Blindness under a State plan.

We shall also consider you blind for the purposes of payment of supplemental security income benefits if— (a) You were found to be blind as defined under a State plan approved under title X or title XVI of the Social Security Act, as in effect for October 1972; (b) You received aid under the State plan because of your blindness for the month of December 1973; and (c) You continue to be blind as defined under the State plan.