I claim the ornamental design for the eyeglass holder, as shown and described.
FIG. 1 is a front view of the eyeglass holder according to the invention;
FIG. 2 is a side view of the eyeglass holder of FIG. 1;
FIG. 3 is a rear view of the eyeglass holder of FIG. 1; and,
FIG. 4 is an environmental view of the eyeglass holder of FIG. 1 installed on a cap and holding a pair of eyeglasses. The eyeglasses and cap shown in broken lines, form no part of the claim.