Described herein are various embodiments of eyewear provided for advantageous use in sports and work, as well as in casual activity. According to one embodiment, an eyeglass can include a frame and an eyecup assembly coupled to the frame. The eyecup assembly can include a resilient side member that has a first proximal portion that is fixed relative to the frame and a second distal portion that is movable relative to the frame and biased toward the frame. The eyecup assembly can also include an adjustment mechanism that is coupled to the resilient side member and positioned at least partially between the resilient side member and the frame. The adjustment mechanism can be selectively operable to flex the resilient side member to move the second distal portion away from the frame and to un-flex the resilient side member to move the second distal portion toward the frame.