Home Testing for AMD
CLINICAL TRIAL SPOTLIGHT
Home Testing for AMD
An Israeli company has begun clinical trials on a device for home use.
ANDREW E. MATHIS, PhD, MEDICAL EDITOR
Imagine being able to provide age-related macular degeneration (AMD) patients with the ability to detect the onset of choroidal neovascularization (CNV). Treatment could be initiated while vision was still preserved and lesion was small, which substantially increases the likelihood for good and functional visual outcome. Notal Vision Ltd. (Tel-Aviv, Israel) is in the process of recruiting for 3 clinical trials of just such a device, with a fourth trial to begin enrolling soon.
The device, called the Home Macular Perimeter (HMP) and branded under the name Foresee Home, is currently in observational, prospective trials in the United States and Israel to determine how sensitive the device is in detecting CNV due to AMD over a 3-month period.
Yair Alster, MD, chief technical officer with Notal Vision, answered some questions for Retinal Physician about HMP and what its possible future looks like. "The current usability trials with intermediate and CNV patients are to demonstrate that the target population — dry AMD patients — can receive a packed home device, as they might in real-life situation, unpack it, set it up, and run tests on it," Dr. Alster said. "Another study is an efficacy trial to demonstrate that the Foresee Home can identify functional abnormalities in patients with CNV on a '1-encounter basis.'"
HOW IT WORKS
So what kind of defects will the home device be able to detect? According to the Notal Vision's brochure, the HMP uses "a method based on the human visual function of hyperacuity, which gives it the capability of detecting functional changes." Hyperacuity (also termed 'Vernier acuity') is defined as the ability to perceive a difference in the relative spatial localization of two or more visual stimuli.
The company information continues, "Hyperacuity stimuli are highly resistant to retinal image degradation and are thus also suitable for assessing retinal function in patients with cataract or opaque media for other reasons. No systematic variation of hyperacuity threshold had been found with increasing age in 1 study group of patients whose ages ranged from 20 to 85 years. Retinal pigment epithelium elevation, such as that which occurs in AMD, causes a shift in the regular position of photoreceptors. It is hypothesized that such a shift causes an object to be perceived at a different location from its true location in the visual field. This perceived shift in object location, which is recorded by the HMP, takes advantage of the human phenomenon of hyperacuity and may be, in fact, the anatomical explanation for metamorphosis."
Another area of study for Notal Vision will be the efficacy of the software with which the Foresee Home comes packaged. The company brochure states, "The HMP software is a screen-based application performed by the HMP Device. The patient's responses are recorded and automatically analyzed by a predesigned algorithm. That analysis reveals any changes in the visual field that warrant visiting an eyecare professional, while routine continued monitoring is recommended in case there had been no change."
And what does Notal Vision have to say about the accessibility of its software? "The test is intuitive and easy to use," the brochure states, "thus suitable for an elderly population. Actual testing takes about 3 minutes."
WHERE IT ENDS
Asked about the study endpoints, Dr. Alster said, "We anticipate that 80% of the target population will be able to use the device without any personal training. The efficacy trial endpoint is that 80% of patients with early CNV will demonstrate visual field defects on the home device."
Data collection is already going forward, with initial results expected within a few months. While these initial trials are relatively small, regulatory studies planned for the future will enroll in the area of 200 patients. "The regulatory studies are planned to be initiated shortly after the end of September 2008," Dr. Alster said. RP
Retinal Physician, Issue: April 2008