The Optical Functional Advantages of an Intraocular Low-Vision Telescope

Abstract

An implantable miniaturized telescope (IMT) for low vision has recently been developed. Surgically inserted into only one eye of patients with bilateral central visual loss, the IMT provides a nominal magnification of 3.0x and a field-of-view of 6.6 degrees (9.2 degrees for the 2.2x magnification version). Theoretical concerns have been raised regarding the ability of patients to function with a large interocular magnification difference, the impact of the monocular restriction of the field-of-view, and the impact of this design on depth perception. This article addresses these concerns regarding the design of the IMT in comparison with spectacle-mounted telescopes and combined intraocular lens/spectacle (or combined contact lens/spectacle) telescopic systems. The effective field-of-view (as determined by the combination of both the field-of-view and the field-of-fixation), the effects of head motion and the vestibular reflex, and the disruption of stereo depth perception with a monocular device are considered here. Physiological optics considerations of these issues show that the IMT may have important advantages over other designs of magnification devices for patients with age-related macular degeneration.

Optical analysis to predict outcomes after implantation of a double intraocular lens magnification device

“…[11][12][13][14][15] The Â3.0 intraocular miniaturized telescope 11 has several advantages including high plus-powered lenses and external telescopes and an increase in the visual field (compared with external telescopes) and depth of focus. The patient's functional and cosmetic comfort is another benefit.…”

The Implantable Miniature Telescope and Quality of Life Improvements in Patients with End-Stage Age-Related Macular Degeneration

“…The fellow eye is used for peripheral vision, while the IMTimplanted eye is used for central vision and details. The device is available in two magnification powers: 2.2X and 2.7X, with full field view of 24° and 20°, respectively [74,75]. The 2.7X device is almost exclusively used in the United States, because 5-year data revealed more visual gains over time as disease progressed than with the 2.2X device [76].…”

An aspheric intraocular telescope for age-related macular degeneration patients

“…They are formed by two intraocular lenses (with positive and negative dioptric power) implanted into the eye after cataract surgery [7][8][9][10][11], or using a single lens that contains two mirrors forming a Cassegrain telescope [12]. At least three of these devices are in clinical use today.…”

“…At least three of these devices are in clinical use today. The Implantable Miniaturized Telescope (IMT; VisionCare Ophthalmic Technologies, Saratoga, CA) [7,8,13] consist of two lenses embedded in a cylinder glass tube with two optical windows that creates an air space around the lenses to achieve magnification between 2.2X and 3X depending on the viewing distance. The tube is 4 mm length and is implanted in the capsular bag using the iris to support and center the optical system.…”