Preferential Hyperacuity Perimetry® (PHP) is a patented technology developed by Notal Vision to detect minute vision changes when patients test with ForeseeHome.
Hyperacuity, or Vernier acuity, refers to the ability to perceive small differences in the relative location of two objects in space, beyond what is detectable with the better-known vision measurement, Snellen Visual Acuity (eg, 20/20). While Snellen visual acuity resolution is limited by the physical separation of photoreceptors (cones) in the macula, Vernier acuity includes cognitive processing of the stimuli by the brain to provide a 10-fold greater resolution than Snellen. For the patient, this means that vision changes too subtle to detect on their own are measurable.
In the ForeseeHome® AMD Monitoring Program, stimuli are successively displayed randomly across the central 14 degrees of the visual field. The stimulus consists of a series of dots, the majority of which are aligned with each other. A few dots are misaligned creating the perception of a wave or bump, an “artificial distortion,” in an otherwise straight line.
Each line with its artificial distortion is presented to the patient for 160 msec, while the patient focuses on a center dot. The test is termed preferential, as the patient perceives only the larger of two distortions when a competing, disease-related “wave” in the line is also present. By varying the size of the artificial distortions, the magnitude of the patient’s vision change can be quantified across the tested area and compared to their own baseline tests and to a normative population database. The brief presentation of each image ensures that cortical completion is not engaged and that fixation on a center dot is maintained during the testing. The presentation of the next stimulus is triggered when the patient moves the controlling mouse to the dot in the center of the screen.
The final term, perimetry, refers to the testing across an area. The area of the macula assessed with ForeseeHome is the central 14 degrees, or approximately XXXXXX mm2.
The Notal OCT Analyzer (NOA) is a computational image analysis algorithm designed to provide automated detection of pathological fluid in exudative retinal diseases including wet age-related macular degeneration, macular edema, and retinal vein occlusions. NOA uses a machine learning algorithm and image recognition computational technique to distinguish between normal morphologic structures and those associated with disease-related changes that occur as a result of fluid that is present under and within the retina.
With performance validated in a clinical trial that compared NOA’s sensitivity, specificity, and accuracy with that of 3 retinal specialists,1 the algorithm has multiple commercial applications including the analyses of data generated in patients’ homes with Notal Vision’s home-OCT device.
Optical coherence tomography (OCT) is a noninvasive, imaging technology widely adopted by eye care professionals in the early 2000s to view retinal anatomy and assess the need for treatment of increasingly prevalent and often age-related eye diseases that lead to blindness. Today, doctors utilize OCT devices to image retinal structures during scheduled office examinations, providing valuable diagnostic information.
The extension of disease management from the clinic to the home has the potential to address the undertreatment of retinal vascular diseases where fluid accumulates in and under the macula, the area of the retina that provides detailed vision. Patients with wet age-related macular degeneration, diabetic macular edema, and retina vein occlusions* require long-term, intensive ophthalmic care that includes frequent office visits and multiple intravitreal injections. Between office visits, patients can experience a recurrence of fluid, which is identified and treated at their next appointment. Monitoring at home for the presence of fluid can reduce the time from fluid recurrence to treatment by providing the doctor with an immediate notification of the change. Looking forward, the potential for longer-acting drugs, patient-administered therapies (eg, topical eye drops and subcutaneous drugs) and sustained-delivery implantable devices will offer physicians the opportunity to reduce the frequency of office visits while potentially maintaining treatment. Home-OCT will allow doctors to monitor the disease status of these patients continually, during the longer inter-visit intervals made possible with these products, reducing the time from a recurrence of fluid to the physician’s awareness of the change.
Notal Vision’s proprietary algorithm, NOA,† will analyze the OCT images generated at home on the Home-OCT device, and eye doctors will have online access to the testing results 24/7. The Notal Vision Independent Diagnostic Testing Facility (IDTF) will also provide notifications to doctors of changes in their patient’s testing results, similar to ForeseeHome.
*All exudative vascular retina diseases may be suitable for home-OCT diagnostics, including myopic choroidal retinopathy and post-surgical macular edema in high-risk patients.