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Telescope may serve as permanent prosthesis for bilateral AMD
Ophthalmology Times
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Figure 1 Implantable miniature telescope [IMT (by Dr. Isaac Lipshitz)] positioned in the capsular bag projects a magnified image onto the macula. Part of the telescope tube projects anteriorly into the anterior chamber.
San Diego—An implantable miniature telescope in the capsular bag provides a permanent visual prosthetic device for patients who are legally blind from bilateral age-related macular degeneration (AMD). While there is a learning curve, an early assessment of the implantation indicates that anterior segment surgeons are familiar with the standard phacoemulsification and manual extracapsular surgical skills used for this procedure, according to David F. Chang, MD.

The IMT (by Dr. Isaac Lipshitz), is composed of two lenses within a glass tube measuring 4.4 mm in length and 3.6 mm in diameter. It is positioned within the capsular bag by means of an attached polymethylmethacrylate carrier platform that has long, C-loop haptics. When implanted, it provides the patient with 2X to 3X magnification.

"Importantly, the device [developed by VisionCare Ophthalmic Technologies Inc. with inventors and company founders Isaac Lipshitz, MD, and Yossi Gross] has been optically engineered to provide the patient with a much wider visual field when compared with that provided by a comparable external telescope," said Dr. Chang, clinical professor of ophthalmology, University of California, San Francisco, and a private practitioner in Los Altos.


Figure 2 The implantable telescope with the PMMA carrier and haptics.
During the American Society of Cataract and Refractive Surgery annual meeting, he reported 3-month data from the multi-center FDA phase II-III trial, which had enrolled 204 patients by last fall. All patients had poor visual acuity bilaterally as a result of AMD.

Implantation procedure Dr. Chang explained the device is implanted in only one eye, intending for the patient to use the magnified image for central vision tasks. The fellow eye without the telescope provides peripheral vision. The natural crystalline lens is removed using a standard phacoemulsification procedure, and the telescope is placed within the capsular bag.

Part of the telescope tube protrudes into the anterior chamber through the pupil. High-resolution ultrasound biomicroscopy has confirmed that there is at least 2 mm of corneal clearance.

"Once the crystalline lens has been removed, the limbal incision is enlarged to 11 mm, as would be done for a manual extracapsular procedure. The telescope cannot be implanted unless both the capsulorhexis and capsular bag are intact. The capsulorhexis should be larger than usual (approximately 6.5 mm)," Dr. Chang explained.


Figure 3 Slit lamp image of the implanted telescope in the capsular bag viewed through a dilated pupil. Anterior capsular fibrosis is visible, showing capsulorhexis fixation of the flat carrier
"Because of the high vertical profile of the device, the major concern during implantation is corneal touch and endothelial cell loss. Therefore, the incision must be adequately large, and a generous amount of retentive ophthalmic viscosurgical device (OVD) should be used.

"In addition, the implant should be inserted with a relatively swift and decisive motion," he added. "Otherwise, with such a large incision, all of the OVD will leak out, resulting in collapse of the cornea."

At the 3-month examination, the mean endothelial cell loss was about 18% to 20%; however, there was a trend toward less cell loss with greater surgical experience.

The device was found to center extremely well within the capsular bag.

"We have not had any cases of corneal decompensation. Two of the telescopes were explanted because of problems with the optics," he reported.

The 3-month data indicated that 89% of the patients had gained at least two lines on an ETDRS chart, and 75% had gained at least three lines of distance or near vision.


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