Hologram processing is the primary bottleneck and contributes to more than 50% of energy consumption in battery-operated augmented reality (AR) headsets. Thus, improving the computational efficiency of the holographic pipeline is critical. The objective of this paper is to maximize its energy efficiency without jeopardizing the hologram quality for AR applications. Towards this, we take the approach of analyzing the workloads to identify approximation opportunities. We show that, by considering various parameters like region of interest and depth of view, we can approximate the rendering of the virtual object to minimize the amount of computation without affecting the user experience. Furthermore, by optimizing the software design flow, we propose HoloAR, which intelligently renders the most important object in sight to the clearest detail, while approximating the computations for the others, thereby significantly reducing the amount of computation, saving energy, and gaining performance at the same time.We implement our design in an edge GPU platform to demonstrate the real-world applicability of our research. Our experimental results show that, compared to the baseline, HoloAR achieves, on average, 2.7× speedup and 73% energy savings.