"The nature or degree of certain disabilities might render them
non-evident to others. Chronic fatigue syndrome and back pain, for example, are not apparent conditions. Other disabilities might remain hidden because they are episodic. Epilepsy is one example. Similarly, environmental sensitivities can flare up from one day to the next, resulting in significant impairment to a person's health and capacity to function, while at other times, this disability may be entirely non-evident. Other examples might include:
Other disabilities may become apparent based on the nature of the interaction, such as when there is a need for oral communication with an individual who is deaf, or there is a need for written communication with an individual who has a learning disability. A disability might become apparent over time through extended interaction. It might only become known when a disability accommodation is requested or, simply, the disability might remain
non-evident because the individual chooses not to divulge it for personal reasons."
Ontario Human Rights Commission, Policy and Guidelines on Disability and the Duty to Accommodate, revised November 23, 2000. [Online] Available: http://www.ohrc.on.ca, 10.