Photorheological (PR) fluids are the fluids with light-tunable rheological properties and are very useful in a variety of applications. Cetyl trimethylammonium bromide (CTAB) micelles and ortho-methoxycinnamic acid (OMCA) based PR fluids have attracted recent attention because they require no special synthesis. It has been shown that in the presence of trans-OMCA, CTAB micelles form long and wormlike micelles, and upon irradiation by UV light, OMCA undergoes a photoisomerization from its trans to its cis form, and the viscosity of the micellar solution is reduced by 4 orders of magnitude. This is feasible mainly due to the alteration of the molecular packing at the micellar interface. Our Aim is to investigate the effect of OMCA on the microscopic dynamics of CTAB micelles using quasielastic neutron scattering and establish a correlation with the observed viscosity.