The ornamental design for a contactlens, as shown and described.
FIG. 1 is a front planar view of a contact lens showing my new design;
FIG. 2 is a left side view of the contact lens; and,
FIG. 3 is a right side view of the contact lens.
The broken lines shown in the drawings are included for the purpose of illustrating unclaimed portions of the contact lens and form no part of the claimed design.