In this paper, we suggest to maximize the instantaneous and average throughput of Visible Light Communications (VLC). Two approaches are presented: The first one uses the Instantaneous Signal to Noise Ratio (ISNR) to derive the Optimal Packet Length (OPL) that maximizes the instantaneous throughput. The second approach uses the Average Signal to Noise Ratio (ASNR) to derive the OPL that maximizes the average throughput. Instantaneous throughput maximization using OPL allows up to 4.5 dB gains with respect to fixed packet length. Average throughput maximization using OPL allows up to 1.5 dB gains with respect to fixed packet length.