Advances in Cataract Surgery

Majed Alkharashi; Walter J Stark; Yassine J Daoud


Expert Rev Ophthalmol. 2013;8(5):447-456. 

In This Article

Implantable Miniature Telescope

In July 2010, the FDA approved the Implantable miniature telescope TM (IMT, VisionCare Ophthalmic Technologies Inc., Saratoga, CA, USA). The implantable miniature telescope (IMT) is a system which magnifies objects to improve vision in patients with end-stage age-related macular degeneration (AMD). It is indicated for monocular implantation in patients with stable, but severe to profound vision impairment (best corrected distance visual acuity 20/160–20/800) caused by bilateral central scotomas associated with end-stage age-related macular degeneration, a visually significant cataract and who achieve at least a 5-letter improvement on the visual acuity chart using a trial external telescope. Two models are available: one with 2.2-times magnification and the other with 2.7-times magnification. The device's glass cylinder housing the micro-optics is 4.4 mm long and 3.6 mm in diameter. The rigid haptic loops are 13.5 mm in diameter. The device is placed in the capsular bag while the anterior aspect protrudes through the pupil by 0.1–0.5 mm. The prosthesis projects an enlarged image of the patient's central visual field onto the retina; thus reducing the size of the scotoma relative to the objects in the central field of vision. The implanted eye sees 20–24 wide field of view due to the enlarged image projection.

The IMT has shown promise with 59.5% of 173 IMT-implanted eyes gaining three lines or more of BCVA compared to 10.3% of 174 fellow control eyes (p < 0.0001) after 2 years of follow-up. Meanwhile, 0.6% of 173 telescope-implanted eyes lost three lines or more compared to 7.5% of 174 fellow control eyes (p = 0.0013). Two cases of corneal edema in IMT-implanted eyes required grafts between 9 and 12 months.[50] There were no cases of corneal decompensation between 1 and 2 years after surgery. The mean endothelial cell density stabilized after the first year through the second year.[51]