Electronics and visual impairment

Since 1970-1980 some health workers have envisaged people, considered so far as totally blind, with their visual abilities left. Now, visual impairment is a full concept. In France, the reference to determine a visual impairment is the World Health Organization 's definition : the score of keenness of far vision got by the best eye, with optical correction equipment, must be included between 1/20 and 4/10, according to the level of damage of visual field. International handicap classification allows to take account of
disabilities due to this state.

At the same time, during these ten last years, the computing French market changed dramatically. Growth of Internet, from which new kinds of information are developed as e-market and supplier-custom chains, can be
studied also with individuals : in 1998, there were 1 500 000 regular Internet surfers, including 50% subscribers to an on-line service. 810 000 people used Internet only at home, 510 000 only at work, and 200000 both at home and at work.

In such a context, it would be a pity not to seek and develop practical appliances from means offered by electronics to answer visually impaired people's needs. In France, using computerised tools by visually impaired people is a reality and answers to government's politics for disabled people's integration. Available equipments displayed by the market, including e-books, meet a part of the needs. But visual impairment' specificities must guide ergonomic developments of these tools to facilitate their use.

1. Market does exist :

   Whereas epidemic studies still lack in our country, it is well known that about 1,5 million people, including almost 2/3 over 65, are concerned. This number doesn't stop growing because of the increase in life expectancy, the evolution of demography, and also because of emergency care' medical progress.
   Since the Law (June 30th, 1975) in favour of the disabled people, specific measures have been set to promote social integration :

   • The Law, July 10th, 1987 forces the whole public corporations employing more than 20 people to reach, after three years, a quota of 6% disabled workers,
     

   • The Law, July 10th, 1989, promotes young disabled people's school integration,
     

   • In the set of politics defined by the Prime Minister on the 25th of January, and in extension with the works about autonomic life' local sites, the government wishes to develop accessibility to human
     facilities, which allows disabled people to get a free choice of way of life.

     Therefore, in order to optimise integration' success, everyone must be able to access to information and education, according to one' s handicap and ability.

2. Population is varied :

   There are about sixty definitions of visual impairment around the world, but no one takes functional sight into account, which is defined as the whole sensorial abilities practically used, a wider definition than the
   lonely visual keenness determination.

   The visually impaired person doesn't belong to blindness' world, he doesn't get the same difficulties.

   Visual impairment is not a disease but the result of varied pathologies which affect visual system.

   • In its causes and its expression, one must make a difference between congenital visual impairment, and brought visual impairment which occurs to someone who had, more or less long sight experience. This one, who has been able to get visual intact and/or amputated information, and to structure images and visual representation, will keep memory of the ability to use these mental representation, when becoming visually impaired.

   • One must precise that the time when the handicap occurs is important :
     

     • A visually impaired adult may have been a visually impaired child ; he will then have structured one's knowledge according to one's visually childishly handicap and to one's previous daily living experiences.
       Therefore, he will get a more or less important visual patrimony, compensatory strategies more or less adapted to circumstances, and the earlier a new technology will be fixed, the better he will adapt himself.
       

     • An adult may become visually impaired in an elderly age and, besides a longer time for adapting himself to use a new tool, he may get associated troubles as "prebyacousy", Alzheimer, arkinson. which may influence spatial perception, gestural preciseness or mechanisms of memorization and superior functions. These elements must be studied when choosing the use of a particular technology.
       

       • In a same way, this will be the kind of visual pathology, according to a central origin or trauma or retinal one, which will guide the choice and ability to use an electronic equipment.
         

       • In case of retinal affection, the disease' localization doesn't not require
         the same information' strategies and defines some of functional vision'
         features for a particular use of a same equipment.
         We can distinguish :

       
       

     • Central retinal affections, as Stargardt disease, the "dégénérescence maculaire liée à l'âge" (DMLA). These affections hit the .. Retinal Zone which allows, when it's healthy, precise details' discrimination, colours and right in front fixation' perception. These lesions may be absolute and no more allow any perception in the space corresponding to this zone ; or they may be partial and allow one or several damaged levels of perception, and allow sometimes to fix right in front some things or visual scenes according to their physical content (wavelength, level of contrast, brightness, size). These lesions may have variable localization and surface. So, they may extend on a particular retinal zone (temporal, nasal, upper or lower), to more than 25° of the macular zone, and they may sometimes preserve a para or juxta foveolar zone.

     • Peripheral retinal lesions, as pigmentary retinopathy, hit the retinal periphery which, when it's healthy, allows moves' perception. These lesions are more or less important, and occur a tubular vision. Central keenness of vision is still kept for a long time and may reach 10/10 whereas visual field may be reduced to a few degrees.

     • Mixed lesions, as diabetic or myopic retinopathies and glaucoma, show
       both central and peripheral lesion.

     
     

     The kind of pathology responsible of visual impairment and its stage of evolution with its physiologic features, the available visual functional abilities, the way the pathology progresses, the needs and motives will determine the strategies to develop, the activities to increase and the means to implement. For example, it will be possible to use e-books.

   
   

3. Symptoms are varied :

   Perceptive phenomena are not permanent and depend as well of pathology, general state, sensitive balance and raised interests, as of ergonomic and luminousness of environment, physical content and multiplicity of information.

   The daily subjective discomfort may be progressive or brutal, remain for a while moderate or not. First, patients will often complain about insufficient light or the need to modify their optical equipment.

   As shown by studying several kinds of pathology, keen discrimination (determined by keenness of vision) is sometimes preserved, but one can note multiple functional anomalies as reduced reading speed, more or less alteration of mesopic vision, speed of recovery after macula dazzling, alteration of luminous contrasts' vision, dyschromatopsy, feelings of intermittent scotoma and metamorphopsies (apparition of distorted lines).

4. Patients' s expectations :

   • Near vision : reading, recognising faces, watching TV, writing
     

   • Intermediary vision : daily life activities, cooking, shopping

   • Motions : guiding oneself in town, crossing the streets, getting
     public transportations, riding a car.

   It is important to well define people' s objects and to consider their motives.

   Therefore, the one who has never been a great reader before one's visual impairment, will not become a satisfied low vision reader, even with an adapted device. For him, the best will be to involve himself into some leisure activity as fishing, playing cards, painting .

   About reading, one will consider the patient' s interests, as daily news' reading, specialised magazines, periodicals, mail, . One can see already the interest of using e-book in term of visual comfort, with the
   possibility to chose the characteristic of graphic signs, and accessibility to newspapers or books.

5. Different steps of the visually impaired person's care :

   When visual impairment is coupled to uncomfortable inabilities for daily life, it is important to evaluate ones visual functional abilities through :

   • namnesis of the general state, including current care and previous ophthalmologic therapies
     

   • multisensorial approach aiming at evaluate different senses and their balance
     

   • ophthalmologic examination with a diagnostic purpose, allowing to judge the evolution of pathology, for check degree of stability needed to develop later strategies. This examination allows too do define the best optical correction, for a far or near vision as much for an intermediary one.
     

   • a test of visual field to determine, for both eyes and binocular, functional zones of the retina, their localization, their size and level of perception..
     

   • a study of the vision of contrasts in variable luminousness which allows to determine the available "envelop" of the vision (ability to perceive), left eye, right eye, left and right eye, according to luminousness of the test and offered stimuli (optotypes, networks), of their spatial frequency and level of contrast.
     

   • a test of vision of colours
     

   • an orthoptical examination to evaluate statics (stability of fixation, strategy of excentration) and ocular dynamics (pursuits and jerks, strategy of visual scanning).
     

   • an optical examination to determine if possible magnifying optical
     devices would improve functional keenness of vision at the three distances.
     

   • an objective evaluation of functional vision including vision of forms and recognizing of things and visual complex scenes, understanding of precise move, test of need of magnifying referred to graphic signs "Parinaud 2" (same as in "Le Monde"), tests allowing to evaluate efficient reading (speed, understanding, marking in a text).
     

   • a subjective evaluation of functional vision which, through a semi conducted interview, allows to point needs and troubles of the daily life's person.
     

   • a psychological approach to aiming to estimate the abilities of adaptation and motives' s person.

   This evaluation may be completed by an ergotherapic evaluation oriented to daily life activities, and/or a psychomotor specific evaluation of sense of direction and mobility.

   Then, after discussion, members of the multi-disciplinary team may, or not, offer a rehabilitation protocol to the patient, which will aim to answer patient' s expectations thanks to a balance between tasks to do and available means. The tasks get a physical and cognitive content defined for every new activity. Means are perceptive, sensorial, motor, and cognitive.
   
   One will note that, in some cases, rehabilitation is not needed (for light visual impairment, most of the time). The means (strategies) used by the person are efficient enough to invest objectives by using a magnifying optical system, and/or using a tool as, for instance, an e-book which help to get a perception when reading.

   
   

6. Expectations facing computerised tool :

   Following what we said,
   Offered tools must answer the persons' s needs first : if they get uncomfortable reading, or if they are visually impaired with functional visual, motive and cognitive abilities allowing to read, without or after a
   rehabilitation. The information' content must answer the need (fall short of patient' s expectations) and be accessible. The equipment must be accessible. It must be easily handled (size of the screen, weight of the machine), used (attitude in an optimum comfort), switched on and adjusted (place and size of buttons), and programs must allow a short learning time and a satisfying use.

   Interface and menu must offer :

   • markings to optimise access to information
     

   • guides to allow to get easily information, by showing and guiding its site at the beginning of the search or after an interruption. Understanding of images, columns and paragraphs must be easy.

     Computerised tools allow to control :
     

   • the size of graphic signs and objects
     

   • the contrast (positive and negative) and level of luminousness and colour
     

   • the forms (types of graphic, space, interlines). For equal signs (courier) or non equal signs (Arial) there is a few difference of readability.
     

   • temporal unfolding of visual objects
     

   • complex computerised information as distinction between form and substance, relationship with the frames, and reinforcement of local contrasts.

   The ideal would be to increase contrast with regard of substance in a selective way (example : this head and these shoulders belong to the same object).

7. Conclusion :

   It is not enough to answer the visual impairment' s needs by increased graphic signs' size. Current knowledge of visual perceptive phenomena allows to refine an approach of functional abilities and promote the development of adapted devices. These ones must not be too different from the primary form of the product available to the general public, so as to respect social integration. In France, access to literacy is the first request of any kind of visually impaired people. Adapted and progressive interface, connected to a website and a database of books, periodicals and newspapers, should meet an interest among visually impaired people. We still expect developments of electronic devices by TV camera and virtual screen, electronic stick, or satellite assisted guiding which will promote far visual perception and move