  We study prompt optical emission from reverse shocks in the wind-type
gamma-ray bursts. The emission is evaluated in both the thick and thin shell
regimes. We discuss the angular time delay effect and the post-shock evolution
of the fireball ejecta, which determine the decay index of the prompt optical
emission and the duration of the radio flare. We discuss distinct emission
signatures of the wind environment compared with the constant interstellar
medium environment. We also present two recipes for directly constraining the
initial or early time Lorentz factor of the fireball using the reverse and
forward shock optical afterglow data for the wind case.
