What is visual impairment? Explained

This post provides a foundational understanding of persons with vision impairment in India. Also covered are the definition, forms, causes, severity, and prevalence of visual impairment.

At the end of this blog, the student will:
  • Acquire an adequate understanding of diverse definitions.
  • Recognize the causes of vision impairment
  • Acquire knowledge of the administration and function of a social worker 

Contents

  1. Introduction
  2. Definition
  3. Types of Visual Impairment
  4. Categories of Visual Impairmen
  5.  Prevalence of visual disability over years
  6. Degree of visual disability: 
  7. Causes 
  8. Management 

Introduction

While the eyes are certainly a key component of vision, they are only one aspect of a much larger and more intricate system. Visual information is taken in by the eyes, processed by the brain, and ultimately conveyed to the observer (Ward, 1996). There are many moving pieces involved in vision, but none more important than the brain in interpreting what we see. When this entire process breaks down and the brain is unable to synthesise what the eyes see, the result is visual impairment. Sometimes only part of your vision is affected, and that's something that might be helped by a technology, so it's not always a total loss. A person with such impaired vision is not considered blind.

The World Health Organization published a Fact Sheet on Visual Impairment in August 2014; it estimated that 285 million people were visually impaired, 39 million of them were blind and 246 with low vision. The terms "blind" and "poor vision" are sometimes used interchangeably, despite the fact that they describe fundamentally different visual impairments. Although it is encouraging to see a significant decline in the number of persons who have lost their sight due to infectious diseases in the previous 20 years, much more work has to be done. It's also worth noting that 80% of cases of visual impairment are preventable or treatable. (W.H.O, 2012)

People who are visually impaired are sometimes denied access to jobs and other opportunities. The majority of people don't take advantage of the employment chances that are available. To go about their everyday lives, obtain basic necessities like food, shelter, and medical care, they must rely on the kindness of others. As agents of social change, social workers have a responsibility to disseminate information about available services for people with disabilities so that they can participate fully in society.

Definition 

The Persons with Disabilities (Equal Opportunities, Protection of Rights and Full Participation) Act, 1995 and the National Programme for Control of Blindness (NPCB) in India define visual impairment as follows:

Visual acuity and field of vision determine blindness. The Persons with Disabilities Act, 1995 recognises low vision as a category of disability and defines it as follows: "Person with low vision" means a person with impaired visual functioning even after treatment or standard refractive correction who uses or is potentially capable of using vision for planning or executing a task with an appropriate assistive device.

The Ministry of Social Justice and Empowerment, India (2001) classified Low Vision as a person with vision impairment of less than 6/18 to 6/60 with best correction in the better eye or field impairment in any of the following categories:- Less-than-50-degree fields Hemianopia with macular involvement

National Sample Survey Organization's 58th round survey defined visual disability as the inability to perform tasks requiring appropriate visual acuity. For the poll, visually impaired comprised (a) those who had no light perception - both eyes taken together and (b) those who had light perception but could not count fingers of hand (with spectacles/contact lenses if they used them) from 3 metres (10 feet) in good day light with both eyes open. Night blindness wasn't a visual impairment.

W.H.O. defines blindness as inability to see. The WHO working definition of Low Vision (WHO, 1992) is: "A person with low vision has impaired visual functioning even after treatment, and/or standard refractive correction, and has a visual acuity of less than 6/18 to light perception or a visual field of less than 10 degrees from the point of fixation, but uses, or is potentially able to use, vision for planning and/or executing a task."

Significantly diminished eyesight, impaired visual performance, yet usable vision are stressed. If there's usable vision, training may be possible. This individual isn't blind.

Types of Visual Impairment

There are four levels of visual function, according to the International Classification of Diseases -10 (Update and Revision 2006): 
  • normal vision 
  • moderate visual impairment 
  • severe visual impairment 
  • Blindness.
The term "low vision" refers to a combination of moderate and severe visual impairment. Low vision and blindness together make up all visual impairment. (W.H.O 2012)

Categories of Visual Impairment

The International statistical classification of diseases, injuries, and causes of death, 10th revision (ICD-IO), says the following about visual impairment, low vision, and blindness: 
  • visual impairment includes both low vision and blindness; 
  • low vision is defined as visual acuity of less than 6/18, but equal to or better than 3/60, or a corresponding visual field loss to less than 20 degrees in the better eye with best possible correction (ICD-IO visual impairment categories 1 and 2); 
  • blindness is defined as visual acuity of less than 3/60, or a corresponding visual field loss to less than 10 degrees in the better eye with best possible correction.

 Prevalence of visual disability over years

Analyzing previous NSS surveys allows one to determine the prevalence of vision impairment in India. First, there was a slight decline in the prevalence of visually impaired people between 1981 and 1991. Following that, their proportion dramatically decreased in 2002. Compared to the urban sector, the percentage of visually impaired people has dramatically decreased in the rural sector.

NSSO (2002) defined visual disability as the loss or inability to perform tasks that call for acceptable visual acuity. The survey included visually impaired people.

Two groups were tested: 
  • (a) those who could not perceive light with both eyes together, and 
  • (b) those who could, but were unable to correctly count fingers of the hand from a distance of three metres (or ten feet), in bright daylight, with both eyes open.

Night blindness was not regarded as a form of visual impairment. A total of 45,571 rural and 24,731 urban households from 4,637 villages and 3,354 urban blocks across the nation were surveyed. In rural and urban India, respectively, there were 49,300 and 26,679 disabled people counted. According to survey estimates, there were 18.49 million disabled people in the nation during July to December 2002, making up around 1.8% of the estimated total population.

Degree of visual disability:

Out of all visually impaired individuals, more than 70% were blind (of which 35% had no perception of light and more than 35% had light perception but were unable to count fingers from a distance of 1 metre), and almost 30% had low vision (that is the persons who had light perception but could not count fingers from a distance of 3 meters). The overall percentages of blindness and low vision among visually impaired people remained mostly unchanged across industries and gender. When compared to their rural counterparts, a higher proportion of the 35 visually impaired people with light perception who lived in urban areas used spectacles.

Recent data have been used to assess the scope of vision impairment, blindness, and its causes globally and per WHO area. Estimates for nations without data were based on a recently created model. According to estimates, there are 285 million visually impaired persons worldwide, 39 million of whom are blind. Eighty-two percent of all blind people are beyond the age of fifty. Uncorrected refractive problems account for 43% of all cases of visual impairment, and cataracts account for 33% of cases of blindness (51 percent ). As much as 80% of the overall worldwide burden of visual impairment in 2010 can be attributed to avoidable causes.

Causes  

Even though surgical techniques have improved in many places over the last ten years, cataract (47.9%) is still the leading cause of blindness everywhere in the world, except in developed countries (W.H.O 2012). Other major causes of vision loss in 2002 were glaucoma (12.3%), age-related macular degeneration (AMD) (8.7%), corneal opacities (5.1%), diabetic retinopathy (4.8%), childhood blindness (3.9%), trachoma (3.6%), and Onchocerciasis (1%). (0.8 percent ). All of the above, except AMD, are causes of avoidable vision loss around the world. In the least developed countries, especially in Sub-Saharan Africa, avoidable blindness is mostly caused by cataracts (50%), glaucoma (15%), corneal opacities (10%), trachoma (6.8%), childhood blindness (5.3%), and Onchocerciasis (1%). (4 percent ).

The National Sample Survey in India shows that old age is the main reason why 27 percent of people in rural areas have trouble seeing. Whereas cataracts are the main reason why 27 percent of people in cities can't see. Nearly half of people who can't see well do so because of old age or cataracts. This is true in both rural and urban areas. In almost 25 percent of cases in rural areas and 27 percent of cases in cities, the survey could not find a clear reason.

The ICMR and NPCB-WHO have done two major surveys in India that give information about the causes and frequency of visual impairment in India. First, these surveys show that the number of blind people in India has gone up, from 1.38 percent in 1971 to 1.49 percent in 1986. Second, the number of people who are blind because of cataracts has gone from 55% in 1971 to 81% in 1986. The WHO-NPCB Survey shows that 81 percent of blindness in the country is caused by cataracts. At the time of the National Survey, most people who said they couldn't see because of old age might have lost their sight because of a cataract. Both the National Sample Survey and the WHO-NPCB say that cataracts are one of the main causes of vision loss. However, the results of these surveys show that there are a lot of differences when it comes to other causes.

The simplest classification of causes of visual impairment is: 
  • Ocular Diseases and Anomalies 
  • General and Systemic Diseases 
  • Injuries and Accidents
Ocular Diseases and Anomalies: There are different types under this -
  • Buphthalnos: It is infantile glaucoma, which is one of the rarest conditions in children. Since an infant's eye is flexible, when the pressure on the eyeball goes up, the eye gets bigger. Most of the time, it happens when tissues in the area of the anterior chamber don't grow as they should. It causes the eyes to water a lot, make them sensitive to light, and cloud the cornea. Refractive errors can happen when the shape of the eye changes.
  •  Albinism: This is a genetic condition in which hair, skin, and eyes don't get enough pigment. Only the eyes are affected by "ocular albinism." Up until adolescence, the amount of pigmentation may go up a little bit with age, which makes it easier to see.
  • . Retinitis Pigmentosa: A slow-growing disease of the retina that is passed down from parent to child. The disease affects the rod cells in the outer part of the retina. It can cause problems like night blindness, tunnel vision, and not being able to see in the dark.
  •  Retinoblastoma: This is a tumour of the retina that is cancerous. It usually only affects babies, is probably always present at birth, and can sometimes be passed down from parent to child. It usually affects both eyes, and both eyeballs may need to be taken out.
  •  Retrolental Fibroplasia: This happens to children who were born too early and were given a lot of oxygen. It happens when new blood vessels grow and more fibrous tissue grows in the retina. As a result, a membrane forms on the back of the eye's lens, which makes it hard to see.
  • Retinal Detachment: This is when the retina separates from the layer of pigment epithelium that covers it. From a medical point of view, there are two types: (1) secondary detachment, which has a clear mechanical cause and happens after other things in the eye. Simple detachment is caused when a hole forms in the retina. It comes from myopia that gets worse over time, diabetes, and diabetic retinopathy. It causes vision loss without pain, flashing lights, a smaller field of vision, and less clear vision. Most of the time, laser surgery and cryosurgery are used to treat it.
  • Diabetes Mellitus: This is a disease that runs in families and affects the retina. Diabetes-related retinopathy is another name for it. It causes vision to change, loss of colour vision or visual field, refractive error, and less clear vision.
  • Trachoma is a disease of the conjunctiva and cornea that lasts for a long time and spreads easily. It is caused by an organism called Chlamydia. The main infection affects the conjunctiva and hair follicles, and when it spreads to the cornea, ulcers form.
  • Glaucoma is caused by a blockage in the channels that let water out of the eye at the angle of the anterior chamber. It also causes the pressure inside the eye to rise, which is bad for the eye. It is usually passed down from parent to child.
  • Cataract: The word "cataract" comes from the Latin word for "waterfall." This is how the eye ooks when the lens gets cloudy and opaque. It means that the lens is no longer clear because the physiochemical processes inside the tissues have changed. It is usually linked to getting older. When a cataract is present at birth, it is called "congenital."
General and Systemic Diseases: The eyes are at risk for a number of general and systemic diseases that affect the circulatory and metabolic systems. The most common diseases that can cause vision loss are:
  • High blood pressure: Vascular retinopathy is linked to high blood pressure and a lot of damage to the blood vessels in the retina. Retinal edoema happens because of the changes in blood flow.
  • Vitamin A Deficiency: Vitamin A is important for the growth of the body's surface tissues, like the eye. Having too little vitamin A can cause damage to the cornea, ulcers, and even blindness, especially if you also have measles or aren't getting enough food.
  • Chronic diarrhoea: It can lead to blindness in rural areas. Most of the time, losing vitamin A makes the cornea soft, which can lead to Keratomalacia.
  • Eye problems and vision loss can be caused by multiple sclerosis, problems with the thyroid gland, certain vitamin deficiencies, and other diseases that affect the whole body.

Management 

Accidents and injuries: Many cases of vision loss in school-aged people are known to be caused by injuries, accidents, or poisonings. In fact, accidents and injuries are not a major cause of blindness because both eyes would have to be affected at the same time. The injuries are a major cause of monocular vision loss that can be prevented and treated.

If you are having trouble seeing, getting an eye exam as soon as possible is very important. Most cases of blindness can be avoided if vision problems are found and treated when they are young.

UNICEF has found a few signs that could mean a child has trouble seeing. Parents can check for these signs if they are worried about their child's eyesight. General signs that can show up right away:
  1. The child squints or blinks when looking at something. 
  2. The child’s eyes are crossed. 
  3. The child favours one eye more than the other when looking at an object. 
  4. One or both of the child’s eyes turn in or out. 
  5. The child’s pupils are hazy. 
  6. The child’s eyes are tearing excessively, are red, or the eye-lids are encrusted with matter. 
  7. The child turns or tilts his head abnormally

Visual Aids

People who can't see have a lot of options for helping them see. Here are a few of them: 
  • People who can't see have a lot of options for helping them see. Some of them are: Learning tools like abacus, arithmetic frames, geometry kits, etc. Giant Braille dots system for blind kids who learn slowly. Dictaphones and other ways to record at different speeds. Tape recorder for blind student after XII 
  • There are measuring tools like tape measures, micrometres, and talking scales and thermometers that can be used to learn about science. Blind students after the 12th grade can get Braille writing tools like Braillers, Braille shorthand machines, and typewriters. Geography learning tools like raised maps and globes and calculators that talk
  • Communication tools for people who are both deaf and blind. People who are both deaf and blind can use a phone with a Braille attachment.
  • Low-vision aids include hand-held stands, magnifiers with and without lights, speech synthesisers, and Braille computer attachments.
  • Special mobility aids for visually disabled people with muscular dystrophy or cerebral palsy like adapted walkers
There are many non-governmental organisations (NGOs) that help people with visual impairments live normal lives. The Sight First programme of the International Association of the Lions Club is the largest effort by the public to prevent and cure blindness and help people who are permanently blind or visually impaired (LIONS). This programme supports, among other things, the largest WHO-led effort to build eye care centres for children (45 national reference paediatric centres have been set up in 35 countries so far).

For a social worker who helps people who can't see, it's important to know that these people are not a burden on society. Social workers can work to raise awareness about how to prevent blindness, in early identification and intervention services, in the design and development of aids for the blind, in psycho-educational assessments, and in rehabilitation, which includes helping people learn to use their eyes.

Community-Based Rehabilitation (CBR) and a lot of other things. DuBois and Miley (2005) also say that, in line with the profession's goal of helping people, social workers' interventions are usually made to improve the way people work and to make society's structures better at giving people, including people with disabilities, the resources and opportunities they need. With the right help and training, these people can almost live a normal life.

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