With determination and will power, everything is possible! And Pranjal Patil definitely proves that. She is India's first visually impaired woman IAS officer. Pranjal hails from Ulhas Nagar in Maharashtra who lost her vision at the age of six.
Source: Pranjal Patil, India's First Blind IAS Officer, Takes Charge as Sub-Collector in Kerala, 2019
Blindness & Low Vision
Blindness & Low Vision
The Blindness and Low Vision Section of the DEEPAK: NDLI Disability Knowledge Portal presents extensive information on all aspects of the life of persons with blindness or visual impairment. This is divided into eight subsections (detailed below). The focus has been kept on Education, Employment, and Training through first three subsections. Caregiving including support services and Institutions dealing with blindness are covered next. Assistive Technology and Android & iOS Apps have become critical assistance in all the activities. These are covered in the following two subsections. Last but not the least, the story of few Achievers, who have excelled in spite of all odds of disability and attitude of the society at large are chronicled as a documentation for achievements of human will.
While the portal is primarily designed for persons with blindness or visual impairment in India, it does cover a lot of information in respect of science, technology, history, and practices that are agnostic to geographic and political boundary.
Prevalence of blindness and visual impairment in population aged ≥50 years in India
Nationwide Representative Blindness Survey was conducted among people aged ≥ 50 years in 31 districts of 24 States/Union territories of India from 2015-19. Out of 93,018 enumerated individuals 85,135 persons were examined. Prevalence was as follows:
Blindness: 1.99%
Severe Visual Impairment (SVI): 1.96%
Moderate Visual Impairment (MVI): 9.81%
Early Visual Impairment (EVI): 12.92%
Moderate Severe Visual Impairment (MSVI): 11.77%
Visual Impairment (VI): 13.76%
Functional Low Vision (FLV): 1.03%
Pinhole blindness: 1.75%
Globally, 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.
This 1 billion people includes those with moderate or severe distance vision impairment or blindness due to
Cataract (94 million)
Unaddressed Refractive Error (88.4 million)
Glaucoma (7.7 million)
Corneal Opacities (4.2 million)
Diabetic Retinopathy (3.9 million), and
Trachoma (2 million)
as well as near vision impairment caused by
Unaddressed Presbyopia (826 million)
In terms of regional differences, the prevalence of distance vision impairment in low- and middle-income regions is estimated to be four times higher than in high-income regions.
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%.
Population growth and ageing are expected to increase the risk that more people acquire vision impairment.
The majority of people with vision impairment and blindness are over the age of 50 years; however, vision loss can affect people of all ages.
Vision impairment poses an enormous global financial burden with the annual global costs of productivity losses associated with vision impairment from uncorrected myopia and presbyopia alone estimated to be US$ 244 billion and US$ 25.4 billion.
Most people with visual impairment are older, and females are more at risk at every age, in every part of the world.
About 87% of the world's visually impaired live in developing countries.
About 85% of all visual impairment is avoidable globally.
Source:
Further Reading:
About Blindness and Visual Impairment
We address few common questions in the sections below:
Blindness and Visual Impairment: Is blindness and visual impairment different? What are grading of visual impairment in the world and in India?
Nature and Prevalence of Vision Loss: What are the primary causes for vision loss? How prevalent are they? Across the world and in India.
Vision with Visual Impairment: What does a person with VI sees?
Common Eye Tests: What are the common tests for eyes? Which test is done for what purpose?
Deafblindness: Being deafblind doesn't necessarily mean that you are totally deaf or totally blind – most individuals who are deafblind have some residual sight and/or hearing. It is a unique disability in its own right
Seeing through the Eyes of the Blind: How do blind and visually impaired people look at life, at themselves, at the sighted and so on? How do they cope with life?
Acronyms and Glossary of Terms
Just because a man lacks the use of his eyes doesn't mean he lacks vision — Stevie Wonder
About the NDLI Portal on Blindness & Low Vision
Globally, 1.1 billion (14.33% of population) people were living with vision loss in 2020:
43 million people are blind (crude prevalence: 0.5%).
295 million have moderate to severe vision impairment (crude prevalence: 3.7%).
258 million have mild vision impairment (crude prevalence: 3.3%).
510 million have near vision impairment (crude prevalence: 6.5%)
Of that, 275 million (19.38% of population) are in India, the highest for any country:
9.2 million people are blind (crude prevalence: 0.65%).
79.0 million have moderate to severe vision impairment (crude prevalence: 5.56%).
49.1 million have mild vision impairment (crude prevalence: 3.45%).
137.7 million have near vision impairment (crude prevalence: 9.68%)
* Crude prevalence is computed with population as a whole - no subdivision or refinement
* Population of the world is taken as 7.674 billion
* Population of India is taken as 1.422 billion
About 25% or one in every four blind or visually impaired person is in India!
This means a huge challenge for India to support these people to lead respectable independent life, be employed with equal opportunity, have access to education, and access to all kinds of information. As a part of National Digital Library of India, this portal attempts to provide access to free information for all people with blindness or low vision and those who are related to them in some way or other.
The portal is organized as follows:
Resources: Links to various digital resources for education (like audiobooks), research (like Visual Atlas), and information are collated here.
Employment: Contrary to the commonly held belief that the blind and visually impaired cannot perform at par with their sighted counterparts at the workplace, we list a galore of opportunity for equal opportunity employment and talk about organizations who actively support and facilitate them.
Training & Vocational: Training and vocational practices are critical for the blind and visually impaired to lead independent life and seek equal opportunity employment. This section provides information on several organizations and programs in this regard.
Caregivers: As it is said - Be empathetic, not sympathetic. Everyone needs empathetic caregivers - parents, family, teachers, support groups, volunteers - for rightful development to reach one's potential. So does the the blind and visually impaired, albeit, often in a different way. In this section we collate information on guidelines & policies, awareness & advocacy initiatives, availability of support groups & services, vision & Braille centers, educative videos, and manufacturers & distributors for the ease of functioning of the caregivers. The information is organized along the following sections:
Guidelines & Policies: Various national and international guidelines and policies may help the caregivers
Awareness & Advocacy: Awareness about the life of a person with blindness or low vision is critical for the sighted people, caregivers and policy makers. And advocacy is regularly needed for establishing proper legal order and policies.
Support Groups: At national and international levels, various support groups help the people with blindness to lead an independent life.
Support Services: Various support services in India, including Low Vision Advisory, Orientation & Mobility, and Talking Book Services, are detailed.
Vision Centers: Various vision centers in India provide free, subsidized or paid quality services for the visually impaired
Braille Production: Producing braille text books and documents at a large scale is a critical need for India having a large number of people with blindness or low vision. Several production centers have been meeting these needs.
Teachers of Visually Impaired (TVI): Training, teaching or mentoring the visually impaired is an non-trivial task. Several resources and options for formal / informal training are discussed.
Dealers: Quality and inexpensive manufacturers and distributors of assistive technology and other solutions for persons with visual impairment in India are critical for caregivers.
Institutions: The Government, its Ministries and various Departments, Institutions, Non-Government Organizations (NGO) etc. are working to support the lives, education, training, employment and livelihood of people with blindness and visual impairment.
International Organizations: Institutions - Government as well as private - across the world, primarily in USA and Europe, that work for the blind that can be of assistance to the people with blindness and visual impairment in India.
National Institutions & Composite Regional Centers in India: Activities of Institutions of the GoI and the regional centers in different states.
NGOs in India: Activities of the NGOs across India and a few International NGOs with centers and / or linkages in India.
Special Schools in India: Public and Private Special Schools for the students with blindness and visual impairment across various states of India.
Assistive Technology: People with Blindness or Low Vision are challenged in one - the vision - sense. Appropriate use of technology can make up for this gap in one or more of the following ways:
Visual Enhancement: The existing visual acuity can be improved with the use of glasses, magnifiers etc.
Visual Substitution: It can help one see with one or more non-visual senses. Like a text can be Braille coded (reading by touch), it can be read out loud (reading by hearing), a map or geometric drawing can be tactile with raised lines (reading diagrams by touch), nearness of obstacles could be sensed by pressures on the tongue (sensing by haptic), and so on.
Visual Replacement: Replacement could work in a wide range from eye donation (retina replacement) to optical prostheses and so on. The core idea is to replace or bypass the existing vision system with alternate with AT.
We review AT for Vision in the aspects of reading and writing Braille / textual information, graphical or diagrammatic information, generic aids to vision improvement, navigation (orienting oneself and be mobile), support in education, games and leisure activities and day-to-day life through the following sections:
Read & Write Braille: We take a look at Braille System and its readers and writers. We also present Braille printing options.
Read & Write Text: We look at various screen reading options for normal display text, OCRs, Digital Pens, Notetakers, Large Print, and importantly the accessibility formats and accessibility needs of the webpages.
Read & Write Images: While Braille and Screen reading mostly addresses the issues of text-based communication, images remain a challenge for the blind and the visually impaired. Though raised line methods were used in the world's first complete atlas for the blind published in the United States in 1837, it has taken several decades for it to be a large scale affordable technology. We look at the options today for maps, geometric figures etc. and also the exploratory use of tactile graphics for arts.
Low Vision Aids: Glasses have been used for correcting refractive errors of the eye (short and long sights) from time immemorial. Over time better lens material have been introduced along with a range of smart glasses that do lot more than just magnification.
Orientation & Mobility: Moving in a 3D space requires orientation and navigation capabilities. Dogs and Cane have traditionally been the friend of a blind for this. With AT, several Electronic Travel Aids (ETAs), Electronic Orientation Aids (EOAs) and Mixed EO&TAs have been introduced. They can be external to the user and / or can be carried by the user (for example, infrared light transmitters and handheld receivers). We explore various option for outdoor as well as indoor navigation, and a range of new innovations being worked on.
Education: Education is a key need for every person. So for the blind and visually impaired though there are more obstacles for a challenged student to be at par with her sighted counterpart. We discuss ATs for Reading, Writing, Mathematics, Science and Social Studies, Computer Access, O & M, and even Art, Music and Physical Education. We also refer to supportive pedagogy, processes and tools in this regard.
In every section of AT we start with the general information on the issues and approach of AT, history of development and challenges, then present the available ATs and solutions, and finally conclude with the innovations, research, and future of the respective ATs.
Android & iOS Apps: Apps have changed the way we live today and they have been a great boon for the people with blindness and visual impairment to enhance their accessibility in various spheres of activities and ease of functioning and degree of independence in life. While both Android and iOS phones have support for a range of accessibility, a plethora of apps help the user in the various areas including, but not limited to, the following:
Scanner, Reader, and Writer Apps
Magnifier Apps
Navigation, Mobility and Orientation Apps
Office and School Apps
Job Apps
Lifestyle Apps
Achievers: Whether it is government service like IFS / IAS, it is music or drama, it is sports, it is service to people - the people with blindness and visual impairment have achieved a lot, reached heights, and inspired others.
The only thing worse than being blind is having sight but no vision — Helen Keller
A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen, who developed the chart in 1862.
A common Snellen chart is printed with eleven lines of block letters. In VA testing on Snellen chart, person normally sits at a distance of 6m from the chart on which letters of standard decreasing size are there in rows. Top line has a single letter which should be readable at a distance of 60m. Visual acuity is recorded as a ratio with numerator of 6 (distance at which patient sits) and the denominator of the smallest possible size being read by the patient. For example, a vision record of 6/60 means that patient sitting at 6m could read letter in top line only, which should normally be read at 60m. Instead of distances being in meters, it may also be measured in feet. 6m is about 20'. Therefore, a vision of 6/6 in meters, is equivalent to a vision of 20/20 in feet. Similarly, a vision of 6/60 in meters, is equal to 20/200 in feet.
Visual Acuity commonly refers to the clarity of vision, but technically rates an examinee's ability to recognize small details with precision. Visual acuity is dependent on optical and neural factors:
the sharpness of the retinal image within the eye
the health and functioning of the retina, and
the sensitivity of the interpretative faculty of the brain
It is a measurement determined by the letter chart tests we take when we get our eyes checked; the number represents your eyes’ clarity or sharpness. For example, a person with a visual acuity measurement of 20/70, who is 20' away from an eye chart sees what a person with 20/20 vision can see from 70' away.
A logMAR chart (Logarithm of the Minimum Angle of Resolution) is a chart consisting of rows of letters that is used by ophthalmologists, orthoptists, optometrists, and vision scientists to estimate visual acuity. The chart was developed at the National Vision Research Institute of Australia in 1976, and is designed to enable a more accurate estimate of acuity than do other charts like Snellen chart.
When using a LogMAR chart, visual acuity is scored with reference to the logarithm of the minimum angle of resolution. An observer who can resolve details as small as 1 minute of visual angle scores LogMAR 0, since the base-10 logarithm of 1 is 0; an observer who can resolve details as small as 2 minutes of visual angle (i.e., reduced acuity) scores LogMAR 0.3, since the base-10 logarithm of 2 is near-approximately 0.3; and so on.
Visual Acuity Testing is explained nicely in this YouTube video.
Blindness and Visual Impairment
Subjectively or qualitatively, lack of normal vision can be defined as:
Visual Impairment: A decrease in the ability to see to a certain degree that causes problems not fixable by usual means, such as glasses
Blindness: The state of being unable to see due to injury, disease or genetic condition
Objectively and quantitively, however, it is defined is relations to someone's Visual Acuity (VA is explained on left).
Different nations in the world follow different classification or grading for loss of vision. So we present definitions from WHO, US and India.
For International comparison, WHO has defined blindness at the level of 3/60 or inability to count fingers at a distance of 3 meters or 10 feet.
The International Classification of Diseases 11 (ICD-11, 2018) classifies vision impairment into two groups:
Distance vision impairment:
Mild – visual acuity worse than 6/12 to 6/18
Moderate – visual acuity worse than 6/18 to 6/60
Severe – visual acuity worse than 6/60 to 3/60
Blindness – visual acuity worse than 3/60
Near vision impairment:
Near visual acuity worse than N6 or M.08 at 40cm.
A person’s experience of vision impairment varies depending upon many different factors. This includes, for example, the availability of prevention and treatment interventions, access to vision rehabilitation (including assistive products such as glasses or white canes), and whether the person experiences problems with inaccessible buildings, transport and information.
Blindness and Visual Impairment Definitions in US
In the U.S., there are four terms used to describe different levels of vision impairment and blindness:
Partially sighted means a person has partial vision, either in one or both eyes.
Low vision refers to a severe visual impairment in which visual acuity is 20/70 or poorer in the better-seeing eye and cannot improve with glasses or contacts.
Legally blind means a person has a corrected vision of 20/200 in their best-seeing eye. If visual aids such as glasses can correct a person’s vision to 20/20, they are not considered legally blind.
Totally blind refers to a complete loss of sight.
Blindness and Visual Impairment Definitions in India
Technically, blindness and visual impairment are classified as follows in India:
Blindness: VA < 3/60 in better eye with available correction
Blindness (BCVA/Pinhole <3/60): Best corrected VA < 3/60 in better eye
Severe Visual Impairment (SVI): VA < 6/60 – 3/60 in better eye with available correction
Moderate Visual Impairment (MVI): VA < 6/18 – 6/60 in better eye with available correction
Early Visual Impairment (EVI): VA < 6/12 – 6/18 in better eye with available correction
Moderate Severe Visual Impairment (MSVI): VA < 6/18 – 3/60 in better eye with available correction
Visual Impairment (VI): VA < 6/18 in better eye with available correction
Functional Low Vision (FLV): A person with impairment of visual functioning even after treatment and/or standard refractive correction, and a VA of less than 6/18 to light perception, or a visual field of less than 10 degree from the point of fixation, but who uses, or is potentially able to use, vision for planning and/or execution of a task.
* BCVA: Best Corrected Visual Acuity
Functionally, blindness and visual impairment are classified as follows in India by National Programme for Control of Blindness (NPCB)
Inability of a person to count fingers from a distance of 6m or 20'
Vision 6/60 or less with the best possible spectacle correction
Diminution of field vision to 20 feet or less in better eye
There are two main categories of visual impairment:
Being partially sighted or sight impaired – where the level of sight loss is moderate
Severe sight impairment (blindness) – where the level of sight loss is so severe that activities that rely on eyesight become impossible.
Types of Blindness:
Economic blindness: Inability of a person to count fingers from a distance of 6m or 20' technical Definition
Social blindness: Vision 3/60 or diminution of field of vision to 10°
Manifest blindness: Vision 1/60 to just perception of light
Absolute blindness: No perception of light
Curable blindness: That stage of blindness where the damage is reversible by prompt management, for example, cataract
Preventable blindness: The loss of blindness that could have been completely prevented by institution of effective preventive or prophylactic measures, for example, xerophthalmia, trachoma and glaucoma
Avoidable blindness: The sum total of preventable or curable blindness is often referred to as avoidable blindness.
Congenital or Adventitious Blindness
Visual impairments are further classified as congenital or adventitious.
Congenital refers to loss of vision present at birth (or within an early age like 5 years). Some of the common causes of congenital visual impairment are:
Prematurity
Genetic diseases
Prenatal and perinatal infections
Maternal substance abuse
Adventitious refers to loss of vision acquired after birth (or after 5 years or so) as a result of illness or accident. The age and level of development of the child before the onset of the visual impairment influences the child’s ability to acquire skills and concepts.
Children with congenital blindness may have difficulty acquiring concepts, while children with adventitious blindness may retain sufficient visual memory to benefit from visual descriptions. Although two children may be medically assessed as having the same diagnosis and visual acuity, they may each learn and function in different ways. A child's vision may fluctuate or may be temporarily influenced by such factors as:
Nature of visual impairment
Fatigue
Glare
Inappropriate lighting
Medication
General health
Sources:
Further Reading:
What is the difference between Visually Impairment and Blindness?
WHAT IS THE DIFFERENCE BETWEEN VISUALLY IMPAIRED AND BLIND | Disabilities are a Spectrum, Visually Impaired Designer, 2020
Visual Impairment- blindness & low vision D.ed 1st year (Hindi), Divya Study Time, 2020
Differences of Blind and Visually Impaired, Health Is Wealth, 2019
Visual Impairment (Hindi), vmouonline, 2015
Nature and Prevalence of Vision Loss
Some changes in vision are normal as we grow older. This section would help understand these vision changes, alert one to abnormal changes in vision, and give information about the primary causes of vision loss for adults, including cataracts, uncorrected refractive error, glaucoma, macular degeneration, and diabetic retinopathy.
Cataracts (White Blindness, मोतियाबिंद): A cataract is a progressive cloudiness, hardening, and yellowing of the normally transparent lens of the eye.
The world’s most common cause of blindness.
A cataract is a clouding of the eyes’ lens, and can occur at any age and for a variety of reasons, including genetics, age, trauma, skin disease, radiation, drug use and medication.
It can take just 15 minutes to perform a sight-restoring cataract operation.
Posterior Capsule Opacification (PCO) is the most common complication of cataract surgery. At present the only means of treating cataract is by surgical intervention, and this initially restores high visual quality. Unfortunately, PCO develops in a significant proportion of patients to such an extent that a secondary loss of vision occurs.
Uncorrected refractive error (URE): Refractive errors can happen when the eyeball grows or reduces in length, when the cornea changes shape, or with age.
URE is the second most common reason behind impaired vision.
RE causes Blurred or distorted vision, Headaches, squinting and eye strain, Difficulty reading, Double vision, ‘Halos’ around bright lights or Haziness. There are four types of refractive conditions including three REs:
Emmetropia: Clear vision without glasses or contacts
Myopia (Near Sightedness or Short Sightedness): Usually an inherited eye condition, myopia causes far away images to be seen blurred, while images are clear up close. This happens because the distance between the cornea and the retina is too long. Myopia is usually identified during childhood and exacerbated during puberty, when the body goes through a lot of change.
Correction is usually done using glasses or contact lenses.
Hyperopia / Hypermetropia (Far Sightedness or Long Sightedness): This occurs when the distance between the cornea and the retina is too short. We experience hyperopia on a scale; mild levels make images appear blurred close up, and clear when they're far away. For individuals with high levels of hyperopia, images can be blurry at all distances.
Solved with eyeglasses, specialized glasses, surgery and contact lenses.
Presbyopia (Loss of Near Vision with Age): As we age, our lenses become rigid, allowing less close-range focusing flexibility. Signs of presbyopia start to emerge from around 35-45 years of age.
It can be corrected by using reading glasses.
Astigmatism (Uneven Focus): When the cornea has asymmetric stigmatism (uneven curvature), we call that astigmatism. Rather than the equal curves of a sphere, the front surface of the eye ends up more like a football. This causes the light coming through the cornea to focus unequally on the retina, resulting in a distorted or stretched out image. In most cases, a person with astigmatism will have blurred vision both near and far.
Corrected with glasses, contact lenses or refractive surgery.
Glaucoma (Black Blindness): Glaucoma is an eye disease in which the normal fluid pressure inside the eyes slowly rises, leading to vision loss or even blindness.
The third leading cause of blindness, glaucoma can be treated with medication.
An operation can help reduce its effects, but it’s not curable.
There are two major categories of glaucoma:
Open angle glaucoma tends to progress over long period of time and typically goes unnoticed until the disease is very advanced. In this, something is wrong with the drainage angle of the eye — even though it appears to be open and often appears normal on a clinical exam as well.
It is the most common form of glaucoma and usually results from aging of the drainage channel. However, younger people can also get this type of glaucoma.
Closed angle glaucoma is a mechanical problem where the drainage angle is obstructed by the iris. It tends to appear suddenly and is quite painful. While vision loss tends to occur quickly, the associated pain means that most people seek medical attention before permanent damage occurs.
Corneal Opacity: Also called Corneal blindness. The human cornea is a transparent membrane which allows light to pass through it. The word corneal opacification literally means loss of normal transparency of cornea. The term corneal opacity is used particularly for the loss of transparency of cornea due to scarring.
It is the fourth most common cause of blindness all over the world, accounting for over 5% of the total blind population.
It is corrected by corneal transplant.
Diabetic Retinopathy: Diabetic retinopathy (DR), also known as diabetic eye disease (DED), occurs when diabetes damages the small blood cells in the retina due to diabetes mellitus. It can cause blind spots, blurring, and vision loss.
It is a leading cause of blindness in developed countries.
DR affects up to 80% of those who have had diabetes for 20 years or more.
At least 90% of new cases could be reduced with proper treatment and monitoring of the eyes.
Macular Degeneration: Age-Related Macular Degeneration (AMD) is a gradual, progressive, painless deterioration of the macula, which is the small area in the center of the retina that gives us our detail vision.
Commonly referred to as AMD, age-related macular degeneration is the leading cause of impairment of reading and close-up vision among people over 65. AMD results in damage to one’s central vision, which is needed for common daily tasks such as reading and driving. According to estimates, 1.8 million Americans aged 40 years and older are affected by AMD and an additional 7.3 million are at substantial risk of developing AMD.
Posterior Segment Eye Disease (PSED): PSED is commonly defined as diseases of the retina, choroid and optic nerve and primarily includes: glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR)
Trachoma: About 2 million people have impaired vision or are blind because of trachoma – the most widespread infectious cause of blindness. It cause the inside of the eyelid to scar, making the eyelashes turn inward. These, in turn, scratch the cornea, leading to irreversible blindness.
In its earlier stages, trachoma is treated with antibiotics and can be prevented by keeping the face clean. In the final stage of the illness, surgery on the eyelid is the only way to avoid loss of sight.
Nyctalopia: Also called Night-Blindness, is a condition making it difficult or impossible to see in relatively low light. It is a symptom of several eye diseases. Night blindness may exist from birth, or be caused by injury or malnutrition. The most common cause of nyctalopia is retinitis pigmentosa, a disorder in which the rod cells in the retina gradually lose their ability to respond to the light. Another cause is a deficiency of retinol, or vitamin A, found in fish oils, liver and dairy products.
Xerophthalmia: Xerophthalmia is a medical condition in which the eye fails to produce tears. It may be caused by vitamin A (Axerophthol) deficiency, which is sometimes used to describe that condition, although there may be other causes.
Color blindness: Color blindness (color vision deficiency) is the decreased ability to see color or differences in color. It can impair tasks such as selecting ripe fruit, choosing clothing, and reading traffic lights. People with total color blindness (achromatopsia) may also be uncomfortable in bright environments and have decreased visual acuity. The most common cause of color blindness is an inherited problem in the development of one or more of the three sets of the eyes' cone cells, which sense color. Among humans, males are more likely to be color blind than females, because the genes responsible for the most common forms of color blindness are on the X chromosome.
River blindness: Onchocerciasis, or River Blindness, is a parasitic disease caused by onchocerca volvulus. It is characterized by itchy skin and severe swelling in the eye which results in impaired vision, including permanent blindness. River blindness is on the retreat worldwide thanks to the widespread distribution of the drug Mectizan.
Stargardt Disease: It is an inherited disorder of the retina — the tissue at the back of the eye that senses light. The disease typically causes vision loss during childhood or adolescence, although in some forms, vision loss may not be noticed until later in adulthood. It is rare for people with the disease to become completely blind. For most people, vision loss progresses slowly over time to 20/200 or worse.
The most common symptom of Stargardt disease is variable, often slow loss of central vision in both eyes. People with the disease might notice gray, black, or hazy spots in the center of their vision, or that it takes longer than usual for their eyes to adjust when moving from light to dark environments. Their eyes may be more sensitive to bright light. Some people also develop color blindness later in the disease.
Sources:
Blindness, Vikaspedia
Further Reading:
Prevalence of Blindness in India
According to the National blindness survey (2006-2007, the prevalence of blindness in India is 8% in individuals above 50 years of age in India. The major reasons for prevalence of blindness in India are:
The overall increase in the size of the population
The life expectancy for both males and females has steadily increased
A major proportion of aged population in rural areas have poor access to eye care facilities in India
Inadequate availability of trained health personnel
The poor nutritional status of mothers and young children predisposes the pre-school children to nutrition blindness.
Adverse environmental conditions and domestic unhygienic conditions predispose to high infection rates
Lack of community awareness and poor health seeking behavior
The prevalence of myths and misconception about surgeries
Source
Blindness, Vikaspedia
Further Reading:
Visual Impairment Handbook - 2nd Edition by Bhushan Punani and Nandini Rawal, Blind People’s Association, 2000
Vision with Visual Impairment
It is naturally, very difficult to get to see what people see under VI. Some artefacts can be mapped (like invisible areas, blind spots, etc.), some have been sketched from verbal description, some have been drawn by people under VI, and there have been attempts to simulate the VI vision. We present for some of the VI categories.
Cataract Vision
Blurriness
Glare
Double Image
Loss of Color
Second Sight - unusual sharpness
Nuclear Sclerotic Cataract
This image represents the view through a "nuclear sclerotic" type of cataract. Note that in addition to the image being blurred, it is also dim and less colorful than the normal view. The color blue is especially obscured by this common type of cataract.
Posterior Subscapular Cataract
The "posterior subcapsular" type of cataract often affects younger individuals, and those with diabetes or on steroids. There may be severe glare with this type of cataract, with halos and starbursts being visible from point sources of light.
Uncorrected Refractive Error (URE) Vision
Models of Refractive Error
Common Corrective Lens
Myopia
Hyperopia
Comparative Vision
Refractive Error: Common Vision Problems
Astigmatism in day & in night
Astigmatic View
Astigmatism: Corrected
Glaucoma Vision
Laser Doppler Imaging (LDI) reveals arterial blood flow reversal in neovascular glaucoma. The color change of the Doppler image in the central retinal artery during the cardiac cycle indicates arterial flow reversal.
Optic nerve in glaucoma
Normal View
Glaucoma View
Normal View
Glaucoma View
Blind Spots in early Glaucoma
Glaucoma: Severe loss of vision
Diabetic Retinopathy Vision
Comparative View
Normal View
DR View
Depiction of diabetic retinopathy
Macular Degeneration (AMD) Vision
Normal View
Early Wet Type
Severe Wet Type
Macular Degeneration
Color Blind Visions
Protanopia and protanomaly or red deficiencies
Full Color Vision Image
Deuteranopia and deuteranomaly or green deficiencies
Tritanopia and tritanomaly or blue deficiencies
Full Color Vision Image
Rod monochromacy or achromacy or no color
Portion of the New York City public transportation map in color
Portion of the New York City public transportation map in monochrome
Retina Detachment, Color Blind, Night Blind, and other Visions
Color Blindness
These images demonstrate how individuals with normal color vision, and abnormal color vision, might view this color vision test. Those with normal vision would see the number "3" as shown on the left. With mild color blindness (as is present in about 8% of males), the number may be misread as a "5", as shown in the middle. With total color blindness, no number or pattern is visible, as shown on the right
Ophthalmic Migraine
As an effect of migraine headache, the area of jagged, zigzag lights are constantly in motion, flashing over a 15 to 30 minute time frame. The area involved often starts small near the center of the vision, then moves outward slowly. There is a scotoma, or a blink spot, in the area of the disturbance, which is seen in the same field of vision of both eyes. A migraine headache may follow this aura.
Vitreous Hemorrhage
Blood veil over the vision due to minor hemorrhage into the vitreous body of the eye from diabetic retinopathy, retinal tears, vitreous detachment, and sickle cell retinopathy, etc.
Stargardt Disease
Color fundus photography image of a patient showing a central macular scar with some pigmentary changes and surrounding perimacular flecks.
Fundus auto-fluorescence image of a patient having Stargardt
Double Vision
Double vision looking down a road leading into Shockoe Slip, in downtown Richmond. In this case, the double vision is oriented horizontally (side by side). This could occur with dysfunction of certain nerves controlling eye movement, or with thyroid related orbital problems.
Nyctalopia
Retinal Detachment
Vision is lost in the area of detachment and distorted at the margin
River Blindness
Trachoma - swollen eye
Vision Simulations www.visionaware.org
Simulation of Vision Conditions
Vision simulation is one way to understand how the world is experienced by someone with a visual impairment. Although no simulation can mimic exactly a vision loss, the following pictures are meant to give the viewer some idea of what certain eye diseases are like.
Source:
Visual Simulations, Ohio Lions Eye Research Foundation
Simulations of Eye Disorders, Richmond Eye Associates
Vision Simulation Video, VisionAware
Normal View
Diabetic Retinopathy
Age-related Macular Degeneration
Cataract
Normal View
Glaucoma and Retinitis Pigmentosa
Ring or Donut Scotoma
Left Field Homonymous Hemianopia
Normal View
Left Field Homonymous Hemianopia with Macular Sparing
Vision in the Elderly
Floaters
Normal View
Migraine Fortification Phenomenon
Scotomas Caused by Pituitary Tumors (Lesions)
(Left Eye View)
Scotomas Caused by Pituitary Tumors (Lesions)
(Right Eye View)
Visual Acuity tests by Snellen Chart
Normal (Above) sees '8'
Ishihara Color Vision Test
Colorblind (Below) sees no '8'
Cover Test
Muscles of the Right Eye - Ocular Motility Test
Sir William Bowman (1816-92)
Sir Bowman was the first to investigate the shadow effect that paved the way for retinoscopy. He observed an interesting shadow (a linear fundus reflex) in 1859. Bowman was able to describe a method of detecting, if not yet quantifying, levels of astigmatism in eyes with keratoconus (a misshapen cornea). Bowman considered his technique to be primarily a diagnostic one - to detect whether or not a cornea was cone-shaped.
In 1873 the French ophthalmologist Ferdinand Cuignet (b.1823) used a simple ophthalmoscope to compare the variable reflexes in eyes which subjective testing had already determined to be experiencing different refractive errors. This was a qualitative test.
By observing the size, brightness, speed or direction of the reflex Cuignet could now classify the patient's error in simple categories such as myopia, hyperopia or astigmatism. Somewhat misleadingly he called his technique keratoscopie, thinking that the cornea was responsible for his observations.
In 1878 Cuignet's pupil, M. Mengin, published an accurate explanation that the source of the reflex was the fundus rather than the cornea.
Finally, in 1880, H. Parent (1849-1924) introduced the quantitative refraction test. It was now possible to measure the exact amount of refractive error using lenses. He also coined the term retinoscopie.
Duochrome Test
Goldmann Applanation Tonometry, UVA Health - School of Medicine, 2021
Dilated Fundus
Common Eye Tests
Eye tests range from simple ones, like having you identify letters on an eye chart, to complex tests, such as using digital imaging devices to see and evaluate tiny blood vessels and other structures inside your eyes.
Visual Acuity Test
Among the first tests performed in a comprehensive eye exam are visual acuity tests that measure the sharpness of your eyesight.
These usually are performed using a projected eye chart to measure your distance visual acuity and a small, hand-held acuity chart to measure your visual acuity at a normal reading distance.
Color Blindness Test
A screening test that checks your color vision often is performed early in a comprehensive eye exam to rule out color blindness.
In addition to detecting hereditary color vision deficiencies, color blind tests also can alert your eye doctor to possible eye health problems that may affect your color vision.
Cover Test
While there are many ways for your eye doctor to check how your eyes work together, the cover test is the simplest and most common.
During a cover test, your eye doctor will ask you to focus on a small object across the room and will then cover each of your eyes alternately while you stare at the target. The test is then repeated with you looking at a near object.
During these tests, your eye doctor will assess whether the uncovered eye must move to pick up the fixation target, which could indicate strabismus or a more subtle binocular vision problem that could cause eye strain or amblyopia (lazy eye).
Ocular Motility (Eye Movements) Test
Ocular motility testing is performed to determine how well your eyes can follow a moving object and/or quickly move between and accurately fixate on two separate targets.
To test smooth eye movements (pursuits), your eye doctor will have you hold your head still and ask you to follow the slow movement of a hand-held light or other target with just your eyes.
To evaluate quick eye movements (saccades), your doctor might have you move your eyes back and forth between two targets positioned some distance apart from each other.
Problems with eye movements can cause eye strain, headaches, blurry vision and other problems.
9 Diagnostic Positions of Gaze for Ocular Motility Test
Stereopsis (Depth Perception) Test
Stereopsis is the term used to describe eye teaming that enables normal depth perception and appreciation of the 3-dimensional nature of objects.
Random dot stereo target. The left box would be the patient's view without polarized lenses. The right box is what a patient with normal stereopsis would see (can you see the circle?)
In one commonly used stereopsis test, you wear a pair of "3D" glasses and look at a booklet of test patterns. Each pattern has four small circles, and your task is to point out which circle in each pattern looks closer to you than the other three circles.
If you can correctly identify the closer circle in each pattern, you likely have excellent eye teaming skills that should enable you to experience normal depth perception.
Contour test. The patient is instructed to identify the one target that appears to be popping out of the page. Some very high depth targets (first left) have a single-eye (monocular cues) that may give away the answer, even without using the polarized lenses. The 2nd image is an impression of what a patient with normal stereopsis would see. Lower depth targets are more difficult (3rd and 4th image)
Retinoscopy
In this test, your eye doctor will sit about arm’s length from you with the room lights dimmed and shine a bright light into your eyes with a hand-held instrument. This procedure can tell your doctor if you have a cataract or a significant distortion of the shape of your cornea (keratoconus).
Retinoscopy also can be used to give your doctor an approximation of your eyeglass prescription by seeing how the light reflections change as different powered lenses are placed in front of your eyes.
Refraction
This is the test that your eye doctor uses to determine your eyeglass prescription. During a manual refraction, your doctor puts an instrument called a phoropter in front of your eyes and shows you a series of lens choices. He or she will then ask you which of the two lenses in each choice looks clearer. Based on your answers, the best lens power will be fine-tuned until the eyeglass prescription that gives you the clearest vision is determined.
The refraction also determines how much nearsightedness, farsightedness or astigmatism you have.
Duochrome Test
This test is commonly used to refine the final sphere in refraction, which makes use of the longitudinal chromatic aberration of the eye. Because of the chromatic aberration of the eye, the shorter wavelengths (green) are focused in front of the longer red wavelengths.
The patient is asked to compare the clarity of the letters on the green and the red side. If the letters of the green side are clearer +0.25 D sphere is added and if the letters on the red side are clearer -0.25 D sphere is added. With optimal spherical correction, the letters on the red and green halves of the chart appear equally clear.
Autorefractors and Aberrometers
Your eye doctor also may use an autorefractor or aberrometer to automatically estimate your eyeglass prescription. With both devices, a chin rest stabilizes your head while you look into the instrument at a pinpoint of light or a detailed image. An autorefractor determines the lens power required to accurately focus light on your retina. An aberrometer uses advanced wave front technology to detect even obscure vision errors based on the way light travels through your eye.
Slit Lamp Exam
The slit lamp is a microscope used by your doctor to examine the health of your eyes. It gives a highly magnified view of the structures of your eye. This allows for a thorough evaluation of the both the front and back of your eyes, including the cornea, conjunctiva, iris, lens and retina.
Tonometry (Glaucoma) Tests
This test is used to measure the internal pressure of your eye, called Intra-Ocular Pressure (IOP). Elevated pressure can be indicative of glaucoma. Glaucoma is a disease which causes damage to the optic nerve and can lead to vision loss. Elevated pressure in your eye is not painful or uncomfortable. The only way to detect it is by special testing, making it that much more important to come in on a yearly basis for your comprehensive eye examination.
Dilated Fundus / Pupil Dilation
Dilation is an important part of your eye exam as it allows for thorough evaluation of the back of your eye, specifically the retina. The pupils are widened with the use of an eye drop. Difficulty focusing and increased light sensitivity are the main side effects of the drops, lasting between 2-4 hours. Disposable sunglasses will be provided to you prior to leaving the office, ensuring visual comfort during your drive home.
Thorough examination of your retina is essential for people of all ages. It is especially important for people who have risk factors such as hypertension, diabetes or a family history of eye disease.
Visual Field Test
In some cases, your eye doctor may want to check for the possible presence of blind spots or restrictions of your peripheral or side vision by performing a visual field test. These types of blind spots can indicate eye diseases such as glaucoma or brain damage caused by a stroke or tumor.
Source:
Laura Dewey Lynn Bridgman (1829 – 1889) is known as the first deaf-blind American child to gain a significant education in the English language, fifty years before the more famous Helen Keller.
Bridgman was left deaf-blind at the age of two after contracting scarlet fever. She was educated at the Perkins Institution for the Blind where she learned to read and communicate using Braille and the manual alphabet
Helen Adams Keller (1880 – 1968) was an American author, disability rights advocate, political activist and lecturer.
Born in West Tuscumbia, Alabama, she lost her sight and hearing after a bout of illness at the age of nineteen months. Her first teacher and life-long companion Anne Sullivan taught her language, including reading and writing. She attended Radcliffe College of Harvard University and became the first deafblind person to earn a Bachelor of Arts degree. She worked for AFB from 1924 until 1968, during which time she toured the United States and traveled to 35 countries around the globe advocating for those with vision loss.
Deafblindness
Being deafblind is recognized as a unique disability in its own right. It doesn't necessarily mean that you are totally deaf or totally blind – most individuals who are deafblind have some residual sight and/or hearing.
It’s not about the amount of sight and hearing you have; it’s about the combined impact of having more than one sensory impairment.
Dual-Sensory Impairment (DSI) or Multi-Sensory Impairment (MSI) are other terms that may be used if you have both sight and hearing impairments.
Everybody with a combined sight and hearing impairment connects, communicates and experiences the world differently. The approach to support will vary, especially between the two broad types of deafblindness explained below. But with the right support, you can lead a connected and fulfilled life.
Types of deafblindness
Congenital deafblindness is a term used if a person is born with a sight and hearing impairment. This may be due to infections during pregnancy, premature birth, birth trauma and rare genetic conditions.
Acquired deafblindness is a term used if a person experiences sight and hearing loss later in life. Anyone can become deafblind at any time through illness, accident or as a result of ageing.
Causes of deafblindness
Medical complications during pregnancy and birth, including cerebral palsy.
A range of syndromes, including Usher syndrome, CHARGE syndrome, congenital rubella syndrome and Down Syndrome.
Premature birth.
Illness and accidents.
Sensory loss as a result of ageing.
These causes mean you may have:
A mild to profound sight and hearing impairment, with or without other significant disabilities.
Changing conditions which cause impairment to sight and hearing.
Sight and hearing impairments caused by difficulties with the structure or function of the brain, e.g. Cerebral Visual Impairment (CVI).
Definition of Deafblindness in India
A combination of hearing and visual impairments causing such severe communication, development, and educational problems that the child cannot be accommodated in either a programme specifically for the deaf or a programme specifically for the blind.
Deafblindness is classified as follows:
Totally deaf and totally blind
Totally deaf and partially blind
Totally blind and partially deaf
Partially blind and partially deaf
There are several definitions of deafblindness. But most of the definitions include the following characteristics:
Simultaneous presence of vision and hearing impairment which may vary in degrees
Does not imply total loss of either vision or hearing
Communication is most severely affected
Highly individualized training is needed to cope with the condition
The world is much narrower as the distant senses are affected, and it is usually within the arm’s reach.
Affects person in totality
Associated medical conditions with hearing and visual loss may be present
Persons with deafblindness can be categorized into four types:
Those who are born deaf and blind, which can happen if the mother, inter alia, contacted Rubella (German measles) during pregnancy.
Those who were born deaf and then lost their sight. This is often caused by the Usher Syndrome – deafness followed by a decrease in sight because of retinitis pigmentosa (tunnel vision). Other reasons for loss of vision later in life could also be cataract, glaucoma, accidental injury or trauma.
Those who were born blind and then lost their hearing due to severe infections, accidents or trauma.
The adventitious deafblind, as a result of old age, or through an illness or accident later in life.
Some Indian Achievers
Dr. Rajendra Singh Sethi: the first person with deafblindness to acquire a doctorate degree, editor of National Association for the Blind (NAB) India’s magazine.
Shri. Anindyo Bhattacharya: a person with deafblindness, lives in New York and works in Helen Keller National Centre
Shri. Rajesh Sheth: a person with deafblindness in Limbdi, Gujarat who owns and manages a sweet shop.
Shri.Zamir Dhale: a person with deafblindness brought up in Mumbai and works as Advocacy Officer in Sense International (India)
Shri. Pradip Sinha: a person with deafblindness, working as an Instructor in the computerized mini braille press at Helen Keller Institute for Deaf and Deafblind, Mumbai.
Mr. Mahadevan: a person with deafblindess, working as an instructor of sign language for teacher trainees and possessing a National Award for Best Special Employee, awarded by govt. of India in the year 2011.
Mr. Miranda: a person with deafblindness a first person to appear before University Grant commission to clear National Eligibility Test (NET) after completing Master in Sociology and Master in Public Administration. He is the first one to get UGC NET question paper in Braille format.
Sources
Further reading
Seeing through the Eyes of the People with Blindness
Featured Blind/Low Vision People, Blind to Billionaire: A playlist of videos on featured low vision people on how do they look at themselves and the world
Being Married to a Blind Person, Blind to Billionaire: A playlist of videos related to relationships and being married to someone who is blind or disabled. We discuss what it is like to be the sighted partner and the blind spouse. We also discuss tips and tricks to make things easier. Enjoy!
Live Streams, Blind to Billionaire: A playlist of videos from live streams on experience sharing
Infrastructure for the Disabled OR Disabled Infrastructure, Satyameva Jayata, Episode 6: Persons with disabilities
The state of Infra design in India
Universal Design: Inclusive Design for Blindness
While no one city is the perfect model of universal design, Christopher Meyer (legally blind) believes communities are taking strides to accommodate those with disabilities. In Germany, individuals who are “significantly impaired in their freedom of movement by road” may use public transportation for free. (Germany is also home to Seehotel Rheinsberg, a luxury hotel built especially for people with disabilities. It is the country’s largest barrier-free hotel, and its rooms, recreation areas, and reception desk are designed for wheelchair users.)
Tactile paving is another way to help individuals who are visually impaired. These textured paving blocks originated in Japan and provide underfoot information at pedestrian crossings and other critical transportation areas (e.g. railway platforms). Normally sighted individuals may describe the blocks as “bumpy,” but for those with impaired sight, these tactile cues say, “You’re approaching a curb cut,” “There’s a staircase ahead,” and “Wait here for the train.” Tactile paving blocks often come in high-contrast colors and can also indicate the direction of travel.
“They tell you how to walk and where to walk,” says Meyer. “I don’t think it’s the solution, but it’s one way to help contextualize a space.”
Source
DESIGN FOR THE BLIND: ARCHITECTURE FOR THE VISUALLY IMPAIRED
Inclusive Design of Workplaces for People who are Low Vision or Blind
Further reading
Touching Videos
Husband fakes blindness for loving wife.mp4Husband fakes blindness for loving wife