PHP device aids CNV detection

November 1, 2009

A new device for at-home monitoring of age-related macular degeneration is a promising tool for early detection of choroidal neovascularization.

New York-A new device for at-home monitoring of age-related macular degeneration (AMD) is a promising tool for early detection of choroidal neovascularization (CNV), as demonstrated by high specificity and sensitivity rates found in a recent evaluation. The AMD monitor (ForeseeHome) achieved 84% specificity and 85% sensitivity in detecting CNV.

The home PHP device was developed in Israel by Notal Vision and will be distributed in the United States by Sightpath Medical. The technology is the same as that employed in the Foresee PHP (Reichert Ophthalmic Instruments), which is used in clinic settings to monitor the conversion from dry to wet AMD. However, several software and hardware modifications were made for home usage. The monitor uses preferential hyperacuity perimetry (PHP) to quantify the extent of visual field abnormalities associated with CNV.

The home monitoring device has two important implications for patients, according to Dr. Loewenstein. One is detection of the development of neovascular AMD (CNV) when dry AMD is already present. It also can benefit patients who have successfully undergone treatment for CNV and are no longer receiving monthly therapy. In many instances, neovascularization is apparent during the follow-up examination or deteriorating vision has prompted patients to see the physician before their next scheduled visit. By using the monitoring device, these individuals might be able to detect recurrence earlier, resulting in a smaller decline in visual acuity.

Dr. Loewenstein cautioned that the home monitoring device is not intended to replace visits to the ophthalmologist for routine follow-up or treatment. She added that to receive the most benefit from the device, patients should perform monitoring several times a week.

Patient compliance

The research presented at the Retina Congress included a study of the sensitivity and specificity of a single test with the monitoring device in the detection of CNV among patients with intermediate AMD. A second study evaluated long-term compliance in usage frequency. For the single-test study, inclusion criteria were intermediate or neovascular AMD, age >50 years, and visual acuity >20/200. This study enrolled 43 subjects with intermediate AMD and 34 with newly diagnosed CNV retrospectively; a prospective (validation) arm included 22 subjects with intermediate AMD and 32 with newly diagnosed CNV.

After a short training session, these patients performed a single, unsupervised test with the monitoring device. Fluorescein angiogram photos obtained the same day were sent to a reading center for grading. The high sensitivity and specificity (85% and 84%, respectively) are clearly acceptable for diagnostic devices, although, as with any such device, there will be some false negatives and false positives, Dr. Loewenstein said.

"We also found that the sensitivity was not dependent on the anatomic characteristics of the lesion. It didn't matter if the lesion was exactly under the center of the fovea or was juxtafoveal, if it was smaller or bigger, or it was classic or occult; the sensitivity was the same," she added.

Criteria for the longitudinal study were intermediate AMD, age >50 years, and VA >20/60. These patients were followed for several months. Results showed that usage frequency was consistent, averaging about 3.5 times per week. An FDA application for clearance of the device is pending. It is expected to be available in the United States in 2010 and will be packaged with an unpacking and set-up guide, the number of a toll-free support line, an introductory video clip, and a hands-on tutorial.