Visual impairment is classified as a type of impairment where the patient loses or has a decreased ability to see so much so that normal aids like glasses or lens are no longer helpful the person. There can be many causes to this such as disease, trauma, degenerative conditions etc. According to the American Medical Association, impairment is classifies as: the loss of one eye equals 25% visual impairment and a 24% impairment of the entire body; total blindness in both eyes is considered to be 100% visual impairment and 85% impairment of the body. In USA, visual impairment is further classified into:
- partially sighted
- Clear Presence of a visual problem.
- low vision
- Means severe visual impairment, and not just at mapping distances. Low vision includes all people who are unable to read the newspaper at a normal viewing distance, with or without eyeglasses or contact lenses.
- legally blind
- This means that a person has less than 20/200 vision even after the best correction (contact lenses or glasses)
- totally blind
- As the name suggests, this means no light is detected by the individual (Capi, 2012).
Assistive technology for Visually Impaired People
It is not impossible for people with serious visual impairments to live independently. Especially since the invert of modern technology and the tools that came with it. Examples of assistive technology for visually impairment include the Canadian currency tactile feature, which is almost like the Braille but not exactly. For normal computer use, technology such as reading screen displays has been widely taken up along with standalone reading aids that integrate a scanner, optical character recognition (OCR) and speech rendering all in one. All these function without the need of another PC (Guerrero et al, 2012).
Other examples of such assistive technology include:
- Screen magnifiers
- They help in enlarging texts so that it can be easier to read.
- Speech recognition software
- These allow users to operate PCs using their voice driven commands.
- Text-to-speech (TTS) software
- This converts a text file or text message or email to speech and reads them out loud so that those who cannot see can operate by hearing.
- Optical character recognition (OCR) software
- Large monitors
- Closed circuit television (CCTV)
- Hand held electronic magnifiers
- Dictation devices and transcription
- Standalone reading machines
- Fusers and swell paper
- Braille technology
- Refreshable braille displays
- Braille notetakers
- Braille embossers
- Braille writers
- Braille translation software
- Converts an input of braille characters into regular English language and vice versa.
- Alternative keyboards
- These keyboards are designed specifically for those who cannot see properly hence they will contain Morse code or braille characters instead of keys.
- Audio description
- Audio players
- Digital books
- These are normal books converted in digital format which can be read out loud by the system.
Navigation for Visually Impaired People
The biggest hurdle faced by visually impaired people is that of movement. With the vision compromised it is exceedingly difficult to continue. Fortunately there exists a community which aims to better the lives of these people and have introduced some amazing products. The days of walking with a stick or a watch dog are long gone now (da Silva Cascalheira et al, 2012).
Out Door Navigation
One of the modern tool in use for assisting the visually impaired is the Global Positioning System (GPS). Since its introduction in the late 1980s there have been many attempts to integrate it into a navigation-assistance system for blind and visually impaired people.
Most of the outdoor systems involve some sort of a wearable device, although lately they have shifted towards making apps on smartphones due to the fact that modern day smart phones are extremely powerful and most of them include a stock GPS. Also due to the powerful APIs and platforms such as iOS, Windows Mobile, Android, Symbian OS etc available it is easier for the user and the manufacturer to make affordable and practical devices (Spinks, 2014).
As far as the stand alone devices are concerned, most of them are PDAs,
This is a relatively new field but it is generating a lot of interest as tech companies are entering into research and developing new ideas and devices with help blind people ‘see’ and movie around their very own homes. Most of the technology is still research with many research papers being patented by top companies in the Silicon Valley. Most of the concepts surround the idea of giving the user a sense of surrounding by either saying it or by vibrating motions sensors. Some ideas also included a sonar type ultrasound mapping device that gives the user a feel of the obvious. (Hunaiti &Balachandran, 2006).
Interface for navigation applications
For an Assistive device it is important that is gives as much convenience to the user as possible. Because not only is the user under a lot of challenge already, a bad interface will compound the problem.
Modern day smartphones have been of tremendous help to the visually impaired because they allow manufacturers to put so many features in that before required at least 2 or 3 separate gadgets. Also as GPS is a common feature among the smart phones, it has further helped in keeping things simple for the user.
- Loadstone GPS
- This is an open source software for GPS navigation for blind and visually impaired users. The software is free to download and edit and currently is on the Symbian OS, which is supported by all Nokia cell phones. As a prerequisite, a GPS receiver must be connected to the cell phone via Bluetooth or any sort of connection.
- This is a project by Fachhochschule Hannover. This is similar to the Loadstone as the user is led by direction and distance information. The text on the screen is read out by a screenreader. An additional feature is that a Vibration-Only navigation is possible. All the map data for any city can be retrieved from the OpenStreetMap database.
- Mobile Geo
- This is a Windows mobile app by Code Factory. Specifically designed for Windows smartphones, small PCs and PDAs. This mostly supports mapping technology from the some leading providers of GPS technology to the visually impaired. Mobile Geo was the first, one of a kind solution that is specifically designed to serve as a navigation aid for people with a visual impairment which works with a wide range of mainstream mobile devices.
- Now in the Apple devices we have BlindSquare is MIPsoft. Its unique feature is that it uses crowd sourced data. It uses Foursquare for points of interest and OpenStreetMap for street info.
These have been out of fashion as of late but they have found a new found use in the new research conducted into especially when assisting the blind particularly to help them in their homes (Al-Shehabi et al, 2014). Following are some of the technologies incorporated in this sector:
- The Victor Trekker, is designed and manufactured by HumanWare. It is a personal digital assistant (PDA) application operating on a Pocket PC, optimized for the blind and visually impaired with many features such as talking menus, talking maps, and audio GPS information. It is fully portable, and it offers features that enable a blind person to determine position, create their own routes and receive audio information on navigating to a preset destination. Another feature is that it also provided search functions for an exhaustive database of point of interests, such as restaurants, hotels, etc.
- BrailleNote GPS
- This is being developed by Sendero Group, LLC, and HumanWare. This device acts as a combination of a PDA, and interactive interface. Using a very small receiver that is the size of a cell phone, the BrailleNoteuses GPS to pinpoint a traveler’s position on earth and nearby points of interest e.g. restaurants, libraries etc. Using the voice synthesizer, The BrailleNote communicates the directions and coordinated of any set destination to the user. The system also uses multiple satellites and cell towers to triangulate the user’s position, just like a ship lost at sea.
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