There are talking calculators, touch-typing softwares, specialist keyboards, cup-level indicators, sensory toys and many more such items that help visually-impaired people live a fuller life. There are various degrees of visual impairment and the society needs to be more sensitive in acknowledging and meeting the needs of these special people. As a consumer segment, the differently-abled are just as important a customer base.
Consumer VOICE has introduced a special column on identifying how the differently-abled consumers can be served better. Disability comes with a heavy price tag. Despite what government regulations may provide, it means fewer job opportunities, lower pay, and lower life fulfillment. From society it implies stigmatization and inability of people to get beyond what is perceived as an overarching problem. While some of the disabled in India have been able to excel in one field or another, there are many who live isolated lives with little more to look forward to than the bare necessities. Many of the challenges of the differently-abled (an alternative phrase for disabled) can be overcome with innovations in design, combining sensitivity to their needs with technology that is no longer rocket science.
Definitions of some visual capabilities
Visual acuity is the ability to see detail (small characters or features) that is presented to the eye. This can be measured for distant objects at 6 metres or at near at 40 cm by reading a chart of characters that becomes progressively smaller. A person with 6/12 visual acuity can see at a distance of 6 metres the level of detail that the normal person can see at 12 metres. Thus 6/6 is considered normal visual acuity and 6/12 characters appear twice as large as 6/6 characters in terms of angle subtended at the eye. Visual field is the capacity to see a large region of space simultaneously. For instance, a tiger has a smaller visual field than a lizard because of the lateral placement of the eyes in the case of the lizard which allow vision even behind the head. The visual field of a human is approximately 180 degrees while that of a lizard is close to 270 degrees. Visual field can be measured of one eye alone (monocular visual field) as well as of the two eyes together (binocular or bilateral visual field). While macular degeneration impairs central vision, glaucoma impairs peripheral vision. The ability to see detaildeclines from central to peripheral vision because of retinal cell structure and function. Contrast sensitivity is the ability to see patterns of different levels of contrast for example light gray patches on a white background make low contrast. Cataract reduces contrast sensitivity. Colour contrast is yet another property of the visual system, for example blue on yellow makes high colour contrast. Glaucoma reduces colour contrast.
Definitions of visual impairment
Visual impairment is vision loss that constitutes a significant limitation of visual capability resulting from disease or trauma or from a congenital or degenerative condition. This vision loss cannot be corrected by conventional means, including refractive correction, medication, or surgery. In more specific terms visual impairment is defined as
best corrected visual acuity in the better eye to be less than 6/18, or significant central field defect,
significant peripheral field defect including bilateral significant visual field defects or generalized constriction of field, or
reduced peak contrast sensitivity.
The terms partially sighted, low vision, legally blind and totally blind are used to describe children and adults with increasing degrees of visual impairment.
Statistics of visual impairment
Over 40 million people in the world are blind, and over 120 million people have significant low vision conditions that cannot be corrected, cured or treated by conventional refraction, medicine or surgery. This number is expected to double by the year 2020 (World Health Organization, 2004). Over 90% of these visually-impaired people live in developing countries like India. According to best available estimates, less than 15% of these visually impaired people in developing countries like India have access to vision enhancement or vision rehabilitation services that could help to change their lives. There are over 1.4 million visually impaired children aged 0-14 years.
General design principles based on visual acuity and contrast sensitivity
If a person has 6/24 visual acuity, her visual resolution is 4 times worse than that of a person with6/6 (normal) visual acuity. Thismeans that the size of charactersand lines must be 4 times largerand with high contrast for it to bevisible to the person with thatdegree of visual impairment. Inrelation to contrast, it helps tounderstand that the luminanceratio (intensity of light emanatingfrom the bright region divided bylight emanating from the darkregion) of the average newspaperprint varies from 5 to 7 eitherbecause the ink is not darkenough, or because the page is notwhite enough. If this contrast wereincreased to 15, as in some magazineprint, some people with visualimpairment would be able to readthe print if the size of the font werethe same or somewhat larger orwith a magnifying lens.
Over 40 million people in the world are blind, and over 120 million people have significant low vision conditions that cannot be corrected, cured or treated by conventional refraction, medicine or surgery. This number is expected to double by the year 2020 (World Health Organization, 2004). Over 90% of these visually impaired people live in developing countries like India
Design of indoor spaces for the visually-impaired
It is evident from a cursory analysis—and backed by solid science— that the visual system requires patterns that change in space or time in order to see anything at all. The open daylight sky is pattern-less without clouds and provides no clues to depth and therefore the focusing mechanism of the eye becomes disabled in such uniform field conditions. Imagine how difficult it would be to walk down a staircase made of pattern- less glass with polished edges. This is the challenge faced by the visually impaired when they walk in a hallway that has no visually resolvable pattern on the ground and no guide railing on the wall. Another example is the door handle that comes with a sign that reads “push” or “pull”. This is very ill-conceived design. To simplify the design, it would be wise to remove the handle where the door needs to be pushed and replace it with a flat plate that contrasts in luminance from the background of the material of the door.
Design of accessories for the visually impaired
Clocks, calculators and other accessories for the visually impaired are available from the Lighthouse for the Blind in New York City (www.lighthouse.org). There are large print books, Braille books and related educational materials for the visually impairedbut these are of a limited reader interest. Clearly our schools an educational materials are severely lacking in providing inclusive education for the visually impaired. However, with the new wave of electronic books, this scenario is about to change.
Design of assistive technology for the blind
In addition to canes and seeing eye-dogs, there are talking cellphones for the blind and voice-readout computer software for the blind to read web pages and email, and text documents in general. In Northern Europe where the problem of macular degeneration is most prevalent, there are handheld devices that communicate by wireless signals to enable blind people to cross the street at a zebra crossing or call out the name of the roads at a street corner. It is standard practice in many parts of the developed world for elevators in tall buildings to call out the floor name every time the door opens and yet I do not see this in the best buildings of Gurgaon—the IT capital of Haryana.
Cadres of personnel working in the interest of the visually impaired
Vision-Aid (www.vision-aid.org) is a not-for-profit organization based in the US providing low vision aid services in India in places like Vizag. Such low vision aid services are generally provided by optometrists and comprise magnifiers for reading, CCD cameras for projection onto a display terminal, and telescopes for distance viewing. While optometrists can generally effectively cater to those with low vision, they rarely if ever assist the legally blind or the totally blind. For such people there are visual rehabilitation specialists in the developing world such as at DrShroff’s Charity Eye Hospital in Daryaganj, New Delhi, and at several major eye hospitals in the country such as L. V. Prasad Eye Institute in Hyderabad, the Sankara Nethralaya in Chennai, and Aravind Eye Hospital in Madurai. In the developed world, clinician eye doctors collaborate with vision scientists to provide innovative but sometimes expensive surgical or computational options for retinal degenerations such as retinitis pigmentosa. There are hardly any ophthalmologists who specialise in low vision, and they practice in the most affluent parts of the world such as the west coast of the US. Generally low vision services are time consuming and the patients may be from a lower income group, thus optometrists are the personnel of interest for low vision in India. Maharashtra leads the way with 12 centres for low vision, Gujarat is a distant second with 5, and Tamil Nadu is third with 3 such centres.
Visual impairment in relation to the whole person
The American Medical Association’s Guides to the Evaluation of Permanent Impairment attempts to provide a standardised, objective approach to evaluating medical impairments. There are criteria for evaluating permanent impairment of the visual system as it affects an individual’s ability to perform activities of daily living. The Guide has estimated that the loss of one eye equals 25% impairment of the visual system and 24% impairment of the whole person; total loss of vision in both eyes is considered to be 100% visual impairment and 85% impairment of the whole person.
Conclusion
While the estimates above of 85% impairment of the whole person may be true for a situation in which the visual environment is ergonomically ill-suited for a visually impaired person, imagine how productive, effective and happy an intelligent person with visual impairment would be if architectural and aesthetic design principles were used in their interest and in the interest of the sighted majority. The sighted majority can easily adapt to the minor adjustments that will assist the visually impaired to be effective. I personally know and cherish the friendship of three people who are blind by legal standards and all three have successful careers on account of their indomitable will, family support and assistive technology (see www.silver-linings.org ).
Dr. Karan R. Aggarwala, Ph.D.
kaggarwala@gmail.com