The use of visible-light communication (VLC) to complement radio-frequency systems in satisfying the ever-increasing user data demands has received particular interest since about two decades. One important issue in VLC networks is to address the multiple-access (MA) requirement. Non-orthogonal MA (NOMA) is a promising technique for multi-cell VLC networks, in particular, due to providing high spectral efficiency. However, its performance is highly impacted by the considered power allocation (PA). In this paper, we propose optimization of PA in NOMA-based VLC networks using particle swarm optimization. The presented results show that the optimized PA offers a higher performance in terms of the network achievable throughput and fairness, compared with non-optimized PA, while offering flexibility in controlling the desired performance criteria.