A method of determining configuration of selective optical interferential filtering means (120; 220; 320; 322; 522; 620-1 - 620-n) for an optical device (100; 200; 300; 500; 600) customised for a particular user, the method comprising: providing a first set of parameters characterising, for the user, at least one range of wavelengths to be inhibited, and a degree of inhibition of the at least one range of wavelengths; determining at least one selected range of wavelengths of incident light to be inhibited, and an inhibition rate, based on the first set of parameters; providing a second set of parameters characterising, for the user, a degree of transmittance of incident light of the visible spectrum outside the at least one selected range of wavelengths; determining a transmittance, based on the second set of parameters; and configuring selective optical interferential filtering means (120; 220; 320; 322; 522. 620-1 - 620-n) based on the determined at least one selected range of wavelengths, the inhibition rate and the transmittance such that the selective optical interferential filtering means (120; 220; 320; 322; 522; 620-1 - 620-n) is operable to inhibit, at the determined inhibition rate, transmission of the at least one selected range of wavelengths of incident light, and to transmit, at the determined transmittance, incident light of the visible spectrum outside the at least one selected range of wavelengths, wherein the first set of parameters comprises physiological parameters of the user including whether the user suffers from a deterioration of the eye or is to be protected from a deterioration of the eye, in particular due to a degenerative process such as glaucoma, diabetic retinopathy, Leber's hereditary optic neuropathy, Age related Macular Degeneration, Stargardt disease retinitis pigmentosa or Best's disease and the second set of parameters comprises parameters of the intended use of the optical device (100; 200; 300; 500; 600),in particular, the degree of solar protection required, wherein the second set of parameters comprises parameters representative of the category of solar protection filter 1 to 3 as defined in Table 1 of the accompanying description, wherein the selective optical interferential filter (120; 220; 320; 322; 522; 620-1 - 620-n) is configured to inhibit transmission of incident light of wavelengths outside the at least one selected range of wavelengths by absorption, at a particular inhibition rate which is less than the determined inhibition rate. providing a first set of parameters characterising, for the user, at least one range of wavelengths to be inhibited, and a degree of inhibition of the at least one range of wavelengths; determining at least one selected range of wavelengths of incident light to be inhibited, and an inhibition rate, based on the first set of parameters; providing a second set of parameters characterising, for the user, a degree of transmittance of incident light of the visible spectrum outside the at least one selected range of wavelengths; determining a transmittance, based on the second set of parameters; and configuring selective optical interferential filtering means (120; 220; 320; 322; 522. 620-1 - 620-n) based on the determined at least one selected range of wavelengths, the inhibition rate and the transmittance such that the selective optical interferential filtering means (120; 220; 320; 322; 522; 620-1 - 620-n) is operable to inhibit, at the determined inhibition rate, transmission of the at least one selected range of wavelengths of incident light, and to transmit, at the determined transmittance, incident light of the visible spectrum outside the at least one selected range of wavelengths, wherein the first set of parameters comprises physiological parameters of the user including whether the user suffers from a deterioration of the eye or is to be protected from a deterioration of the eye, in particular due to a degenerative process such as glaucoma, diabetic retinopathy, Leber's hereditary optic neuropathy, Age related Macular Degeneration, Stargardt disease retinitis pigmentosa or Best's disease and the second set of parameters comprises parameters of the intended use of the optical device (100; 200; 300; 500; 600),in particular, the degree of solar protection required, wherein the second set of parameters comprises parameters representative of the category of solar protection filter 1 to 3 as defined in Table 1 of the accompanying description, wherein the selective optical interferential filter (120; 220; 320; 322; 522; 620-1 - 620-n) is configured to inhibit transmission of incident light of wavelengths outside the at least one selected range of wavelengths by absorption, at a particular inhibition rate which is less than the determined inhibition rate.