Assistive Technology

Assistive Technology (AT) for Blindness & Low Vision

We review Assistive Technology for Vision in the aspects of reading and writing 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.

In every section 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.


Visual Substitution

Visual Substitution is a special case of Sensory Substitution which changes the characteristics of one sensory modality into stimuli of another sensory modality.

A sensory substitution system consists of three parts:

  • A sensor,

  • A coupling system, and

  • A stimulator.

The sensor records stimuli and gives them to a coupling system which interprets these signals and transmits them to a stimulator.

In case the sensor obtains signals of a kind not originally available to the bearer it is a case of sensory augmentation.

Sensory substitution concerns human perception and the plasticity of the human brain; and therefore, allows us to study these aspects of neuroscience more through neuroimaging.

Sensory substitution systems may help people by restoring their ability to perceive certain defective sensory modality by using sensory information from a functioning sensory modality.


About Assistive Technology

Vision plays an important role in human development because it stimulates and directs human movements and actions. It is the agent's motivation to trigger the acquisition of skills, and it allows capture of the environment quickly and efficiently. Vision is the sense that rapidly unifies sensations (tactile and auditory) and sets a direction in relation to the other part.

The relationship with the outside world is accomplished primarily through vision; therefore, ocular problems can cause serious adverse effects on learning and socialization.

Low vision is characterized by a significant change in the functional capacity of vision that results in isolation and is caused by a single or multiple factors such as significant visual impairment, a significant decrease in the visual field, and changes in color vision and/or contrast sensitivity that interfere with or limit visual performance. It also can be described as any degree of visual impairment that causes disability and a decrease in visual performance.

While performing activities of daily living, there is a need to utilize reading and writing; these activities can be greatly affected by visual loss because the eyes are necessary to perform these.

Improvement in the visual performance of an individual with low vision can be achieved through the use of resources such as assistive technology. Assistive technology is an interdisciplinary area of knowledge that includes products, resources, methodologies, strategies, practices, and services that work to promote the functionality related to the activity and participation of individuals with disabilities, inabilities, or decreased mobility, and it can help those that are seeking autonomy, independence, quality of life, and social inclusion.

Assistive Technology helps people with blindness or visual impairment to partially make up for their lack of vision 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.

Assistive technology resources may be optical, non-optical, or electronic. These resources can lead to a decrease in functional losses in patients with low vision.

Optical aids include one or more lenses that are placed between the eyes and the object to promote the magnification or enlargement of the retinal image. The optical aids can be as simple as a glass lens to better see the details of a figure or as complex as a sophisticated telescope that can be used for far and near vision.

Non-optical aids are simple features that can increase visual resolution. These features do not involve the use of a magnifying lens to improve visual function, but they can be used in addition to optical devices or may possibly replace them in some instances. Some examples include filter lenses, lighting, marker pens, magnification of materials, and changes in contrast (dark background and light object).

While optical and non-optical aids have been around for centuries, over the last couple of decades electronic aids have made significant inroads in AT for Vision. We now have smart glasses replacing glasses, smart magnifiers replacing lens, dynamically resizable texts, read-out-loud, automated transcription and translation, and so on.

And electronic aids are getting more and more empowered with the use of AI. That is the future for AT.


Comparison of some common Assistive Technology for Blindness

Leading Research Groups in Assistive Technology in India

In India, several research groups and start-ups are creating cost effective efficient and smart solutions for blindness and low vision as well as other disability:

Research Labs