A composition-dependent single Sellmeier oscillator model, developed for predicting the refractive index against composition behaviour for the three binary glass systems, SiO2-B2O3, SiO2-P2O5 and SiO2-GeO2, is extended to a double Sellmeier oscillator model. The inclusion of both composition-dependent u.v. and i.r. terms in the Sellmeier equation has enabled the wavelength dispersive properties of optical glass fibres; refractive index, material dispersion and profile dispersion, to be computed for any composition, in any one of these three binary glasses. Theoretical calculations, for particular compositions, of material and profile dispersions are compared with experimental measurements on fibres of the same compositions, fabricated by chemical vapour deposition.