Our previous research highlighted adverse visual effects after wearing a binocular head-mounted display (HMD) for a 10 min stereoscopic visualization task. We have since proposed a theoretical, explanation based on the conflict between the depth. Such cues presented by image disparity and image focal depth. Such conflict, however, is not evident in all HMD configurations, and we replicated our early trials using a new-generation bi-ocular HMD produced by Virtuality Entertainment Ltd. Using similar, conventional optometric procedures with 50 participants, we observed no problems in the use of this display for immersion periods of to 30 min. This study demonstrates that effective HMDs can be produced through careful design and precision engineering. It also suggests a difference between the presentation of binocular and bi-ocular images and the requirements that they place on the visual system. Factors to consider in the future development of binocular displays are discussed.