Impairment is the loss of a function of the body
For example, when someone has difficulty seeing. Impairments are mostly irreversible and lifelong.
Sometimes the impairment can be treated, for example in the case of vision by using spectacles as prescribed by an optician.
Impairment is not a problem in itself. But it is the barriers in society which restrict the participation of a person with an impairment that make it problematic.
Impairment x Barrier = Disability
Disability is when the person has an impairment and experiences a barrier that prevents them from performing or participating in an activity
For example; if someone cannot see at all, and therefore cannot read printed materials. If the materials were in braille, there would be no barrier for the person to read.
Impairment is not a problem in itself. But it is the barriers in society which restrict the participation of a person with an impairment that make it problematic.
In the United Nations Convention on the Rights of Persons with Disabilities (UNCRPD), the following definition is given for persons with disabilities: