Introduction to Vision Impairments

3.4. Assistive Technologies for Mobility and Orientation

In the previous section, we have seen that mobility and orientation are one of the main challenges that a person with vision impairment faces. To orient themselves to the environment and move safely, a person who is blind may pay attention to sensory inputs of smell, sound, air currents, surface texture etc. which alert them to pick up cues on the terrain and environment.

Persons with vision impairment may also choose to travel with the help of these aids: A sighted guide, dog guide, the cane, electronic aids or alternative mobility devices.   In this section, we discuss assistive technologies, which are the last three approaches in the list.

3.4.1. Walking Cane

The cane is the most common mobility aid for persons with visual impairments. It is designed to maximize the tactile and auditory input from the environment for the user to detect obstacles and landmarks. The standard cane consists of the grip, the shaft
and tip and it takes two to three months of training for a person with vision impairment to develop proficiency in using the cane for mobility.

Canes cost less and are simple to use. However, they have significant limitations such as:

(1) Obstacles outside the range of the cane are not detected and sometimes, it is difficult for the user to adjust or avoid an obstacle within the space of one step.  
(2) The cane only senses obstacles at a height below the waist level of the user. Head-height obstacles like tree branches are not sensed and knee-level obstacles like a table may be missed until the user runs into it because the cane may pass between the legs and under the top of the table.

The two-minute video below shows users with vision impairment explaining what the white cane means to them.