Sch 1 para 5
(1) An impairment is to be treated as having a substantial adverse effect on the ability of the person concerned to carry out normal day-to-day activities if— (a) measures are being taken to treat or correct it, and (b) but for that, it would be likely to have that effect. (2) “ Measures ” includes, in particular, medical treatment and the use of a prosthesis or other aid. (3) Sub-paragraph (1) does not apply— (a) in relation to the impairment of a person's sight, to the extent that the impairment is, in the person's case, correctable by spectacles or contact lenses or in such other ways as may be prescribed; (b) in relation to such other impairments as may be prescribed, in such circumstances as are prescribed.