The Ophthalmic Devices Panel of the Medical Devices Advisory Committee met on July 14, 2006, in an open session.
The Implantable Miniature Telescope (IMT) is indicated for use in adult subjects with bilateral, stable, untreatable moderate to profound central vision impairment due to macular degeneration.
The IMT is a visual prosthetic device which, when combined with the cornea, constitutes a telephoto lens for improvement of visual acuity in subjects with bilateral moderate to profound macular degeneration. The IMT device is surgically implanted in the posterior chamber of the eye, in place of the eye's crystalline lens and is held in position by haptic loops.
The IMT device contains two micro lenses, which magnify objects in the central visual field, allowing the patient to see without the need for external low-vision aids. A magnified image is projected by the IMT implant onto the retina, enabling the patient to recognize and identify objects that could not otherwise be seen. The IMT device is available in two models: Wide Angle (WA) 2.2X, and Wide Angle (WA) 3.0X, which provide nominal magnification of x2.2 and x2.7, respectively.
Both models are designed predominantly for the restoration of intermediate to far vision (increasing the ability to view objects several meters away from the patient). The addition of conventional spectacles provides correction for near vision activities.
The IMT device is implanted in one eye only. The implanted eye provides central vision, while the fellow eye continues to be used for peripheral vision. The IMT implant is composed of three primary components; a fused silica capsule that contains optical elements, a clear polymethylmethacrylate (PMMA) carrier, and a blue PMMA light restrictor. The optical component is snap-fitted into the carrier. One of the internal components (not in contact with body fluids or tissue) of the IMT implant contains stainless steel, which may interfere with the safe use of Magnetic Resonance Imaging (MRI). Until MRI compatibility of the IMT implant has been established, the use of MRI is contraindicated, as stated in the proposed labeling.
The sponsor conducted a prospective multi-center clinical trial utilizing twenty-eight (28) clinical sites and enrolling a total of 218 consecutive subjects. The primary SafetyEndpoint for this study was the mean percentage endothelial cell density (ECD) loss less than or equal to 17% at one year post IMT implantation. Secondary safety endpoint was preservation of best corrected visual acuity. Specifically, no more than 10% of implanted eyes were to experience a loss of more than 2 lines of either near or distance BCVA without a corresponding improvement in BCVA (gain of 2 lines or more).
The primary effectiveness endpoint for this study was defined as an improvement of 2 lines or greater in either near or distance best corrected acuity in 50% of the implanted eyes at 12 months post-implantation. Quality of Life surveys (Activities of Daily Living (ADL) and National Eye Institute Visual Function Questionnaire (NEI-VFQ-25)) were secondary measurements of efficacy.
At 1 year post-implantation, the sponsor reported that the mean endothelial cell density had decreased 25.3% in the eyes that had received the IMT, and that 90.1% of implanted eyes had an improvement of ≥2 lines in either near or distance best corrected acuity.
On a 10-3 vote, the panel recommended that the VisionCare Technology PMA be found “not approvable”, i.e. the data did not provide reasonable assurance that the device is safe and effective under the conditions of use prescribed, recommended, or suggested in the proposed labeling.
The panel decision was based on unresolved safety concerns, in addition to uncertainty regarding the efficacy of the device. The panel noted that the absence of morphometric analysis of the endothelial cell density data did not allow them to adequately evaluate the chronic rate of endothelial cell density loss, a major safety concern for this device, in eyes that had received the IMT. In addition, the panel noted confounding factors that may have influenced the efficacy of the device.
The transcriptionist for this meeting was Neal R. Gross & Company, 1323 Rhode Island Avenue, NW, Washington, D.C. 20005, (202) 234-4433.
Contact: Sara T. Thornton, Executive Secretary, 301-594-2053 x 127.