Electronic Reading Devices for Low Vision

Close circuit televisions for the independance of persons with important vision loss

Federico Bartolomei

Close circuit televisions (CCTV) have an important role to play in the independance of persons who have lost major visual acuity. Technically, these are systems composed of a tele-camera which sends a signal directly to a monitor. The image received is then electronically reconfigured with parameters relating to size and contrast. Thanks to modern technology, there are on the market many different systems varying in structure (fixed systems, portable systems interfacing with the television or with the computer monitor, headgear device, or mounted on glasses), and technical characteristics (colour images, black or white setting, autofocus, or vocal command).
The use of the video magnifyer as a device for persons with low vision dates back to 1960. Initially, its use was limited because of  the theory based on the principle that sight had to be preserved, therefore restricting reading and writing activities. Latest scientific studies relating to cerebral plasticity and learning processes have demonstrated on the contrary that it is possible to rehabilitate a person with low vision optimazing the use of residual sight thanks to visual stimulation and exercises.
Not everyone with low vision finds the CCTV useful as it depends on the individual's ocular disease, which may not correspond to its use. Or, as often occurs, there is a lack of knowledge of the system and its proper use, or a lack of a personalized rehabilitation program based on the exact needs of the person with a visual impairment and his or her potential.
The choice of the CCTV must also be based on the patient's age and general abilities, which can have an influence on how the system is handled and what its proper use should be. Based on tests taking place in a specialized centre, the rehabiliation counsellor will guide towards the choice of simple and easy to use devices, rather than highly technical equipment capable of providing a multitude of functions, but which may be more difficult to manage.
The youth and teenager would make use of the system mainly for studies (reading and writing); the activities of adults will relate to office work; while seniors will generally use the system for their leisure activities (newspaper reading, card playing, etc.) and for the every day activities (reading mail, writing grocery lists, taking medicine, and so on).
Video magnifiers offer many advantages in comparison with optical systems with high magnifying capabilities. The distance for reading is comfortable, and the systems allow a better depth in focus and a wider visual scope compared to hypercorrective and telescopic systems. The reader may sit upright reducing the discomfort associated with bad posture. The user has maximum freedom, and is not restricted in his movements by the limiting distances of the magnifying optic systems, allowing simultaneous activities. The magnifying capabilities on the screen can be easily and quickly modified since different tasks require different levels of magnification. For example, reading the newspaper requires various levels of magnification, first to have a global view of the full page, then to have a specific view of an article of interest. Visual comfort also varies according to the size of the monitor and its technical characteristics and all that needs to be taken into consideration when the choice of a system is being made. Modifying the image's polarity, which means, for example, to visualize white letters on a black background, will reduce the annoying effect of brightness, which is a cause of such disturbance for persons with low vision. The Technical Aid Centre at the Institute for the blind F. Cavazza was created to study rehabilitation solutions, which are most adequate and which will satisfy the requirements of the low vision person. Solutions stem from a personalized rehabilitation plan taking into account the user's requirements and expectations, unlike information solely taken from an evaluation of visual functions.