Patients who have central vision reduction or loss due to diseases like age-related macular degeneration may benefit from viewing magnified images to compensate for such reduction or loss. Several factors determine the effectiveness of magnified imaging for these patients. These include magnification gain, field-of-view, working distance, user-friendliness of the system, etc. In this paper, the engineering design parameters of an intraocular telephoto system is reviewed. Such a system consists of a high plus spectacle lens and a high minus intraocular lens (IOL). Magnification, a key performance indicator of the system, is determined by adjustment of the four following parameters: spectacle power, intraocular lens power, fitting distance, object distance. Field-of-view and fixation field may be limited by the fitting distance and the spectacle size, at a given magnification. Magnification can be increased by either decreasing the spectacle power and/or the IOL power. However, both methods move the spectacle lens farther from the eye, increasing fitting distance. A graph relates magnification to the four parameters. A reasonably useful magnification range is achieved within the practical constraints on distances and lens powers. Design constraints on the field-of-view and fixation field will be discussed. Aberration reduction will be briefly mentioned.