We claim the ornamental design for a lens for a head mount display, as shown and described.
FIG. 1 is a front perspective view of a head mount display according to the invention;
FIG. 2 is a front view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a bottom view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a rear view thereof; and,
FIG. 8 is a rear perspective view thereof.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines in the drawings form no part of the claimed design. Broken lines formed by equal length dashes show unclaimed subject matter. Broken lines formed of unequal length dashes (i.e., dash-dot) define bounds of the claimed design.