Area bound for a surface in a strong gravity region

For asymptotically flat spacetimes, using the inverse mean curvature flow we show that any compact 2-surface, S-0, whose mean curvature and its derivative for the outward direction are positive in a spacelike hypersurface with non-negative Ricci scalar satisfies the inequality A(0) <= 4 pi(3Gm)(2), where A(0) is the area of S-0 and m is the total mass. The upper bound is realized when S-0 is the photon sphere in a hypersurface isometric to a t = const. slice of the Schwarzschild spacetime.