Glide the stick onto a clean fingertip, then tap a generous, even layer around the orbital bone and upper eye contour before face sunscreen. This fragrance-free drugstore mineral SPF 50 is specifically intended for fragile areas around the eyes, though it is an eye-area sunscreen rather than a treatment eye cream.
Keep it out of the eyes and off the lash line, reapply when outdoors, and add sunglasses. A mineral stick can leave some cast; do not solve that by applying less.