The numerical aperture, the acceptance angle, the dispersion per unit length and the modal dispersion are important parameters in optical fibre characterization. Optical anisotropy produced in fibres undergoing bending gives valuable information for the characterization of these fibres. The present work provides a sensitive and analytical new technique to examine the influence of bending on single-mode optical fibres measuring, with a high spatial resolution, the radial changes in the previous fibre parameters due to bending. Multiple-beam Fizeau fringes crossing perpendicularly a bent fibre immersed in a matching silvered liquid wedge have been used successfully to determine the variation in the fibre index profile as a function of the fringe shift with accuracy 1 × 10⁻⁴. Mathematical expressions are given utilizing the measured fringe shift to characterize the bent fibre and to determine its radial parameter profiles.