Can. 930

§1. If an infirm or elderly priest is unable to stand, he can celebrate the eucharistic sacrifice while seated, but not before the people except with the permission of the local ordinary; the liturgical laws are to be observed.

§2. A blind or otherwise infirm priest licitly celebrates the eucharistic sacrifice by using any approved text of the Mass with the assistance, if needed, of another priest, deacon, or even a properly instructed lay person.