Introduction to Visual Impairment

Introduction

Vision is the primary sense used for learning in the early years. Approximately 80 percent of what a child learns is learned visually. Early detection and treatment of vision disorders are important to maximize a child’s visual potential. The longer eye conditions are left untreated, the more likely they are to worsen, affecting learning ability, athletic performance, and self-esteem. Children under the age of six who do not receive proper and regular vision screenings and eye examinations are at risk of facing a lifetime of vision loss due to several common and correctable visual difficulties. 

How Do We See?
1. Our eyes do not see. Instead they are the medium through which we can see and look
2. Light passes into the eye through the pupil and forms an upside-down picture of what we look at on the retina (the lining at the back of your eyeball). 
3. The optic nerve sends messages to our brain about the picture. 
4. The brain then turns the picture the right way up again. 

Visual Impairment Characteristics

There are a number of characteristics associated with visual impairment. Some common visual impairment characteristics include:

1. Reduced visual acuity: The patient has difficulty seeing objects with near or close vision.
2. Blurred vision: Objects appear hazy or out of focus.
3. Tunnel vision: Limited ability to see things from the side, above, or below central vision.
4. Light sensitivity: Pain or discomfort when exposed to bright light.
5. Night blindness: Difficulty adjusting to low or dim light.

Signs of Visual Impairment

There is no single sign, but rather a combination of factors that indicate a person has a visual impairment. It can be any one or more of the following signs:

1. Bumping into objects
2. Moving hesitantly or hugging the walls
3. Touching or grabbing objects in an uncertain way
4. Squinting or tilting their head to see things
5. Having trouble distinguishing faces

Types of Visual Impairment

As per the Indian Act “Rights of Persons with Disabilities (RPWD) Act 2016”, visual impairment is officially classified into two main categories: 

Blindness and Low Vision. These categories are determined based on the Best Corrected Visual Acuity (BCVA) in the better eye or the limitation of the field of vision. 

Blindness 

According to the Act, “Blindness” refers to a condition where a person has any of the following, after best correction: 

1. Total absence of sight.
2. Visual acuity not exceeding [value] in the better eye with best possible correction. Here, visual acuity is the amount of vision or sharpness of vision/distance of vision.
3. Limitation of the field of vision subtending an angle of fewer than 10 degrees. The field of vision is the whole area seen when looking straight ahead without moving the head and eyes. 

Let us understand the terms used in the definition

A person is considered visually impaired only after vision is “best corrected”. If the person has a refractive error like myopia or hyperopia, the refractive error can be corrected. Myopia is known as nearsightedness. In this condition, it is difficult to see distant objects, but a person with myopia can work well with near tasks such as reading. Hyperopia is known as farsightedness. In this condition, nearby objects may appear blurry, but distant objects are clear. These refractive errors can be corrected, and then the vision is “best corrected”. If a visual condition can be corrected with surgery or any other treatment, it will not be considered as visual impairment.

Low Vision: 

Low vision is a term used to describe varying degrees of vision loss, but not total blindness. Low vision is caused by disease, trauma, or a congenital (genetic) disorder. 

Importance of Touch Sense for Persons with Visual Impairment

The sense of touch is vital for individuals with blindness in exploring objects in the environment, and reading Braille is a system of reading and writing with dots. The tactile receptors in the fingertips are receptive to tactile input. The high density of nerve endings on the fingertips allows  blind individuals to engage with the written word in a functional and empowering manner. Before we learn the concept of Braille, let us learn the importance of the tactile sense.

The sense of touch, or the tactual sense, is located in the skin. Some parts of the skin, which include tongue, lips, face, fingertips, and soles of the feet are more sensitive than others. For example, when something hot is eaten, the tongue gets burnt. For persons with visual impairment, touch remains a primary means of getting concrete and exact knowledge about the world around them.

The sense of touch plays an important role in the cognitive development of a visually impaired person. Through tactual exploration, a person gets an understanding about aspects like the shape, size, weight, hardness, softness, texture and temperature. It helps the person to identify objects and know their characteristic features. 

For example
i. Touching a chair and identifying its parts
ii. Touching a real ‘cat’ and feeling its shape, life, and motion 

The sense of touch helps in orientation and mobility, as it helps to identify physical landmarks such as trees, fences, and obstacles, and helps the person to navigate safely. Trailing an object (following an object using the back of the hand) enables the person to move. The person can also determine through her feet the kind of surface she is walking on-whether it is grassy, wet, sandy, concrete, or uneven. This helps her to understand  the kind of land, its geographical features, and climatic conditions. A well-developed sense of touch is also essential to independently carry out activities of daily living, such as eating, bathing, dressing and so on. 

Braille and its Importance

Braille was first developed around 1820 by a young Frenchman named Louis Braille. He produced Braille by modifying a system of night writing that was intended for use by nighttime artillery crews. He did this work at the age of eighteen. He and his friends at the school for the blind found that reading and writing with dots was much faster and easier than reading raised print letters. The development of this system by young Louis Braille is now recognized as the most important reading and writing medium for the visually impaired to obtain a good education.

Slate and Stylus 

The slate and stylus are tools used by visually impaired persons to write. They assist students with speedy writing, are easy to carry, and are a convenient mode for making Braille dots to write Braille characters.

The slate and stylus, like pens and pencils, are inexpensive writing tools. They are simple to use, easy to carry, and convenient for taking notes in classrooms. They are available in a variety of styles and sizes. A stylus has a metal point for punching the dot into the page, and a small handle that can be firmly and comfortably gripped by the index finger and thumb. Although the shape and size of the handle may vary, all styluses will have a metal point for embossing Braille dots. The typical slate is made either of metal or plastic. 

The Braille slate consists of arrangements of dots that create letters of the alphabet, numbers, and punctuation marks. The basic Braille symbol is called the Braille cell and consists of six dots arranged in the formation of a rectangle, three dots high and two across. All symbols, letters, and numbers consist of one or more of these six dots.       

Perkins Brailler

A Brailler, also called a mechanical braille writer, is a kind of braille typewriter. Paper is inserted in the machine. The raised braille dots that are made into the paper can be read with the fingers. 

The Perkins Brailler is the standard mechanical braille typewriter, invented in 1951. It features a 9-key layout that allows users to simultaneously press combinations of keys to emboss raised braille dots on paper. It is durable and it operates without electricity. 

The Perkins Brailler has been the most widely used mechanical braille writer in the world since its invention in 1951.

Use of Computer Keyboard for Braille Input

Using a standard computer keyboard for Braille input—often called six-key entry—replicates the typing method of a traditional Perkins Brailler. Users press multiple keys simultaneously to represent the dots of a standard 6-dot Braille cell.

Braille keyboards are especially useful for individuals who are familiar with braille characters and less familiar with the keys of a standard keyboard. There are only 8 keys that need to be memorized on a braille keyboard. Braille keyboards use the following six keys to type out braille characters: f, d and s correspond with braille dots 1, 2, and 3, and keys j, k, and l correspond with dots 4, 5, and 6.

Reading Software

JAWS (Job Access With Speech)
JAWS (Job Access With Speech) uses text-to-speech (TTS) voice synthesizers to read aloud on-screen information for blind and visually impaired users. It was developed by Ted Henter, who lost his sight in a car accident in 1978. He developed the software in the mid-1980s and later founded the Henter-Joyce Corporation, which merged with Freedom Scientific in 2000. JAWS was originally released in 1989 and has since become one of the most popular screen readers for blind users. It converts digital text into spoken words or outputs it to a refreshable Braille display.
JAWS (Job Access With Speech) converts a computer into a talking computer. It reads out all the content that is on the computer’s screen through the computer’s speakers/headphones, thus enabling a visually challenged person to use the computer independently and work on all MS Windows applications.

NVDA
NVDA (Non Visual Desktop Access) is a free, open-source screen reader for Windows that converts on-screen text into spoken audio using a built-in speech synthesizer or compatible third-party voice engines.
A voice synthesizer (or Text-to-Speech engine) in NVDA (NonVisual Desktop Access) is the component that converts text and on-screen elements into spoken audio. It acts as the “voice” of the screen reader, allowing blind or visually impaired users to hear what is happening on their Windows computers.
NVDA (Non-Visual Desktop Access) allows blind and visually impaired people to access and interact with the Windows operating system and many third-party applications.

MAGic
MAGic is an assistive technology software designed for individuals with visual impairments to independently use a computer. It acts as both a screen magnifier and a screen reader, enlarging digital content and reading it aloud.
MAGic is a screen magnification and screen reading solution for low vision computer users.

Relevance of Braille

Braille remains entirely relevant today as the ultimate foundation for true literacy, independence, and career success for blind and visually impaired individuals. Although assistive audio technologies like screen readers and speech synthesis have expanded rapidly, listening is not the same as reading. Audio alone fails to teach critical formatting, spelling, grammar, and structural language rules. Statistics consistently demonstrate that Braille literacy directly correlates with higher academic achievement and a significantly greater probability of gainful employment. Instead of making Braille obsolete, modern digital tools have integrated it to enhance access and accessibility globally. 

Video – How do we see

Video – Importance of Touch Sense

Worksheet – Introduction to Visual Impairment

Teacher Resource Document – Introduction to Visual Impairment