John 9:5

When I am in the world

(οταν εν τω κοσμω ω). Indefinite relative clause with οταν and present active subjunctive ω, "whenever I am in the world." The Latin Vulgate renders here οταν by quamdiu so long as or while as if it were εως. But clearly Jesus here refers to the historic Incarnation (John 17:11) and to any previous visitations in the time of the patriarchs, prophets, etc. Jesus as God's Son is always the Light of the World (John 1:4; John 1:10; John 8:12), but here the reference is limited to his manifestation "in the world."I am the light of the world

(φως ειμ του κοσμου). The absence of the definite article (το φως in John 8:12) is to be noted (Westcott). Literally, "I am light to the world, whenever I am in the world." "The display of the character varies with the occasion" (Westcott).