by Dan Roberts
(Updated: June 5, 2012)
The IMT is a micro-sized precision telescope, about the size of a pea, that is implanted in one eye in an outpatient surgical procedure conducted under local anesthesia. The IMT provides magnification of 3.0X or 2.2X, depending on the IMT model used. A magnified image is projected over a wide field of the retina to improve the ability to recognize images that were previously either difficult or impossible to see. The IMT is implanted in one eye of patients who present with untreatable late-stage AMD (end-stage AMD). The telescope provides central vision, while the non-implanted eye provides peripheral vision.
Stephen Lane, M.D., principal investigator at Associated Eye Care, Stillwater, MN who implanted six IMTs in VisionCare’s Phase I trial, commented, “We are excited about the potential the IMT provides for improving visual acuity and the quality of life for individuals with severe AMD. We are encouraged with the results produced in the Phase I trial and look forward to studying the IMT in a larger patient population in this Phase II/III evaluation.”
“We see many patients in the clinic with advanced AMD for whom we have no real viable treatment options. The IMT technology may give ophthalmologists a method of improving vision and function in the more than 500,000 U.S. patients who have bilateral permanent vision loss due to macular degeneration,” said vitreo-retina disease specialist and Phase I investigator, Baruch D. Kuppermann, M.D., Ph.D., University of California, Irvine.
Fourteen patients were implanted with the IMT in the Phase I trial. Patients were monitored for safety and efficacy. One year after implantation, the majority of patients gained three or more lines (a doubling) of distance or near visual acuity and improvement in their activities of daily living. The most common complication was transient inflammation.
Patients at over 25 leading medical universities and ophthalmic centers into its US Phase II/III pivotal trial for untreatable end-stage AMD and Stargardt’s macular dystrophy.
In a presentation to the joint meeting of the American Academy of Ophthalmology (AAO) and the European Society of Ophthalmology (SOE) in New Orleans, LA, on October 23-26, 2004, VisionCare reported that the ongoing Phase II/III trial was assessing the safety and efficacy of the IMT. Phase I trial results demonstrated that one year after implantation, 77% (10/13) of patients gained two or more lines of distance or near visual acuity and 62% (8/13) of patients gained three or more lines (a doubling) of visual acuity as measured on a standard (ETDRS) eye chart. The most common complication was transient inflammation.
On October 19, 2005, Paul Sternberg, M.D. and Henry Hudson, M.D., announced positive results from VisionCare’s Phase I/III clinical trials of the IMT. After one year, subjects showed a mean improvement of over 3 lines in both distance and near visual acuity. 90% exceeded the primary endpoint of the trial with a 2-line improvement. Significant improvement in quality of life and daily living activities was also measured. A 2-year follow-up has revealed no serious safety issues. In July 2006, however, the company suffered a setback when the IMT was voted down for approval by an FDA advisory panel.
The November 2006 issue of Ophthalmology (Volume 113, Issue 11, Pages 1895-2134) published an article titled “Implantable Miniature Telescope for the Treatment of Visual Acuity Loss Resulting from End-Stage Age-Related Macular Degeneration” (Hudson HL, Lane SS, Heier JS, Stulting RD, Singerman L, Lichter PR, Sternberg P, Chang DF, IMT-002 Study Group) which detailed the results from the IMT002 trial. 217 patients at 28 U.S. investigational sites had severe vision loss due to the characteristic central blind spot caused by end-stage macular degeneration. The publication reports 90% of patients met or exceeded the protocol-specified primary efficacy endpoint of visual improvement, defined as a 2-line gain in either distance or near vision on the study eye chart. The protocol stated the endpoint would be achieved if at least 50% of patients met this target.
At 1 year after the telescope implantation procedure, 67% of patients achieved a 3-line (doubling of vision) or greater improvement in their study eye distance visual acuity, compared with 13% of unimplanted fellow eye controls. Approximately 25% of telescope-implanted eyes achieved a 5-line or greater improvement in visual acuity, compared with 2% of fellow eyes. Loss of 3 lines or more was encountered in 1.6% of implanted eyes, compared with 3.1% of fellow eyes. Secondary efficacy outcome measures suggest improvement in patients’ vision-related quality of life and activities of daily living. On the National Eye Institute 25-item Visual Function Questionnaire, patients improved significantly from baseline (range 7 to 14 points) in 7 of 8 relevant vision-specific and psychosocial subscales, including General Vision, Social Functioning, and Dependency. Corneal endothelial cell density, a safety endpoint, was reduced 20% from preoperative at 3 months and 25% at one year (compared with the 17% protocol-specified target).
Patients enrolled in the study were at least 55 years of age and had central vision loss caused by disciform scars (end-stage wet AMD) or geographic atrophy (advanced dry AMD). Exclusion criteria included active choroidal neovascularization (wet AMD) or treatment of wet AMD in the preceding six months. Patients with early-stage AMD, mildly visually impairing AMD, or unilateral affection were not eligible.
The IMT002 trial was a prospective, open-label, multicenter clinical trial conducted under an investigational device exemption from the U.S. Food and Drug Administration (FDA). Patients averaged 76 years of age. The telescope prosthesis was generally well tolerated in the eye. 206 of the 217 enrolled patients had the device successfully implanted in their study eye, while 11 patients received a standard intraocular lens due to an aborted procedure. The most common complications or adverse events included transient intraocular pressure, transient corneal edema, iris prolapse, and inflammatory deposits on the device. There were 2 cases of corneal decompensation. The results were published online at www.ophsource.org/periodicals/ophtha/article/PIIS016164200600933X/abstract.
In November 2008, the American Journal of Ophthalmology* published two-year results from the Phase II/III IMT002 trial showing substantial visual acuity improvement in end-stage AMD patients. The study device has received CE Mark approval in Europe and is currently investigational and under regulatory review by the U.S. Food and Drug Administration.
The publication details the two-year safety profile of the device and found rates of cornea endothelial cell loss, while higher than conventional small-incision anterior segment eye surgery, were consistent with anterior segment procedures employing more similar incision sizes required for telescope implantation. According to one co-author of the study, the risks of surgery are outweighed by the benefits.
“The published data show improved visual acuity in end-stage AMD patients that was maintained over two years — a three-line improvement that we have previously shown makes a real impact on our patients’ independence and quality of life,” said Henry L. Hudson, M.D., lead author for the IMT002 study and retina specialist at Retina Centers, P.C. in Tucson, AZ.
At last, on March 27, 2009, the FDA’s ophthalmic device panel voted to recommend approval of the IMT. After 5 years of trials and prior submissions to the panel, the device now meets all of their requirements for safety and efficacy.
The FDA usually follows the recommendations of an advisory panel, but is not required to do so. The panel recommended approval of the device with conditions including post-approval surveillance and labeling suggestions. The panel decision was reached by a vote of 8 to 0.
“We are pleased with the panel’s recommendation for approval and will work closely with FDA to address the approval conditions,” said Allen W. Hill, CEO of VisionCare. “We look forward to providing the ophthalmic community a new treatment option to improve vision and quality of life for patients with untreatable, end-stage age-related macular degeneration.”
Dan Roberts, MD Support director, spoke to the panel shortly before the vote. “Until now,” he said, “nothing has offered long-term vision restoration for people in the advanced stage of the disease. That stage has traditionally been one of transition to nonvisual skills such as cane use and Braille. With the IMT, it may be possible for some of us to put that off indefinitely, and that gives us one more cannon to fire.”
On July 6, 2010, VisionCare announced that the FDA had approved the IMT for use in the retinas of qualified patients.
On September 8, 2011, the company announced that effective October 1, outpatient facilities would be able to obtain Medicare and Medicaid reimbursement for the IMT.
Finally, on November 10, VisionCare announced that the first patient had received the IMT. The patient was evaluated by and received the telescope implant procedure from ophthalmologists Henry L. Hudson, M.D., retinal specialist at Retina Centers, P.C., and Kristin Carter, M.D., anterior segment eye surgeon, both part of the CentraSight provider team in Tucson, AZ. The procedure was performed on an outpatient basis at Carondelet Health Network’s St. Joseph’s Hospital in Tucson.
Patients and physicians can find more information about the telescope implant and related treatment program at www.CentraSight.com.
For more information on the research, see www.visioncareinc.net or call (408) 872-0526.
*Hudson HL, Stulting RD, Heier JS, Lane SS, Chang DF, Singerman LJ, Bradford CA, Leonard RE; IMT002 Study Group. Implantable Telescope for End-Stage Age-related Macular Degeneration: Long-term Visual Acuity and Safety Outcomes. Am J Ophthalmol. 2008: 146; 664-673.
by August Colenbrander, M.D.
The Smith-Kettlewell Eye Research Institute and
California Pacific Medical Center, San Francisco
June 6, 2012
I believe that prospective patients should also know the following about the IMT.
(1) FDA approval of devices like these involves only a record of SAFETY, not of EFFECTIVENESS. (This is different for drugs, where safety and effectiveness are required).
(2) When patients choose for any treatment, they should be concerned not only about its effectiveness compared to doing nothing, but rather to its effectiveness compared to other available alternatives.
(3) All studies presented to the FDA compared the end result to the condition before surgery, without prior Low Vision therapy. Low Vision therapy was only recommended AFTER surgery.
(4) The new protocol explicitly requires a complete Low Vision workup BEFORE surgery. Only if they have been made aware of what can be achieved by non-surgical means and by traditional cataract surgery, can patients provide truly informed consent.
One group estimated that only 1% of those who are initially interested would qualify for actual implantation.
I hope that one of the results of this new requirement will be that more patients become aware of what traditional vision rehabilitation programs can provide. Equal or greater magnification can be provided with traditional means, without additional surgical risk and without disrupting binocular vision (as the IMT does, because of monocular implantation).
The statement that the magnification reduces the effect of the size of the scotoma is incorrect. A central scotoma forces the eye to fixate eccentrically. At the new fixation point (PRL) the retinal resolution is less; this requires magnification. The required magnification is related to the retinal function at the site of the PRL, not to the overall size of the scotoma.
Generally ignored is the fact that eccentric viewing also requires a re-calibration of eye and fixation movements. This adaptation is a cerebral function; it requires training and practice and cannot be achieved by any device. The IMT complicates this process by requiring different eye movement adaptations for the operated eye and for the fellow eye. This is a potential problem, especially for patients who have similar vision in both eyes.