A portable optical device (104) for transmitting an image to the eye (6) of an observer, includes: a display (1) disposed on the same side of the observer's head (7) as the eye, so as to emit the image in front of the observer's head; an ocular dioptric surface (3); and redirection elements (4, 5, 8, 9) for guiding the image towards the dioptric surface. The device is disposed such that the image strikes the dioptric surface (3) originating from the side of the nose in relation to the eye (6) and the dioptric surface (3) then reflects the image towards the eye (6). Such a device is particularly suitable for the production of glasses that can be used to display a virtual or augmented reality.