The intensity attenuation of a step-index optical fiber under localized pressure is investigated using the elasto-optical theory and the principles of geometrical optics. A model with a Gaussian variation of the refractive index in the axial direction is used to evaluate the effect of applied pressure on the external coating of the fiber. The results are compared with experimental measurements obtained using a prototype of an optical fiber pressure sensor. (C) 2013 Elsevier B.V. All rights reserved.