Certain embodiments of the invention may include optimized trench-assisted ultra large area (ULA) optical fibers. According to an example embodiment of the invention, a trench-assisted optical fiber, optimized for figure-of-merit (FOM) performance, is provided. The optical fiber includes a core region having a longitudinal axis, a shelf region surrounding said core region, a cladding region surrounding said shelf region, said core and shelf and cladding regions configured to support and guide the propagation of signal light in a fundamental transverse mode in said core and shelf regions in the direction of said axis. The optical fiber further includes a core effective area (Aeff) of between 135 μm2 and about 170 μm2; and an index profile having a figure of merit (FOM) frontier distance less than about 0.7 dB.