The ornamental design for a lighttherapydevice, as shown and described.
FIG. 1 is an isometric top view of the light therapy device in accordance with the new design;
FIG. 2 is a top view thereof;
FIG. 3 is a bottom view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a front view thereof, with the nose bracket in an extended position (the nose bracket extended position is shown for illustrative purposes and is not part of the claimed design);
FIG. 6 is a rear view thereof;
FIG. 7 is a right view thereof;
FIG. 8 is a right view thereof, with the nose bracket in an extended position (the nose bracket extended position is shown for illustrative purposes and is not part of the claimed design); and,
FIG. 9 is a left view thereof.
The broken lines showing the extended position of the nose bracket in FIGS. 5 and 8 are included for the purpose of illustrating environmental structure and form no part of the claimed design.