 million), refractive error (88.4 million), age-related macular degeneration (8 million), glaucoma (7.7 million), diabetic retinopathy (3.9 million) (1). The main condition causing near vision impairment is presbyopia (826 million) (2).In terms of regional differences, the prevalence of distance vision impairment in low- and middle-income regions is estimated to be 4 times higher than in high-income regions (1). With regards to near vision, rates of unaddressed near vision impairment are estimated to be greater than 80% in western, eastern and central sub-Saharan Africa, while comparative rates in high-income regions of North America, Australasia, western Europe, and of Asia-Pacific are reported to be lower than 10% (2).Population growth and ageing are expected to increase the risk that more people acquire vision impairment.Impact of vision impairmentPersonal impactYoung children with early onset irreversible severe vision impairment can experience delayed motor, language, emotional, social and cognitive development, with lifelong consequences. School-age children with vision impairment can also experience lower levels of educational achievement.Vision impairment severely impacts quality of life among adult populations. Adults with vision impairment can experience lower rates of employment and higher rates of depression and anxiety.In the case of older adults, vision impairment can contribute to social isolation, difficulty walking, a higher risk of falls and fractures, and a greater likelihood of early entry into nursing or care homes.Economic impactVision impairment poses an enormous global financial burden with an estimate annual global productivity loss of about US$ 411 billion purchasing power parity (3). This figure far outweighs the estimated cost gap of addressing the unmet need of vision impairment (estimated at about US$ 25 billion).Strategies to address eye conditions to avoid vision impairmentThere are effective interventions covering promotion, prevention, treatment and rehabilitation which address the needs associated with eye conditions and vision impairment. While many vision loss cases can be prevented (such as those due to infections, trauma, unsafe traditional medicines, perinatal diseases, nutrition-related diseases, unsafe use or self-administration of topical treatment), this is not possible for all. For many eye conditions, e.g. diabetic retinopathy, early detection and timely treatment are crucial to avoid irreversible vision loss. Spectacle correction for refractive error and surgery for cataract are among the most cost-effective of all health-care interventions. Yet, globally only 36% of people with a distance vision impairment due to refractive error have received access to an appropriate pair of spectacles and only 17% of people with vision impairment or blindness due to cataract have received access to quality surgery.Treatment is also available for many eye conditions that do not typically cause vision impairment, such as dry eye, conjunctivitis and blepharitis, but generate discomfort and pain. Treatment of these conditions is directed at alleviating the symptoms and preventing the evolution towards more severe stages of those diseases.Vision rehabilitation is very effective in improving functioning for people with an irreversible vision loss that can be caused by eye conditions such as diabetic retinopathy, glaucoma, consequences of trauma, and age-related macular degeneration.WHO responseWHO’s work is guided by the recommendations of the WHO World report on vision (2019) and the resolution on "integrated, people-centred eye care, including preventable blindness and vision impairment" adopted at the Seventy-third World Health Assembly in 2020. The key proposal is to make integrated people-centred eye care (IPEC) the care model of choice and to ensure its widespread implementation. It is expected that by shaping the global agenda on vision and eye care, the report and resolution will assist Member States and their partners in their efforts to reduce the burden of eye conditions and vision.Some of WHO’s key areas of work and activities in the prevention of blindness include:Working with Member States and other partners in the field to monitor the global targets for 2030 on integrated people-centred eye care:Developing reports of the effective coverage of eye care indicators to monitor progress towards the 2030 global targets.Developing resources and technical tools to support the integration of eye care into health information systems.Observing and promoting World Sight Day as an annual advocacy event.Supporting the integration of eye care in health systems through the implementation of a series of technical tools:The Eye care in health systems: Guide for action.The Package of eye care interventions (PECI).The Eye care competency framework (ECCF).The development and implementation tools to support countries to assess the provision of eye care services such as:The Eye care situation analysis toolThe Tool for the assessment of diabetic retinopathy and diabetes management services.The Tool for the assessment of glaucoma services.The Tool for the assessment of refractive services.The Tool for the assessment of rehabilitation services and systems.The development of materials and resources to raise awareness on eye care:The MyopiaEd: a mobile health toolkit for myopia to increase health literacy.A population-facing app for near and distance visual acuity testing.Graphics promoting healthy eye habits. References1. GBD 2019 Blindness and Vision Impairment Collaborators; Vision Loss Expert Group of the Global Burden of Disease Study. Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study. Lancet Glob Health. 2021 Feb;9(2):e144-e160. doi: 10.1016/S2214-109X(20)30489-7.2. Fricke, TR, Tahhan N, Resnikoff S, Papas E, Burnett A, Suit MH, Naduvilath T, Naidoo K, Global Prevalence of Presbyopia and Vision Impairment from Uncorrected Presbyopia: Systematic Review, Meta-analysis, and Modelling, Ophthalmology. 2018 May 9.3. Burton MJ, Ramke J, Marques AP, Bourne RR, Congdon N, Jones I, et al. The Lancet Global Health commission on Global Eye Health: vision beyond 2020. Lancet Glob Health. 2021; 9(4):e489–e551.

Health topic pageWHO’s work on eye care, vision impairment and blindness (who.int)Related linksReport of the 2030 targets on effective coverage of eye care (who.int) Eye care in health systems: guide for action (who.int) World report on vision (who.int)

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eyesight health center/eyesight a-z list/blindness article

Blindness

Medical Author:

Andrew A. Dahl, MD, FACS

Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

Medically Reviewed on 5/4/2023

Introduction

What is blindness?

Types

What are the three types of blindness?

Causes

What are the causes of blindness?

Risk Factors

What are risk factors for blindness?

Signs & Symptoms

What are signs and symptoms of blindness?

Diagnosis

How do healthcare professionals diagnose blindness?

Treatment

What is the treatment for blindness?

Prognosis

What is the prognosis for blindness?

Prevention

How can you prevent going blind?

What is blindness?

Color blindness is the inability to perceive differences in various shades of colors, particularly green and red, that others can distinguish.

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 impairments.

Blindness is frequently used today to describe a severe visual decline in one or both eyes with the 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 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 three types of blindness?

There are three main types of blindness, which include the following:

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 not true blindness.

Night blindness is 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 a loss of vision after exposure of the eyes to large amounts of ultraviolet light. Snow blindness is usually temporary and is due to the swelling of cells on the corneal surface. Even in the most severe 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.

QUESTION

The colored part of the eye that helps regulate the amount of light that enters is called the:

See Answer

What are the causes of blindness?

The many causes of blindness differ according to the socio-economic condition of the nation being studied. In developed nations, the leading causes of blindness include:

Ocular complications of diabetes

Macular degeneration

Glaucoma

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)

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 include:

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

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 for blindness 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

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 the years, also can have more difficulty adjusting to their visual loss.

Associated symptoms of blindness may be present or absent, depending on the underlying cause of the condition, and may include:

Discomfort in the eyes

Awareness of the eyes

Foreign body sensation

Pain in the eyes or discharge from the eyes

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 an 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 cataracts, 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.

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What specialists diagnose and treat blindness?

Ophthalmology is the specialty of medicine that deals with the diagnosis and medical and surgical treatment of eye disease. Therefore, ophthalmologists are specialists who have the knowledge and tools to diagnose the cause of blindness and to provide treatment, if possible.How do healthcare 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 blindness can help diagnose the cause of blindness. Poor vision that is sudden in onset differs in potential causes from 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 is the treatment 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 can access surgical care for their condition.

How can you prevent going blind?

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 the 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 how they perform their everyday tasks. Organizations, such as the Braille Institute, offer helpful resources and support for people with blindness and 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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Medically Reviewed on 5/4/2023

References

American Academy of Ophthalmology. "Eye Health Statistics at a Glance." .

Switzerland. World Health Organization. "Visual Impairment and Blindness." Oct. 2017. .

Complete List

What Are the 7 Causes of Blindness?

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A Quiz for TeensAre You a Workaholic?How Well Do You Sleep?Tools & ResourcesHealth NewsFind a DietFind Healthy SnacksDrugs A-ZHealth A-ZConnectFind Your Bezzy CommunityBreast CancerInflammatory Bowel DiseasePsoriatic ArthritisMigraineMultiple SclerosisPsoriasisFollow us on social mediaHealthlineHealth ConditionsDiscoverPlanConnectSubscribe7 Common Causes of BlindnessMedically reviewed by Katherine E. Duncan, MD — By Jennifer M. Edwards on September 25, 2023Mascular degenerationGlaucomaCataractsDiabetesRetinitis pigmentosaAmblyopiaStrabismusOther causesPreventionFAQTakeawayBlindness is usually due to age-related conditions such as macular degeneration, glaucoma, or cataracts. But other rare conditions can also cause blindness in people of all ages.More than 4 million adults in the United States above the age of 40 years had low vision or were legally blind in 2022. Experts expect that number to double by 2050 as the population ages.While vision loss is usually age-related, other factors can also play a role. Read on to learn about seven of the most common causes of blindness, their risk factors, and how to reduce your risk.How do I know if I’m going blind?Signs of vision loss and blindness can be subtle and increase over time or can appear suddenly. Contact an eye doctor right away if you notice any of the following symptoms:seeing flashes of lightseeing floaters or specksseeing haloes around light sourcesdecreased visionwatery eyes or eye drainingeye rednessdouble visionlines look wavy or distortedempty areas in the center of your field of visionoften seeing changes in your vision qualitylosing peripheral visionintense eye painWas this helpful?Macular degenerationIf you’re older than 60 years, it helps to be aware of age-related macular degeneration (AMD). It’s the most common cause of vision loss in people of this age group. While not painful, it can slowly damage your central vision.AMD occurs when cells in the center of your retina (macula) get damaged over time. AMD has two types: wet and dry. Dry AMD is more common but less severe.An early sign of wet AMD is straight lines appearing crooked. With dry AMD, you may first experience blurred or distorted central vision.Risk factors for AMD include smoking or having a family history of the disease. White people may also be at a higher risk than other races.GlaucomaGlaucoma is a group of diseases that can damage the optic nerve in the back of your eye. About half of all people with glaucoma don’t know they have it because it can progress very slowly. It first damages your side (peripheral) vision and can eventually cause blindness.Researchers aren’t sure what causes glaucoma. It may be related to high eye pressure, but even people with regular eye pressure can develop it. Regular eye exams every 1–2 years can help doctors detect it early.Risk factors for glaucoma include:having a family history of glaucomabeing older than 60 years and Latinobeing older than 40 years and BlackCataractsA cataract is the clouding of the lenses because of the proteins in one or both of your eyes. These proteins form a dense area, making it hard for your lens to send clear images to other parts of your eye.Cataracts are a common, vision threatening eye conditions. The National Eye Institute estimates that by the age of 80 years, half of all adults in the United States will have cataract or cataract surgery in one or both eyes.Risk factors for cataracts include:agingsmoking (if you smoke)alcohol (if you drink)prolonged exposure to sunlightdiabetesDiabetic retinopathyPeople with diabetes are at risk of developing diabetic retinopathy, including those with type 1 and type 2 or who are pregnant (gestational diabetes).Frequent high blood sugar levels can damage blood vessels all over your body. It includes the tiny vessels in your retina, the area in the back of your eye that’s sensitive to light. The blood vessels can leak or grow unusually, causing vision loss and eventually blindness.Retinitis pigmentosaRetinitis pigmentosa (RP) is a rare group of inherited eye diseases. Genetic mutations that affect your retina can cause its cells to break down slowly.While RP typically gets passed from parent to child at birth, injuries, infections, and some medications can cause damage to the retina that resembles RP.Most people with RP eventually lose most of their sight.Risk factors for RP include a family history of the condition or having other genetic disorders like Usher syndrome.AmblyopiaMore commonly known as lazy eye, amblyopia typically affects just one eye. It usually starts in childhood, when your brain has trouble interpreting information from one of your eyes. Over time, the eye with better sight becomes stronger, while the eye affected by amblyopia becomes weaker.Many parents don’t know their children have the condition until a doctor diagnoses it.Risk factors for amblyopia include:family history of amblyopia, cataracts, or other eye conditionslow birth weight or premature birthdevelopmental disabilitiesStrabismusAmbylopia can often occur with strabismus or crossed eyes. Strabismus can also occur without amblyopia.Muscles surround your eyes, allowing them to move and focus. When they don’t team together well, the sight in both eyes doesn’t align correctly. That can cause your brain to rely on one eye more than the other. It takes treatment to help them see together.Researchers aren’t sure what causes strabismus, but risk factors include:family history of strabismushaving other eye conditionseye or brain injuryhaving Down syndrome or cerebral palsyOther causesLess common causes of blindness include:eye injuresbrain injurieseye surgery complicationsuncorrected refractive errorsgenetic disorderstrachoma, a chlamydia infection in your eyetumorsstrokeretinal detachmentsevere eye infectionsHow can I prevent blindness?Regular dilated eye exams are one of the best ways to prevent vision loss. They can also help you catch a condition early when the treatment can be more effective.You can also protect your vision by:managing your blood sugar levelseating a nutritious dietmaintaining a moderate weightquitting smoking (if you smoke) or never starting smoking Frequently asked questionsHere are some answers to common questions about the causes of blindness.What is the number one cause of blindness?Cataracts are the top cause of blindness worldwide and vision loss in the United States.What diseases cause blindness in young adults?The leading causes of vision loss in U.S. adults under age 40 are refractive errors, accidental eye injuries, and diabetes.What are the most common causes of blindness in children?Children make up to 3% of people with blindness worldwide. The most common causes of blindness in children in the United States are:retinopathy of prematuritynystagmuscataractsoptic nerve atrophyWhat degree of blindness is considered a disability?Legal blindness is when you cannot correct your vision above 20/200 in your better eye. That means you need to stand 20 feet away to see an object most people can see from 200 feet away. The Social Security Administration considers legal blindness a disability.You have low vision when it’s less than 20/40 in the better-seeing eye, even when you have corrected vision.TakeawayVision loss is becoming more common in the United States as the population ages. Age plays a significant role in the most common causes of vision loss, such as AMD, glaucoma, cataracts, and diabetic retinopathy.But vision loss can happen to anyone at any age. Checking your sight with regular eye exams, healthy habits, and a knowledge of possible risk factors is essential for prevention and early diagnosis. Last medically reviewed on September 25, 2023How we reviewed this article:SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.Adult vision: 41 to 60 years of age. (n.d.) https://www.aoa.org/healthy-eyes/eye-health-for-life/adult-vision-41-to-60-years-of-ageAmblyopia (lazy eye). (2022). https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/amblyopia-lazy-eyeCauses of childhood blindness in the United States. (2022). https://www.aao.org/eyenet/academy-live/detail/causes-of-childhood-blindness-in-united-statesCommon eye disorders and diseases. (2022). https://www.cdc.gov/visionhealth/basics/ced/index.htmlDiabetic retinopathy. (2022). https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/diabetic-retinopathyDietze J, et al. (2022). Glaucoma. https://www.ncbi.nlm.nih.gov/books/NBK538217/Eye disease facts for health professionals. (n.d.). https://www.nei.nih.gov/sites/default/files/2023-02/Eye_Disease_Facts_Health_Professionals.pdfFacts about vision loss. (2021). https://www.cdc.gov/ncbddd/childdevelopment/facts-about-vision-loss.htmlGlaucoma. (n.d.).https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/glaucomaIf you’re blind or have low vision — how we can help. (2023). https://www.ssa.gov/pubs/EN-05-10052.pdfIRIS registry. (2023). https://www.aao.org/iris-registryKeep an eye on your vision health. (2022). https://www.cdc.gov/visionhealth/resources/features/keep-eye-on-vision-health.htmlLegal blindness in America. (2023). https://www.aoa.org/news/clinical-eye-care/diseases-and-conditions/legal-blindness-in-americaLow vision. (2023). https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/low-visionMacula. (2016). https://www.aao.org/eye-health/anatomy/macula-6Refractive errors. (2022). https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/refractive-errorsRetinitis pigmentosa. (2022). https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/retinitis-pigmentosaStrabismus (crossed eyes). (n.d.). https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/strabismusTips to prevent vision loss. (2021). https://www.cdc.gov/visionhealth/risk/tips.htmUsher syndrome. (2021). https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/usher-syndromeVision loss and age. (2020).https://www.cdc.gov/visionhealth/risk/age.htmVisual impairment, blindness cases in U.S. expected to double by 2050. (2016).https://www.nei.nih.gov/about/news-and-events/news/visual-impairment-blindness-cases-us-expected-double-2050Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.Current VersionSep 25, 2023Written ByJennifer M. EdwardsEdited ByA. L. HeywoodMedically Reviewed ByKatherine E. Duncan, MDCopy Edited ByIrawati ElkunchwarShare this articleMedically reviewed by Katherine E. Duncan, MD — By Jennifer M. Edwards on September 25, 2023More in Your Sight, Your Health with Wet AMDWet Macular Degeneration: Treatments, Outlook, and MoreMacular DegenerationThe Most Effective Treatment for AMD: Anti-VEGF InjectionsLearning to Live with Wet AMDView allRead this nextWhat Is Metamorphopsia?Medically reviewed by Leela Raju, MDMetamorphopsia is a visual defect that causes linear objects, such as lines on a grid, to look curvy or rounded. It’s a symptom of retina problems.READ MORE7 Tips to Protect Your Vision and Avoid Macular DegenerationMacular degeneration is one of the leading causes of blindness in the United States. Here's how to keep your vision safe while enjoying the sun this…READ MOREThe Latest Breakthroughs in Wet Macular Degeneration TreatmentMedically reviewed by Ann Marie Griff, O.D.The current treatment for wet AMD is anti-VEGF medication, injected into the eye, but researchers are searching for easier, longer-lasting treatments…READ MOREGene-Therapy Treatment May Help People with Macular DegenerationREAD MOREAbout UsContact UsPrivacy PolicyPrivacy SettingsAdvertising PolicyHealth TopicsMedical AffairsContent IntegrityNewsletters© 2024 Healthline Media LLC. All rights reserved. Our website services, content, and products are for informational purposes only. Healthline Media does not provide medical advice, diagnosis, or treatment. See additional information. 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Blindness and vision loss

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Blindness and vision loss

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Blindness is a lack of vision. It may also refer to a loss of vision that cannot be corrected with glasses or contact lenses.Partial blindness means you have very limited vision.Complete blindness means you cannot see anything and do not see light. (Most people who use the term "blindness" mean complete blindness.) People with vision that is worse than 20/200, even with glasses or contact lenses, are considered legally blind in most states in the United States.Vision loss refers to the partial or complete loss of vision. This vision loss may happen suddenly or over a period of time.Some types of vision loss never lead to complete blindness.Causes

Vision loss has many causes. In the United States, the leading causes are:Accidents or injuries to the surface of the eye (chemical burns or sports injuries)DiabetesGlaucomaMacular degenerationThe type of partial vision loss may differ, depending on the cause:With cataracts, vision may be cloudy or fuzzy, and bright light may cause glareWith diabetes, vision may be blurred, there may be shadows or missing areas of vision, and difficulty seeing at nightWith glaucoma, there may be tunnel vision and missing areas of visionWith macular degeneration, the side vision is normal, but the central vision is slowly lost Other causes of vision loss include:Blocked blood vessels to the retinaComplications of premature birth (retrolental fibroplasia)Complications of eye surgeryLazy eyeOptic neuritisStrokeRetinitis pigmentosaTumors, such as retinoblastoma and optic nerve gliomaTotal blindness (no light perception) is often due to:Severe trauma or injuryComplete retinal detachmentEnd-stage glaucomaEnd stage diabetic retinopathySevere internal eye infection (endophthalmitis)Vascular occlusion (stroke in the eye) Home Care

When you have low vision, you may have trouble driving, reading, or doing small tasks such as sewing or making crafts. You can make changes in your home and routines that help you stay safe and independent. Many services will provide you with the training and support you need to live independently, including the use of low vision aids.When to Contact a Medical Professional

Sudden vision loss is always an emergency, even if you have not completely lost vision. You should never ignore vision loss, thinking it will get better.Contact an ophthalmologist or go to the emergency room immediately. Most serious forms of vision loss are painless, and the absence of pain in no way diminishes the urgent need to get medical care. Many forms of vision loss only give you a short amount of time to be successfully treated.What to Expect at Your Office Visit

Your health care provider will do a complete eye exam. The treatment will depend on the cause of the vision loss.For long-term vision loss, see a low-vision specialist, who can help you learn to care for yourself and live a full life.Alternative Names

Loss of vision; No light perception (NLP); Low vision; Vision loss and blindnessImages

Neurofibromatosis I - enlarged optic foramen

Low vision aids

References

Cioffi GA, Liebmann JM. Diseases of the visual system. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 395.Colenbrander A, Fletcher DC. Vision rehabilitation. In: Kellerman RD, Rakel DP, eds. Conn's Current Therapy 2022. Philadelphia, PA: Elsevier; 2022:530-535.Fricke TR, Tahhan N, Resnikoff S, et al, Global prevalence of presbyopia and vision impairment from uncorrected presbyopia: systematic review, meta-analysis, and modelling. Ophthalmology. 2018;125(10):1492-1499. PMID: 29753495 pubmed.ncbi.nlm.nih.gov/29753495/.Olitsky SE, Marsh JD. Disorders of vision. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 639.Raharja A, Whitefield L. Clinical approach to vision loss: a review for general physicians. Clin Med (Lond). 2022;22(2):95-99. PMID: 35304366 pubmed.ncbi.nlm.nih.gov/35304366/.Rein DB, Wittenborn JS, Zhang P, et al. The economic burden of vision loss and blindness in the United States. Ophthalmology. 2022;129(4):369-378. PMID: 34560128 pubmed.ncbi.nlm.nih.gov/34560128/.

Review Date 8/22/2022

Updated by: Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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Eye care, vision impairment and blindness

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Eye care, vision impairment and blindness

Overview

Eye conditions are remarkably common. Those who live long enough will experience at least one eye condition during their lifetime. Globally, at least 1 billion people have a near or distance vision impairment that could have been prevented or has yet to be addressed. In the absence of timely detection, reduced or absent eyesight can have long-term personal and economic effects. Vision impairment affects people of all ages, with the majority being over the age of 50. Young children with early onset severe vision impairment can experience lower levels of educational achievement, and in adults it often affects quality of life through lower productivity, decreased workforce participation and high rates of depression. Vision impairment and blindness impact the life of people everywhere. In low- and middle-income settings the burden of vision impairment can be even greater due to fewer opportunities to access the most essential eye care services.Cataracts and uncorrected refractive errors are estimated to be the leading causes of vision impairment; however, other causes for vision impairment cannot be ignored. Age-related macular degeneration, glaucoma, long standing systemic conditions like diabetes causing diabetic retinopathy, infectious diseases of the eye and trauma to the eye are all equally important causes for vision impairment that need to be addressed.

Prevention

Eye conditions that can be targeted effectively with preventive strategies include congenital and acquired eye conditions, myopia, ocular trauma, and ocular infections and inflammations. A good example of this is the practice of preventative lifestyle changes among children, including a combination of increased time spent outdoors and decreased near-work activities. This may delay the onset and slow the progression of myopia, which reduces the risk of high myopia and its complications later in life.Importantly, the prevention and management of systemic diseases, such as diabetes and hypertension, can also be effective in reducing the risk of ocular diseases. In addition, interventions to prevent vitamin A deficiency, measles and rubella, through vitamin A supplementation and immunization, are highly effective in reducing the risk of corneal opacities that can occur secondary to these conditions.Another example is the prevention of workplace ocular injuries through promoting the use of protective eye equipment (e.g., masks, protective goggles, visors etc.) during high-risk activities and industries (e.g., certain sports, agricultural activities, construction workers, welders etc.).

Treatment

Although effective interventions exist to address the two leading causes of vision impairment, namely optical correction for refractive errors and surgery for cataract, there remains a large unmet need for care. Spectacles are the most common intervention used worldwide to compensate for refractive error, as well as contact lenses and refractive surgeries. Spectacles and cataract surgery are both highly cost-effective interventions that can substantially improve a person’s quality of life. Treatment and care for many eye conditions, such as glaucoma, diabetic retinopathy, pterygium, amblyopia, strabismus and retinopathy of prematurity require long-term monitoring to control the progression of the condition. Treatment is also required for commonly presenting acute eye conditions that do not typically cause vision impairment but affect people’s lives with pain and discomfort (dry eye, conjunctivitis and blepharitis, etc.). To prevent further complications, the management of these eye conditions is often directed at treating the cause or alleviating the symptoms.Vision impairment that cannot be corrected or reversed requires rehabilitation measures, for which there are several available. For those who live with blindness, braille reading, counselling and home skills training, mobility training with white canes and digital assistive technologies can ensure free, independent and safe mobility.

Fact sheets Blindness and vision impairmentAssistive technologyDiabetesDisabilityTrachomaDatabases and tools WHOeyesRoutine health information systems – sensory functions toolkitInitiatives and groups SPECS 2030Global SPECS NetworkResolutions and decisions Integrated people-centred eye care, including preventable vision impairment and blindness (WHA73.4)Towards universal eye health: a global action plan 2014–2019 (WHA66.4)Prevention of avoidable blindness and visual impairment (WHA62.1)Prevention of avoidable blindness and visual impairment (WHA59.25)Elimination of avoidable blindness (WHA56.26)Global elimination of blinding trachoma (WHA51.11)Technical work Noncommunicable DiseasesSensory Functions, Disability and Rehabilitation

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Integrating eye care in health systems – guide for action

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Vision and eye screening implementation handbook

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The collection of routine data for eye and ear care from health facility reporting underpins health related decision-making in health policy, management...

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Vision and eye screening implementation handbook: information sheet

Vision and eye screening in primary health care plays a pivotal role in global eye care initiatives by facilitating early detection of various eye...

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WHOeyes is a free, population-facing, mobile software application (an app).WHOeyes is available for both iOS and Android mobile operating systems...

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Increasing eye care interventions to address vision impairment

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Blindness: Types, Causes, Risk Factor and More | MyVision.org

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Home / Eye Conditions & Diseases / Blindness

Blindness: Types, Causes, Risk Factor and More

Table of Contents

What is Blindness?

Types

Causes

Risk Factors

Signs & Symptoms

Treatment

Prevention

Frequently Asked Questions

References

Blindness is the inability to see with one’s eyes. Partial blindness refers to various levels of vision impairment, while total blindness refers to complete vision loss.

Blindness can be the result of an injury, an underlying disease or a congenital disability.

Treating eye diseases that lead to blindness can often prevent this outcome. Recognizing early symptoms of a developing eye problem is crucial to receiving treatment in an early enough stage to avoid any vision loss.

What Is Blindness?

Blindness is the inability to see, either partially or totally. Partial blindness is also sometimes referred to as vision impairment. Eye doctors diagnose it when:

A person’s best-corrected eyesight (the highest visual acuity they can reach using glasses, medication, or surgery) falls below a certain thresholdA person’s visual field (the area that can be seen when their eyes are fixed on a specific point) is significantly smaller than normal.

The World Health Organization categorizes visual impairment into three levels. They are:

Moderate visual impairment: someone with a visual acuity of 20/70 to 20/160Severe visual impairment: someone with visual acuity of 20/200 to 20/400 or visual field of 20 degrees or lessProfound visual impairment: someone with visual acuity of 20/500 to 20/1000 or visual field of 10 degrees or less

Types of Blindness

Aside from total and partial blindness, there are three additional types of blindness: color blindness, night blindness and snow blindness.

Color Blindness

Color blindness is the inability to distinguish different shades of colors or the inability to see some or all colors. Colorblind people cannot tell the difference between certain colors, especially green and red or blue and yellow. Some cannot see any color at all and view the world in only their shade of gray.

Night Blindness

Night blindness refers to difficulty of seeing at night or in poorly lit areas. Night blindness is not in itself a disorder but a symptom of retinal degradation. Many people with night blindness can see well during the day or in well-lit areas.

Snow Blindness

Snow blindness refers to a loss of vision because of intensive exposure to ultraviolet light. You can still see shapes and movements if you are snow blind, but your vision is permanently reduced. Wearing sunglasses while outdoors can prevent this condition.

Causes of Blindness

Aside from acute traumas and injuries to the face and eyes, several eye conditions can lead to advanced blindness. Among them are:

Age-related macular degenerationCataractsDiabetic retinopathyGlaucoma

Age-Related Macular Degeneration

Age-related macular degeneration is an eye condition that causes damage to the sharp and central vision. AMD damages the macula, the retina’s central part, resulting in the inability to see clearly and difficulty performing common tasks like driving and reading.

Someone with AMD has one of two types: wet AMD or dry AMD.

Wet AMD

Wet AMD occurs when abnormal blood vessels grow behind the macula and retina and cause fluid blockages within the eye. This type of AMD progresses quickly and requires emergency treatment.

Dry AMD

Dry AMD describes the thinning of the macula that happens gradually as you grow older. Dry AMD advances more slowly than wet AMD, eye-care professionals cannot treat it with either medication or surgery. However, lifestyle and diet changes can slow progression of this type of AMD.

Cataracts

Cataracts affect your eye’s lens and leading to cloudy vision, and they are the leading cause of blindness and the main cause of vision loss.

The condition can be congenital (existing from birth), or it can develop later in life because of a variety of factors. In an early stage, doctors treat it with prescription eyeglasses. Late-stage cataracts require surgery when they become advanced enough to cause blindness.

Cataract surgery removes your eye’s natural lens and replaces it with an artificial one. This removes the cataracts that are present and prevents more from growing.

Diabetic Retinopathy

Diabetic retinopathy is an eye condition common among people diagnosed with diabetes, and it affects both eyes. It occurs as a result of progressive damages to the retina’s blood vessels and the light-sensitive tissues found behind the eye.

The leading cause of blindness for Americans aged 20 and 74 years old, diabetic retinopathy progresses in four stages.

Stage 1: Mild non-proliferative retinopathy. Small areas of the blood vessels within your eyes start to swell. Stage 2: Moderate non-proliferative retinopathy. The swelling blocks some blood vessels in the retina.Stage 3: Severe non-proliferative retinopathy. Even more blockages form, and parts of the retina become undernourished. The body prepares to grow new blood vessels in those areas.Stage 4: Proliferative retinopathy. New blood vessels begin to grow along the retina and inside the vitreous fluid. These new vessels are weak and often leak or break, potentially leading to severe vision loss or blindness.

Glaucoma

Glaucoma refers to a collection of eye conditions that can destroy the eye’s optic nerve. There are two types of glaucoma: open-angle and closed-angle.

Open-angle glaucoma is chronic and progresses slowly. You may fail to notice any effects on your visions until it has advanced significantly. Closed-angle glaucoma can occur instantly and progress quickly. It can also be very painful.

Ophthalmologists can treat both types, and the earlier the treatment begins the more likely it is to prevent blindness.

Risk Factors

Some major risk factors for blindness include:

AgingThe existence of certain diseases like diabetes mellitus, cardiovascular disease and hypertensionPremature birthThe presence of some vision disorders like strabismus and amblyopiaFamily history of blindness, diabetes or other vision-related illnessesPoor nutritionFailure to wear protective glassesPoor prenatal care (e.g., maternal smoking)

Signs and Symptoms

If you have total blindness, you will not see anything regardless of lighting or location. If you have partial blindness, you may experience:

Poor vision in low-light areasCloudy visionDouble visionDecrease in visionInability to tell what shape objects are

Early Signs and Symptoms of Blindness

Blindness rarely happens suddenly. Some of the early signs and symptoms of this condition include:

Excessive light sensitivityEye painDifficulty focusingItchy eye.Red eyesAbnormal eye alignmentPupils changing color from black to white

These signs and symptoms are common to many different eye disorders, and not all of them lead to blindness. Do not panic if you have one or more of the symptoms listed above. Your eye doctor will tell you if there is cause for concern.

Treatment Advances for Blindness

There are many different treatments for eye conditions that cause blindness.

Refractive errors can be treated using prescription eyeglasses or contact lenses.Glaucoma can be treated using medications that lower eye pressure.Wet form macular degeneration can be treated with injections and medications.Cataracts can be treated with cataract surgery.Corneal scarring or swelling can be treated with a corneal transplant.

The U.S. Food and Drug Administration (FDA) also recently approved a gene therapy drug that treats certain forms of inherited vision loss.

Preventing Blindness

To help reduce your risk of blindness, you can:

Control your blood sugar levels. Diabetes mellitus is a leading cause of blindness. Consult your doctor to help you manage your blood sugar, blood pressure and cholesterol levels. Eat nutritious food. Research has shown that food items like salmon and tuna, rich in omega-3 fatty acids, are good for your eye health.Protect yourself from eye injuries. Putting on protective gear while working or playing sports helps prevent blindness due to injuries.Do not smoke. Research has shown that smoking can lead to blindness by increasing your risk of developing cataracts, optic nerve damage and age-related macular degeneration.Visit your eye doctor regularly. If you have any symptoms of early blindness, your eye doctor will notice them and deliver the appropriate treatment.

FAQs

What causes blindness?

The leading causes of blindness in the US are eye conditions like age-related macular degeneration, diabetic retinopathy, cataracts and glaucoma.

Uncorrected refractive errors account for a majority of blindness cases in developing countries. Other potential causes include strabismus, amblyopia, poor nutrition, smoking and eye injuries.

What are the types of blindness?

There are four primary types of blindness: color blindness, light blindness, snow blindness and total blindness. The differences among them are:

Color blindness is the inability to distinguish certain colors. Night blindness is the inability to see in low light environments. Snow blindness is the inability to see because of the effects of ultraviolet light. Total blindness refers to complete loss of vision.

References

Common Eye Disorders and Diseases. (June 2020). Centers for Disease Control and Prevention.

Blindness and Vision Impairment. (October 2021). World Health Organization.

Fast Facts about Vision Loss. (June 2020). Centers for Disease Control and Prevention.

Types of Color Blindness. (June 2019). National Eye Institute.

What is Night Blindness? (December 2020). Cleveland Clinic.

Effects of ultraviolet light on the eye: role of protective glasses. (December 1991). Environmental Health Perspectives.

Revision of visual impairment definitions in the International Statistical Classification of Diseases. (March 2006). BMC Medicine.

Diabetic Retinopathy. (May 2019). Handbook of Clinical Neurology.

Glaucoma and Eye Pressure. (September 2021). National Eye Institute.

Prevalence and risk factors for eye diseases, blindness, and low vision in Lhasa, Tibet. (April 2013). International Journal of Ophthalmology.

What Is Adult Strabismus? (November 2021). American Academy of Ophthalmology.

Amblyopia (Lazy Eye). (October 2020). Cleveland Clinic.

Ab externo implantation of the MicroShunt, a poly (styrene-block-isobutylene-block-styrene) surgical device for the treatment of primary open-angle glaucoma: a review. (November 2019). BioMed Central.

Cornea Transplant. (February 2018). Cleveland Clinic.

FDA approves novel gene therapy to treat patients with a rare form of inherited vision loss. (December 2018). The Federal Drug Administration Agency.

Prevention of blindness and priorities for the future. (July 2001). The World Health Organization Bulletin.

Tips to Prevent Vision Loss. (August 2021). Centers for Disease Control and Prevention.

Smoking and Eye Disease. (March 2022). American Academy of Ophthalmology.

Last Updated April 4, 2022

Note: This page should not serve as a substitute for professional medical advice from a doctor or specialist. Please review our about page for more information.

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Blindness: Symptoms, Causes, Risk Factors & More

Blindness (Vision Impairment): Types, Causes and Treatment

Blindness and vision impairment

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Blindness Types, Causes, Disability, Diagnosis & Symptoms

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