| Visual impairment | |
|---|---|
| Other names | Vision impairment, vision loss |
 | |
| A typicalSnellen chart that is frequently used forvisual acuity testing | |
| Specialty | Ophthalmology |
| Symptoms | Decreased ability tosee[1][2] |
| Complications | Non-24-hour sleep–wake disorder,falls in older adults[3][4] |
| Causes | Uncorrectedrefractive errors,cataracts,glaucoma[1] |
| Diagnostic method | Eye examination[2] |
| Treatment | Vision rehabilitation, changes in the environment, assistive devices (eyeglasses,white cane)[2] |
| Frequency | 940 million / 13% (2015)[5] |
Visual orvision impairment (VI orVIP) is the partial or total inability ofvisual perception. In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficulties with normal daily tasks, including reading and walking.[6] The termslow vision andblindness are often used for levels of impairment which are difficult or impossible to correct and significantly impact daily life.[7] In addition to the various permanent conditions, fleeting temporary vision impairment,amaurosis fugax, may occur, and may indicate serious medical problems.[8][9][10]
The most common causes of visual impairment globally are uncorrectedrefractive errors (43%),cataracts (33%), andglaucoma (2%).[1] Refractive errors includenear-sightedness,far-sightedness,presbyopia, andastigmatism.[1] Cataracts are the most common cause of blindness.[1] Other disorders that may cause visual problems includeage-related macular degeneration,diabetic retinopathy,corneal clouding,childhood blindness, and a number ofinfections.[11] Visual impairment can also be caused by problems in thebrain due tostroke,premature birth, or trauma, among others.[12] These cases are known ascortical visual impairment.[12] Screening for vision problems in children may improve future vision and educational achievement.[13] Screening adults without symptoms is of uncertain benefit.[14] Diagnosis is by aneye exam.[2]
TheWorld Health Organization (WHO) estimates that 80% of visual impairment is either preventable or curable with treatment.[1] This includes cataracts, the infectionsriver blindness andtrachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some cases of childhood blindness.[15] Many people with significant visual impairment benefit fromvision rehabilitation, changes in their environment, and assistive devices.[2]
As of 2015[update], there were 940 million people with some degree of vision loss.[5] 246 million had low vision and 39 million were blind.[1] The majority of people with poor vision are in thedeveloping world and are over the age of 50 years.[1] Rates of visual impairment have decreased since the 1990s.[1] Visual impairments have considerable economic costs both directly due to the cost of treatment and indirectly due to decreased ability to work.[16]
In 2010, the WHO definition for visual impairment was changed and now follows theICD-11. The previous definition which used "best corrected visual acuity" was changed to "presenting visual acuity". This change was made as newer studies showed that best-corrected vision overlooks a larger proportion of the population who has visual impairment due to uncorrected refractive errors, and/or lack of access to medical or surgical treatment.[17]
Distance vision impairment:
Near vision impairment:
Severely sight impaired
Sight impaired
Low vision
In the UK, the Certificate of Vision Impairment (CVI) is used to certify people as being severely sight impaired or sight impaired.[19] The accompanying guidance for clinical staff states: "The National Assistance Act 1948 states that a person can be certified as severely sight impaired if they are 'so blind as to be unable to perform any work for which eye sight is essential'". Certification is based on whether a person can do any work for which eyesight is essential, not just one particular job (such as their job before becoming blind).[20]
In practice, the definition depends on individuals'visual acuity and the extent to which theirfield of vision is restricted. TheDepartment of Health identifies three groups of people who may be classified as severely visually impaired.[20]
The Department of Health also state that a person is more likely to be classified as severely visually impaired if their eyesight has failed recently or if they are an older individual, both groups being perceived as less able to adapt to their vision loss.[20]
In the United States, any person with vision that cannot be corrected to better than 20/200 in the better eye, or who has 20degrees (diameter) or less of visual field remaining, is considered legally blind or eligible for disability classification and possible inclusion in certain government sponsored programs.
The termspartially sighted,low vision,legally blind andtotally blind are used by schools, colleges, and other educational institutions to describe students with visual impairments.[21] They are defined as follows:
In 1934, theAmerican Medical Association adopted the following definition of blindness:
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.[22]
TheUnited States Congress included this definition as part of the Aid to the Blind program in theSocial Security Act passed in 1935.[22][23] In 1972, the Aid to the Blind program and two others combined under Title XVI of the Social Security Act to form theSupplemental Security Income program[24] which states:
An individual shall be considered to be blind for purposes of this title if he has central visual acuity of 20/200 or less in the better eye with the use of a correcting lens. An eye which is accompanied by a limitation in the fields of vision such that the widest diameter of the visual field subtends an angle no greater than 20 degrees shall be considered for purposes of the first sentence of this subsection as having a central visual acuity of 20/200 or less. An individual shall also be considered to be blind for purposes of this title if he is blind as defined under a State plan approved under title X or XVI as in effect for October 1972 and received aid under such plan (on the basis of blindness) for December 1973, so long as he is continuously blind as so defined.[25]
Vision impairment for a few seconds, or minutes, may occur due to any of a variety of causes, some serious and requiring medical attention.
Visual impairments may take many forms and be of varying degrees. Visual acuity alone is not always a good predictor of an individual's function. Someone with relatively good acuity (e.g., 20/40) can have difficulty with daily functioning, while someone with worse acuity (e.g., 20/200) may function reasonably well if they have low visual demands.
Best-corrected visual acuity differs from presenting visual acuity; a person with a "normal" best corrected acuity can have "poor" presenting acuity (e.g. individual who has uncorrected refractive error). Thus, measuring an individual's general functioning depends on one's situational and contextual factors, as well as access to treatment.[26]
TheAmerican Medical Association has estimated that the loss of one eye equals 25% impairment of the visual system and 24% impairment of the whole person;[27][28] total loss of vision in both eyes is considered to be 100% visual impairment and 85% impairment of the whole person.[27]
Some people who fall into this category can use their considerable residual vision – their remaining sight – to complete daily tasks without relying on alternative methods. The role of a low vision specialist (optometrist or ophthalmologist) is to maximize the functional level of a patient's vision by optical or non-optical means. Primarily, this is by use of magnification in the form of telescopic systems for distance vision and optical or electronic magnification for near tasks.
People with significantly reduced acuity may benefit from training conducted by individuals trained in the provision of technical aids. Lowvision rehabilitation professionals, some of whom are connected to an agency for the blind, can provide advice on lighting and contrast to maximize remaining vision. These professionals also have access to non-visual aids, and can instruct patients in their uses.
Older adults with visual impairment are at an increased risk of physical inactivity,[29][30] slower gait speeds,[31][32][33] and fear of falls.[34]
Physical activity is a useful predictor of overall well-being, and routine physical activity reduces the risk of developing chronic diseases and disability.[35][36] Older adults with visual impairment (including glaucoma, age-related macular degeneration, and diabetic retinopathy) have decreased physical activity as measured with self-reports and accelerometers.[37][38] The USNational Health and Nutrition Examination Survey (NHANES) showed that people with corrected visual acuity of less than 20/40 spent significantly less time in moderate to vigorous physical activity.[39] Age-related macular degeneration is also associated with a 50% decrease in physical activity–however physical activity is protective against age-related macular degeneration progression.[40][41]
In terms of mobility, those with visual impairment have a slower gait speed than those without visual impairment; however, the rate of decline remains proportional with increasing age in both groups. Additionally, the visually impaired also have greater difficulty walking a quarter mile (400 m) and walking up stairs, as compared to those with normal vision.[42]
Older adults with vision loss are at an increased risk of memory loss, cognitive impairment, and cognitive decline.[43]
Studies demonstrate an association between older adults with visual impairment and a poor mental health;[44][45][46][47] discrimination was identified as one of the causes of this association.[48] Older adults with visual impairment have a 1.5-fold risk of reporting perceived discrimination and of these individuals, there was a 2-fold risk of loneliness and 4-fold risk of reporting a lower quality of life.[48] Among adults with visual impairment, the prevalence of moderate loneliness is 28.7% (18.2% in general population) and prevalence of severe loneliness is 19.7% (2.7% in general population).[44] The risk of depression and anxiety are also increased in the visually impaired; 32.2% report depressive symptoms (12.01% in general population), and 15.61% report anxiety symptoms (10.69% in general population).[46]
The subjects making the most use of rehabilitation instruments, who lived alone, and preserved their own mobility and occupation were the least depressed, with the lowest risk of suicide and the highest level of social integration.
Those with worsening sight and the prognosis of eventual blindness are at comparatively high risk of suicide and thus may be in need of supportive services. Many studies have demonstrated how rapid acceptance of the serious visual impairment has led to a better, more productive compliance with rehabilitation programs. Moreover, psychological distress has been reported to be at its highest when sight loss is not complete, but the prognosis is unfavorable. Therefore, early intervention is imperative for enabling successful psychological adjustment.[49]
Blindness can occur in combination with such conditions asintellectual disability,autism spectrum disorders,cerebral palsy,hearing impairments, andepilepsy.[50][51] Blindness in combination with hearing loss is known asdeafblindness.
It has been estimated that over half of completely blind people havenon-24-hour sleep–wake disorder, a condition in which a person'scircadian rhythm, normally slightly longer than 24 hours, is notentrained (synchronized) to the light–dark cycle.[52][53]
The most common causes of visual impairment globally in 2010 were:
The most common causes of blindness worldwide in 2010 were:
About 90% of people who are visually impaired live in thedeveloping world.[1] Age-related macular degeneration, glaucoma, and diabetic retinopathy are the leading causes of blindness in the developed world.[54]
Among working-age adults who are newly blind in England and Wales the most common causes in 2010 were:[55]
Cataracts are the greying or opacity of the crystalline lens, which can be caused in children by intrauterine infections, metabolic disorders, and genetically transmitted syndromes.[56] Cataracts are the leading cause of child and adult blindness that doubles in prevalence with every ten years after the age of 40.[57] Consequently, today cataracts are more common among adults than in children.[56] That is, people face higher chances of developing cataracts as they age. Nonetheless, cataracts tend to have a greater financial and emotional toll upon children as they must undergo expensive diagnosis, long term rehabilitation, and visual assistance.[58] Also, according to the Saudi Journal for Health Sciences, sometimes people experience irreversible amblyopia[56] after pediatric cataract surgery because the cataracts prevented the normal maturation of vision prior to operation.[59] Despite the great progress in treatment, cataracts remain a global problem in both economically developed and developing countries.[60] At present, with the variant outcomes as well as the unequal access to cataract surgery, the best way to reduce the risk of developing cataracts is to avoid smoking and extensive exposure to sun light (i.e. UV-B rays).[57]
Glaucoma is an eye disease often characterized by increased pressure within the eye or intraocular pressure (IOP).[61] Glaucoma causes visual field loss as well as severs the optic nerve.[62] Early diagnosis and treatment of glaucoma in patients is imperative because glaucoma is triggered by non-specific levels of IOP.[62] Also, another challenge in accurately diagnosing glaucoma is that the disease has four causes: 1) inflammatory ocular hypertension syndrome (IOHS); 2) severe uveitic angle closure; 3) corticosteroid-induced; and 4) a heterogonous mechanism associated with structural change and chronic inflammation.[61] In addition, oftenpediatric glaucoma differs greatly in cause and management from the glaucoma developed by adults.[63] Currently, the best sign of pediatric glaucoma is an IOP of 21 mm Hg or greater present within a child.[63] One of the most common causes of pediatric glaucoma is cataract removal surgery, which leads to an incidence rate of about 12.2% among infants and 58.7% among 10-year-olds.[63]
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Childhood blindness can be caused by conditions related to pregnancy, such ascongenital rubella syndrome andretinopathy of prematurity. Leprosy and onchocerciasis each blind approximately 1 million individuals in the developing world.
The number of individuals blind fromtrachoma has decreased in the past 10 years from 6 million to 1.3 million, putting it in seventh place on the list of causes of blindness worldwide.
Central corneal ulceration is also a significant cause of monocular blindness worldwide, accounting for an estimated 850,000 cases of corneal blindness every year in the Indian subcontinent alone. As a result, corneal scarring from all causes is now the fourth greatest cause of global blindness.[64]
Eye injuries, most often occurring in people under 30, are the leading cause of monocular blindness (vision loss in one eye) throughout theUnited States. Injuries and cataracts affect the eye itself, while abnormalities such asoptic nerve hypoplasia affect the nerve bundle that sends signals from the eye to the back of the brain, which can lead to decreased visual acuity.
Cortical blindness results from injuries to theoccipital lobe of thebrain that prevent the brain from correctly receiving or interpreting signals from theoptic nerve. Symptoms of cortical blindness vary greatly across individuals and may be more severe in periods of exhaustion or stress. It is common for people with cortical blindness to have poorer vision later in the day.
Blinding has been used as anact of vengeance and torture in some instances, to deprive a person of a major sense by which they can navigate or interact within the world, act fully independently, and be aware of events surrounding them. An example from the classical realm isOedipus, who gouges out his own eyes after realizing that he fulfilled the awful prophecy spoken of him. Having crushed the Bulgarians, the Byzantine EmperorBasil II blinded as many as 15,000 prisoners taken in the battle, before releasing them.[65] Contemporary examples include the addition of methods such asacid throwing as a form ofdisfigurement.
People withalbinism often have vision loss to the extent that many are legally blind, though few of them actually cannot see.Leber congenital amaurosis can cause total blindness or severe sight loss from birth or early childhood.Retinitis pigmentosa is characterized by decreased peripheral vision and trouble seeing at night.
Advances inmapping of thehuman genome have identified other genetic causes oflow vision or blindness. One such example isBardet–Biedl syndrome.
Rarely, blindness is caused by the intake of certain chemicals. A well-known example ismethanol, which is only mildly toxic and minimally intoxicating, and breaks down into the substancesformaldehyde andformic acid which in turn can cause blindness, an array of other health complications, and death.[66] When competing withethanol for metabolism, ethanol is metabolized first, and the onset of toxicity is delayed. Methanol is commonly found inmethylated spirits,denatured ethyl alcohol, to avoid paying taxes on selling ethanol intended for human consumption. Methylated spirits are sometimes used byalcoholics as adesperate and cheap substitute for regular ethanolalcoholic beverages.
It is important that people be examined by someone specializing in low vision care prior to other rehabilitation training to rule out potential medical or surgical correction for the problem and to establish a careful baseline refraction and prescription of both normal and low vision glasses and optical aids. Only a doctor is qualified to evaluate visual functioning of a compromised visual system effectively.[73] TheAmerican Medical Association provides an approach to evaluating visual loss as it affects an individual's ability to perform activities of daily living.[27]
Screening adults who have no symptoms is of uncertain benefit.[14]
The World Health Organization estimates that 80% of visual loss is either preventable or curable with treatment.[1] This includes cataracts, onchocerciasis, trachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some cases of childhood blindness.[15] The Center for Disease Control and Prevention estimates that half of blindness in the United States is preventable.[2]
Many people with serious visual impairments can travel independently, using a wide range of tools and techniques.Orientation and mobility specialists are professionals who are specifically trained to teach people with visual impairments how to travel safely, confidently, and independently in the home and the community. These professionals can also help blind people to practice travelling on specific routes which they may use often, such as the route from one's house to a convenience store. Becoming familiar with an environment or route can make it much easier for a blind person to navigate successfully.
Tools such as thewhite cane with a red tip – theinternational symbol of blindness – may also be used to improve mobility. A long cane is used to extend the user's range of touch sensation. It is usually swung in a low sweeping motion, across the intended path of travel, to detect obstacles. However, techniques for cane travel can vary depending on the user and/or the situation. Some visually impaired persons do not carry these kinds of canes, opting instead for the shorter, lighter identification (ID) cane. Still others require a support cane. The choice depends on the individual's vision, motivation, and other factors.
A small number of people employguide dogs to assist in mobility. These dogs are trained to navigate around various obstacles, and to indicate when it becomes necessary to go up or down a step. However, the helpfulness of guide dogs is limited by the inability of dogs to understand complex directions. The human half of the guide dog team does the directing, based upon skills acquired through previous mobility training. In this sense, the handler might be likened to an aircraft's navigator, who must know how to get from one place to another, and the dog to the pilot, who gets them there safely.
GPS devices can also be used as a mobility aid. Such software can assist blind people with orientation and navigation, but it is not a replacement for traditional mobility tools such as white canes and guide dogs.
Some blind people are skilled atecholocating silent objects simply by producing mouth clicks and listening to the returning echoes. It has been shown that blind echolocation experts use what is normally the "visual" part of their brain to process the echoes.[74][75]
Government actions are sometimes taken to make public places more accessible to blind people. Public transportation is freely available to blind people in many cities.Tactile paving andaudible traffic signals can make it easier and safer for visually impaired pedestrians to cross streets. In addition to making rules about who can and cannot use a cane, some governments mandate theright-of-way be given to users of white canes or guide dogs.
Most visually impaired people who are not totally blind read print, either of a regular size or enlarged by magnification devices. Many also readlarge-print, which is easier for them to read without such devices. A variety ofmagnifying glasses, some handheld, and some on desktops, can make reading easier for them.
Others readbraille (or the infrequently usedMoon type), or rely ontalking books and readers orreading machines, which convert printed text to speech orbraille. They use computers with special hardware such asscanners andrefreshable braille displays as well as software written specifically for the blind, such asoptical character recognition applications andscreen readers.
Some people access these materials through agencies for the blind, such as theNational Library Service for the Blind and Physically Handicapped in the United States, theNational Library for the Blind or theRNIB in the United Kingdom.
Closed-circuit televisions, equipment that enlarges and contrasts textual items, are a morehigh-tech alternative to traditional magnification devices.
There are also over 100radio reading services throughout the world that provide people with vision impairments with readings from periodicals over the radio. The International Association of Audio Information Services provides links to all of these organizations.
Access technology such asscreen readers,screen magnifiers andrefreshable braille displays enable the blind to use mainstream computer applications andmobile phones. The availability of assistive technology is increasing, accompanied by concerted efforts to ensure the accessibility of information technology to all potential users, including the blind. Later versions ofMicrosoft Windows include an Accessibility Wizard & Magnifier for those with partial vision, andMicrosoft Narrator, a simple screen reader.Linux distributions (aslive CDs) for the blind includeVinux andAdriane Knoppix, the latter developed in part byAdriane Knopper who has a visual impairment. macOS and iOS also come with a built-in screen reader calledVoiceOver, whileGoogle TalkBack is built in to most Android devices.
The movement towards greaterweb accessibility is opening a far wider number of websites toadaptive technology, making the web a more inviting place for visually impaired surfers.
Experimental approaches insensory substitution are beginning to provide access to arbitrary live views from acamera.
Modified visual output that includes large print and/or clear simple graphics can be of benefit to users with some residual vision.[76]
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Blind people may use talking equipment such asthermometers, watches, clocks,scales,calculators, andcompasses. They may also enlarge or mark dials on devices such as ovens and thermostats to make them usable. Other techniques used by blind people to assist them in daily activities include:
Most people, once they have been visually impaired for long enough, devise their own adaptive strategies in all areas of personal and professional management.
For the blind, there are books in braille, audio-books, and text-to-speech computer programs, machines ande-book readers. Low vision people can make use of these tools as well aslarge-print reading materials and e-book readers that provide largefont sizes.
Computers are important tools of integration for the visually impaired person. They allow, using standard or specific programs, screen magnification and conversion of text into sound or touch (braille line), and are useful for all levels of visual impairment.OCR scanners can, in conjunction with text-to-speech software, read the contents of books and documents aloud via computer. Vendors also build closed-circuit televisions that electronically magnify paper, and even change its contrast and color, for visually impaired users. For more information, consultassistive technology.
In adults with low vision there is no conclusive evidence supporting one form of reading aid over another.[78] In several studies stand-mounted devices allowed faster reading than hand-held or portable optical aids.[78] While electronic aids may allow faster reading for individuals with low vision, portability, ease of use, and affordability must be considered for people.[78]
Children with low vision sometimes have reading delays, but do benefit from phonics-based beginning reading instruction methods. Engaging phonics instruction is multisensory, highly motivating, and hands-on. Typically students are first taught the most frequent sounds of the alphabet letters, especially the so-called short vowel sounds, then taught to blend sounds together with three-letter consonant-vowel-consonant words such as cat, red, sit, hot, sun. Hands-on (or kinesthetically appealing) VERY enlarged print materials such as those found in "The Big Collection of Phonics Flipbooks" by Lynn Gordon (Scholastic, 2010) are helpful for teaching word families and blending skills to beginning readers with low vision. Beginning reading instructional materials should focus primarily on the lower-case letters, not the capital letters (even though they are larger) because reading text requires familiarity (mostly) with lower-case letters. Phonics-based beginning reading should also be supplemented with phonemic awareness lessons, writing opportunities, and many read-alouds (literature read to children daily) to stimulate motivation, vocabulary development, concept development, and comprehension skill development. Many children with low vision can be successfully included in regular education environments. Parents may need to be vigilant to ensure that the school provides the teacher and students with appropriate low vision resources, for example technology in the classroom, classroom aide time, modified educational materials, and consultation assistance with low vision experts.
TheWHO estimates that in 2012 there were 285 million visually impaired people in the world, of which 246 million had low vision and 39 million were blind.[1]
Of those who are blind 90% live in the developing world.[79] Worldwide for each blind person, an average of 3.4 people have low vision, with country and regional variation ranging from 2.4 to 5.5.[80]
By age: Visual impairment is unequally distributed across age groups. More than 82% of all people who are blind are 50 years of age and older, although they represent only 19% of the world's population. Due to the expected number of years lived in blindness (blind years), childhood blindness remains a significant problem, with an estimated 1.4 million blind children below age 15.
By gender: Available studies consistently indicate that in every region of the world, and at all ages, females have a significantly higher risk of being visually impaired than males.[81][82][83][84][85][86]
By geography: Visual impairment is not distributed uniformly throughout the world. More than 90% of the world's visually impaired live in developing countries.[80]
Since the estimates of the 1990s, new data based on the 2002 global population show a reduction in the number of people who are blind or visually impaired, and those who are blind from the effects of infectious diseases, but an increase in the number of people who are blind from conditions related to longer life spans.[80]
In 1987, it was estimated that 598,000 people in the United States met the legal definition of blindness.[87] Of this number, 58% were over the age of 65.[87] In 1994–1995, 1.3 million Americans reported legal blindness.[88]
To determine which people qualify for special assistance because of their visual disabilities, various governments have specific definitions for legal blindness.[89] InNorth America and most ofEurope, legal blindness is defined asvisual acuity (vision) of 20/200 (6/60) or less in the better eye with best correction possible. This means that a legally blind individual would have to stand 20 feet (6.1 m) from an object to see it – withcorrective lenses – with the same degree of clarity as a normally sighted person could from 200 feet (61 m). In many areas, people with average acuity who nonetheless have avisual field of less than 20degrees (the norm being 180 degrees) are also classified as being legally blind.Approximately fifteen percent of those deemed legally blind, by any measure, have no light or form perception. The rest have some vision, from light perception alone to relatively good acuity.Low vision is sometimes used to describe visual acuities from 20/70 to 20/200.[90]
TheMoche people of ancientPeru depicted the blind in their ceramics.[91]
In Greek myth,Tiresias was a prophet famous for hisclairvoyance. According to one myth, he was blinded by the gods as punishment for revealing their secrets, while another holds that he was blinded as punishment after he sawAthena naked while she was bathing. Inthe Odyssey, the one-eyed CyclopsPolyphemus capturesOdysseus, who blinds Polyphemus to escape. In Norse mythology,Loki tricks the blind godHöðr into killing his brotherBaldr, the god of happiness.
TheNew Testament contains numerous instances ofJesus performing miracles to heal the blind. According to the Gospels, Jesus healedthe two blind men of Galilee,the blind man of Bethsaida,the blind man of Jericho andthe man who was born blind.
The parable of theblind men and an elephant has crossed between many religious traditions and is part ofJain,Buddhist,Sufi andHindu lore. In various versions of the tale, a group of blind men (or men in the dark) touch anelephant to learn what it is like. Each one feels a different part, but only one part, such as the side or the tusk. They then compare notes and learn that they are in complete disagreement.
"Three Blind Mice" is a medievalEnglishnursery rhyme about three blind mice whose tails are cut off after chasing the farmer's wife. The work is explicitly incongruous, ending with the commentDid you ever see such a sight in your life, As three blind mice?
PoetJohn Milton, who went blind in mid-life, composed "On His Blindness", a sonnet about coping with blindness. The work posits that[those] who best Bear [God]'s mild yoke, they serve him best.
The Dutch painter and engraverRembrandt often depicted scenes from the apocryphalBook of Tobit, which tells the story of a blind patriarch who is healed by his son, Tobias, with the help of the archangelRaphael.[92]
Slaver-turned-abolitionistJohn Newton composed the hymn "Amazing Grace" about a wretch who"once was lost, but now am found, Was blind, but now I see." Blindness, in this sense, is used both metaphorically (to refer to someone who was ignorant but later became knowledgeable) and literally, as a reference to those healed in the Bible. In the later years of his life, Newton himself would go blind.
H. G. Wells' story "The Country of the Blind" explores what would happen if a sighted man found himself trapped in a country of blind people to emphasise society's attitude to blind people by turning the situation on its head.
José Saramago's novelBlindness describes a sudden mass blindness epidemic, and the main story follows the first group to lose their vision and how they have to adapt to their new disability amidst a decaying society.
Bob Dylan's anti-war song "Blowin' in the Wind" twice alludes to metaphorical blindness:How many times can a man turn his head // and pretend that he just doesn't see... How many times must a man look up // Before he can see the sky?
Contemporary fiction contains numerous well-knownblind characters. Some of these characters can see by means of extraordinary abilities or devices, such as theMarvel Comics superheroDaredevil, who can see via his super-human hearing acuity, orStar Trek'sGeordi La Forge, who can see with the aid of aVISOR, a fictional device that transmits optical signals to his brain.
People who are not blind often imagine that people who are blind share a cultural identity in the way that other minority groups with shared experiences have a distinct culture.[93] Various blind commentators have responded to this perception by explaining that more commonly, blind people integrate with the broader community and culture, and often do not identify blindness as a defining part of their culture.[94][95][96]
People who are blind share the common cultural experience of the many misconceptions sighted people have about living with blindness.[97]
Blind and partially sighted people participate in sports, such asswimming,snow skiing andathletics. Some sports have been invented or adapted for the blind, such asgoalball,association football,cricket,golf,tennis,bowling, andbeep baseball.[98][99] The worldwide authority on sports for the blind is theInternational Blind Sports Federation.[100][101] People with vision impairments have participated in theParalympic Games since the1976 Toronto summer Paralympics.[102]
The word "blind" (adjective and verb) is often used to signify a lack of knowledge of something. For example, ablind date is a date in which the people involved have not previously met; ablind experiment is one in which information is kept from either the experimenter or the participant to mitigate theplacebo effect orobserver bias. The expression "blind leading the blind" refers to incapable people leading other incapable people. Being blind to something means not understanding or being aware of it. A "blind spot" is an area where someone cannot see: for example, where a car driver cannot see because parts of his car's bodywork are in the way; metaphorically, a topic on which an individual is unaware of their own biases, and therefore of the resulting distortions of their own judgements (seeBias blind spot).
A 2008 study tested the effect of usinggene therapy to help restore the sight of patients with a rare form of inherited blindness, known asLeber's congenital amaurosis or LCA.[103] Leber's Congenital Amaurosis damages the light receptors in the retina and usually begins affecting sight in early childhood, with worsening vision until complete blindness around the age of 30. The study used a common cold virus to deliver a normal version of the gene calledRPE65 directly into the eyes of affected patients. All three patients, aged 19, 22 and 25, responded well to the treatment and reported improved vision following the procedure.
Two experimental treatments for retinal problems include a cybernetic replacement and transplant of fetal retinal cells.[104]
There is no high-quality evidence on the effect of assistive technologies on educational outcomes and quality of life in children with low vision as of 2015[update],[105] nor is there evidence on magnifying reading aids in children.[106] Low-vision rehabilitation does not appear to have an important impact on health-related quality of life, though some low-vision rehabilitation interventions, particularly psychological therapies and methods of enhancing vision, may improve vision-related quality of life in people with sight loss.[107]
Statements that certain species ofmammals are "born blind" refers to them being born with their eyes closed and their eyelids fused together; the eyes open later. One example is therabbit. In humans, the eyelids are fused for a while before birth, but open again before the normal birth time; however, verypremature babies are sometimes born with their eyes fused shut, and opening later. Other animals, such as theblind mole rat, are truly blind and rely on other senses.[citation needed]
The theme of blind animals has been a powerful one in literature.Peter Shaffer's Tony Award-winning play,Equus, tells the story of a boy who blinds six horses.Theodore Taylor's classic young adult novel,The Trouble With Tuck, is about a teenage girl, Helen, who trains her blind dog to follow and trust a seeing-eye dog.
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