Home testing device may help monitor patients at risk for CNV development

Anat Loewenstein

A device designed for in-home, self-administered testing may find utility in monitoring patients with intermediate age-related macular degeneration, while other potential uses are being explored.

The ForeseeHome (Notal Vision) device is engineered based on preferential hyperacuity perimeter technology, which in previous studies has been shown “to detect and quantify the severity of visual defects associated with the development of [choroidal neovascularization] such as metamorphopsia and scotoma,” researchers wrote in a study recently published in Retina.

In the test, patients are tasked with identifying and marking locations of artificially displaced dots on horizontal or vertical dotted lines. Patients may perceive additional displaced dots if the line is flashed at the spot of a CNV lesion.

Previously, this type of test was only available in a clinical setting and required an operator to administer it. In the recent Retina study, a home version of the test displayed a high level of specificity and sensitivity in discriminating newly diagnosed CNV and intermediate AMD.

Study results

The study consisted of a retrospective and a prospective phase. In the retrospective portion, 109 consecutive patients with intermediate AMD or recent onset CNV were recruited from eight clinical centers in Israel. Because a computer mouse is used to perform the test, training was offered for use of that peripheral, but prior computer experience was not required in this phase of the study. Of the 109 patients, 14 had unreliable tests; 18 additional patients were excluded due to geographic atrophy, early AMD or poor-quality photographs.

“We have found out that once a patient possesses the knowledge of using a PC mouse, his/her training to use the device is rather simple with a very high success rate,” Anat Loewenstein, MD, chair of ophthalmology at the Tel Aviv Sourasky Medical Center, said. Dr. Loewenstein is a consultant to Notal Vision.

“The ergonomic and user interaction development of the device is clearly geared towards the target population and worked well with our patients,” she said.

In a separate study, researchers found that approximately 80% of elderly patients can successfully operate the device and that use of selection criteria improves the rate of correct self-administration to around 97%.

As a comparator, all patients underwent a clinical evaluation that was used to evaluate the accuracy of the device. According to the study, abnormal test results were identified in 29 of 34 eyes with CNV and in seven of 43 eyes with intermediate CNV, which corresponded to a sensitivity of 85%, a specificity of 84% and an accuracy (average of sensitivity and specificity) of 85%.

In the prospective phase of the study, enrollment was expanded to include patients from seven clinical sites in the United States; familiarity with a computer mouse was required. Of the 99 patients initially enrolled, 15 did not pass the training, eight had unreliable tests and 22 patients were excluded due to geographic atrophy, pattern dystrophy or poor-quality photographs.

In this portion of the study, abnormal test results were identified in 27 of 32 eyes with CNV and in three of 22 eyes with intermediate CNV, which corresponded to a sensitivity of 84%, a specificity of 86% and an accuracy of 85%.

In a subanalysis that examined whether size, type or location of the CNV lesion played a role in the sensitivity of the test, “there was a slight tendency of better sensitivity for classic, large or nonsubfoveal lesions,” but the differences were not statistically significant, the study authors wrote. The significance of this finding is that the test can identify early as well as late CNV lesions.

Potential use

In its current iteration, the home-based device, which is about 8 in. in height and weighs about 3 lbs., may be best suited for the indications studied — to remotely monitor patients who are at risk for developing severe disease (ie, development of CNV) that requires prompt treatment.

“I think that the device would be most beneficial for patients with non-neovascular AMD who are in need of monitoring,” Dr. Loewenstein said. “It would be most beneficial for patients with the dry form of the disease who have ocular high-risk characteristics of intermediate AMD and thus have high chances for developing neovascular AMD.”

For patients with advanced disease characterized by bilateral disciform scars, home monitoring may not be beneficial. However, Dr. Loewenstein said, studies are being performed to test the utility of the device in patients treated with an anti-VEGF regimen, either to signal a return of fluid on the macula or to prompt re-treatment.

“Small case series, which are in the process of being published, have shown that the device may track the response to treatment, the accumulation of subretinal fluid and need for re-treatment,” Dr. Loewenstein said. However, she added, “These are preliminary studies that need to be validated.”

A number of devices are currently in use in the home setting and are connected to a central database via a modem. Data that is constantly being streamed to Notal is monitored and analyzed to consider future improvements to the device. – by Bryan Bechtel

Reference:

• Loewenstein A, Ferencz JR, Lang Y, et al. Toward earlier detection of choroidal neovascularization secondary to age-related macular degeneration: multicenter evaluation of a preferential hyperacuity perimeter designed as a home device. Retina. 2010;30(7):1058-1064.

• Anat Loewenstein, MD, can be reached at Tel Aviv Sourasky Medical Center, Department of Ophthalmology, 6 Weizmann St., Tel Aviv, Israel 64239; e-mail: anatlow@tasmc.health.gov.il.