20 CFR 404.1583 - How we determine disability for blind persons who are age 55 or older.
(a) You are blind;
(b) You are age 55 or older; and
(c) You are unable to use the skills or abilities like the ones you used in any substantial gainful activity which you did regularly and for a substantial period of time. (However, you will not be paid any cash benefits for any month in which you are doing substantial gainful activity.)