Eyeglass adapted for providing at least an ophthalmic vision and a supplementary vision to a wearer of said eyeglass, and comprising: - a front face and a back face, intended to be oriented respectively away from and towards an eye of the wearer; - a light-refracting transparent material comprised between the front face and the back face; and - a light-conducting element located in the light-refracting transparent material, and adapted to output a supplementary light between the front face and the back face of the eyeglass, through an exit face of said light-conducting element and towards the wearer's eye, the ophthalmic vision corresponding to a natural image formed by light transmitted by the eyeglass from the front face to the back face thereof, and the supplementary vision corresponding to a supplementary image to be viewed by the wearer and formed by the supplementary light, the light-conducting element being further transparent for the light of the ophthalmic vision, said eyeglass further comprising: - a transparent active device adapted for producing a variable optical power depending on a control signal supplied to said transparent active device, with first and second values for said variable optical power which are different from each other and correspond respectively to a first and a second state of the transparent active device, said transparent active device in the first state being effective for the supplementary light, and the first value of the variable optical power being suitable for the supplementary image to appear sharp to the wearer, and said transparent active device in the second state being effective for the light of the ophthalmic vision transmitted through the exit face of the light-conducting element, and the second value of the variable optical power being suitable for the natural image to appear sharp to the wearer, the front face and the back face of the eyeglass being used for providing the wearer with an ametropia correction effective for the ophthalmic vision, and the transparent active device cooperating with the back face of the eyeglass for correcting the wearer's ametropia for the supplementary vision, depending on the location of the supplementary image as output directly by the light-conducting element, characterized in that the transparent active device is located between the exit face of the light-conducting element and a portion at least of the back face of the eyeglass, and in that the second state is a default state of the transparent active device, said default state being effective when the power supply of the transparent active device is off or exhibits an operation failure. - a front face and a back face, intended to be oriented respectively away from and towards an eye of the wearer; - a light-refracting transparent material comprised between the front face and the back face; and - a light-conducting element located in the light-refracting transparent material, and adapted to output a supplementary light between the front face and the back face of the eyeglass, through an exit face of said light-conducting element and towards the wearer's eye, - a transparent active device adapted for producing a variable optical power depending on a control signal supplied to said transparent active device, with first and second values for said variable optical power which are different from each other and correspond respectively to a first and a second state of the transparent active device,