The Food and Drug Administration announced that it approved the Implantable Miniature Telescope to improve vision in some patients with end-stage age-related macular degeneration.
Surgically implanted in one eye, the IMT replaces the natural lens and provides an image that has been magnified more than two times.
"This innovation has the potential to provide many people with an improved quality of life," said Jeffrey Shuren, MD, JD, director of the FDA's Center for Devices and Radiological Health.
The IMT is available in two models: one that provides 2.2 times magnification and another 2.7 times magnification. The IMT is designed to magnify and project images onto a healthy portion of the retina. The IMT is intended to be implanted in only one eye; the non-implanted eye is used for peripheral vision.
The IMT is used in patients ages 75 years and older with stable severe to profound vision impairment caused by blind spots (bilateral central scotoma) associated with end-stage AMD. These patients also have evidence of a visually significant cataract.
Patients agree to undergo training with an external telescope with a low-vision specialist prior to implantation to determine whether adequate improvement in vision with the external telescope can be obtained and to verify if the patient has adequate peripheral vision in the eye that would not be implanted. Patients also agree to participate in a postoperative visual training program.
In a 219-patient, multicenter clinical study of the IMT, 90 percent of patients achieved at least a two-line gain in either their distance or best-corrected visual acuity, and 75 percent of patients improved their level of vision from severe or profound impairment to moderate impairment.
Because the IMT is a large device, implantation can lead to extensive loss of corneal endothelial cells and chronic endothelial cell loss. The chronic rate of endothelial cell loss is about 5 percent per year. Significant losses in ECD may lead to corneal edema, corneal decompensation and the need for corneal transplant. In the study, 10 eyes had unresolved corneal edema, with five resulting in corneal transplants. The calculated five-year risk for unresolved corneal edema is 9.2 percent, for corneal decompensation 6.8 percent, and for corneal transplant 4.1 percent.
To ensure that the risks of IMT implantation are sufficiently and consistently communicated to patients, the FDA and the manufacturer created detailed labeling, including an Acceptance of Risk and Informed Decision Agreement, which patients must complete prior to IMT implantation. The agreement provides a guide for patients and their physicians to discuss the risks associated with IMT implantation.
As a condition of FDA approval, the manufacturer, VisionCare Ophthalmic Technologies, of
ISTA Initiates Study of Bepreve As a Nasal Spray
ISTA Pharmaceuticals has initiated a Phase I/II clinical study of bepotastine besilate nasal spray for the treatment of symptoms associated with seasonal allergic rhinitis.
The randomized, placebo-controlled, parallel-group study will evaluate the safety and efficacy of three concentrations of bepotastine besilate, dosed twice daily, in an environmental exposure chamber model of allergic rhinitis caused by natural exposure to seasonal allergens. The study also will assess the pharmacokinetics of the investigational nasal sprays.
Following initial screening, 96 patients will be randomized into the study. During the study, patients will be exposed to pollen in the EEC and will grade their individual symptoms at select time intervals prior to and following dosing with bepotastine besilate nasal spray or placebo. Reported symptoms will include both nasal symptoms and ocular symptoms. Safety will be evaluated based on several variables, including adverse events, electrocardiograms and the mean grades for questions on a brief satisfaction and tolerability questionnaire completed at the end of the study. In addition, pharmacokinetic data on the three dose concentrations of bepotastine besilate nasal spray will be assessed based on blood draws from a subset of patients.
ISTA expects to complete the study and announce preliminary results in the fall of 2010.
OCT May Help Detect Early MS
Optical coherence tomography shows promise as a way to diagnose multiple sclerosis in its very early stages, and to track the effectiveness of treatments, researchers from UT Southwestern Medical Center have found in a multicenter study.
"This technique has the potential to provide a powerful and reliable assessment strategy to measure structural changes in the central nervous system, both for diagnostic purposes and in clinical trials to monitor whether potential treatments can prevent deterioration or restore nerve function," said Elliot Frohman, MD, professor of neurology and ophthalmology, director of the Multiple Sclerosis Clinical Center at UT Southwestern and co-senior author of the study, which appeared in the June issue of Annals of Neurology.
"An ophthalmologist might someday be able to use OCT to identify retinal thinning during a routine eye exam and consider MS as a prime diagnosis," Dr. Frohman said. "However, this prospect is a long way off."
Retinal thinning can occur as a result of multiple sclerosis, but this study, Dr. Frohman said, is the first to track such thinning over time in a single group of patients. The study involved 299 patients with MS who were tracked for six months to 4.5 years.
The researchers found that the retinas thinned significantly with time, and patients often concurrently lost visual sharpness. Overall, the study indicated that OCT is reliable, easy to use and sensitive to changes over time. It could also be used with current clinical measures, the researchers said.
Future studies are needed to ascertain whether OCT can characterize the effectiveness of treatments, Dr. Frohman said.
Prior CNV Increases Transplant Rejection And Failure Rate
A team of German and British researchers has confirmed that failure and rejection of transplanted corneas are more likely in patients whose eyes exhibit corneal neovascularization prior to surgery. The meta-analysis report appeared in July's Ophthal-mology. The findings also suggest a new treatment approach that could improve transplant success rates.
Claus Cursiefen, MD, and colleagues reviewed 19 studies involving nearly 24,500 corneal transplants. "The presence of corneal neovascularization before surgery makes it about 30-percent more likely that the transplant will fail, and more than doubles the risk of graft rejection," said Dr. Cursiefen. "We also found that the risks of failure and rejection rise with the extent of vascularization—the more extensive the corneal neovascularization, the higher the risks."
These findings suggest that patients who have corneal neovascularization might benefit from treatment before transplant surgery with antiangiogenics, such as bevacizumab or ranibizumab, or with another type of drug that works at the level of gene transcription to discourage vessel growth; one such drug, GS101, is now in clinical trials. This "preconditioning" approach is worthy of thorough testing and assessment, the researchers say.
"In the future, preconditioning a vascularized cornea before transplantation may be a useful strategy to promote survival of the graft," Dr. Cursiefen said.
More than 40,000 transplant surgeries are performed annually in the
Dr. Cursiefen's review found that increasing age and male gender appear to be additional, independent risk factors for graft failure, but not for graft rejection; he says further study is needed to confirm these findings.
Prism Lenses Ease TBI Symptoms
A recent study of 43 patientswith traumatic brain injury shows strong evidence that symptoms of headache, dizziness and anxiety in some patients with traumatic brain injury potentially could be alleviated or even eliminated with specialized eyeglass lenses containing prisms. The paper was published in the April issue of Physical Medicine and Rehabilitation. "This represents a new approach to the treatment of post-concussive symptoms," says Mark S. Rosner, MD, adjunct clinical instructor in the department of emergency medicine at the University of Michigan Medical School. "Vision was known to be affected by TBI, but now it appears that the vision abnormalities caused by the TBI are causing the other post-concussive symptoms."
The study suggests that TBI appears to be causing visual image misalignment—or vertical heterophoria. To correct this misalignment and prevent double vision, the eye muscles are utilized to force the eyes back into proper alignment. This causes the eye muscles to become overworked, strained and fatigued, which accounts for many post-concussive symptoms, including headaches, dizziness, anxiety and neck pain. The use of prismatic eyeglass lenses to realign the images and reduce or eliminate eye muscle overwork led to a 71.8-percent reduction of patients' symptoms.
TBI affects 15 to 20 percent of our servicemen and women returning from Iraq and Afghanistan—caused mostly by explosions—and approximately 2 million people per year in the United States—caused mostly by falls, auto accidents and sports injuries. Approximately 10 to 25 percent of patients with TBI still have significant post-concussive symptoms one year after their injury. The overlap of TBI and vertical heterophoria symptoms was significant: headaches, neck ache, upper back pain, dizziness, nausea, anxiety and reading difficulties. To date, no single unifying cause of TBI symptoms had been identified.
