We present the design and implementation of an optical see-through head-mounted display (HMD) with addressable focus cues utilizing a liquid lens. We implemented a monocular bench prototype capable of addressing the focal distance of the display from infinity to as close as 8 diopters. Two operation modes of the system were demonstrated: a vari-focal plane mode in which the accommodation cue is addressable, and a time-multiplexed multi-focal plane mode in which both the accommodation and retinal blur cues can be rendered. We further performed experiments to assess the depth perception and eye accommodative response of the system operated in a vari-focal plane mode. Both subjective and objective measurements suggest that the perceived depths and accommodative responses of the user match with the rendered depths of the virtual display with addressable accommodation cues, approximating the real-world 3-D viewing condition.