A novel assistive device may have the ability to restore significant vision to a population previously resigned to the debilitating effects of low vision.
Toronto-For the nearly 2 million U.S. patients living with low vision, even the simplest of daily tasks can be complicated, causing isolation and dependence.
As the population ages, and with various degenerative eye diseases and those caused by comorbid conditions-such as diabetes-on the rise,1 this figure is projected to grow to nearly 5 million by 2030.2
Medical and surgical interventions are often incapable of helping people with such vision loss, leaving them to rely on technological aids that, for years, have provided only marginal improvements.
Enter hands-free, mobile eyewear technology (eSight Eyewear, eSight Corp.)
Specifically designed to support people with low vision, the assistive device allows users to move seamlessly between activities, including those that would otherwise be inaccessible with vision loss.
Nearly any patient with macular problems-such as age-related macular disease or diabetic retinopathy-can benefit. However, the eyewear is less predictable with retinitis pigmentosa and glaucoma.
The eyewear uses a high-resolution camera and two organic light-emitting diode (OLED) displays positioned near the eye and displays a sizable 30° horizontal field of view.
With the image so close to the eye, focusing requires advanced optics and image processing. Specifically designed contrast and stabilization algorithms processed through a proprietary operating system produce an image and filter it through optical prisms situated between the patient’s distance prescription lenses and the OLED displays.
The images perceived by the users are much better than what they can see normally, resulting in significant gains in acuity and contrast sensitivity. Many users have reported that their central blind spots-if present-shrink or disappear altogether. The images are presented at latency below 100 ms (despite intensive CPU use), which is critical to preventing vertigo and nausea.
To achieve high-resolution imagery in the 30° horizontal field, the eyewear utilizes an unusual aspherical prism design. With an aspherical lens, bending light cannot be done with the normal curved surface, primarily due to space constraints.
The typical spectacle lens is a spherical prism where the curvature of the prism follows the arc of the circle. However, the assistive-device prism has a non-uniform shape that does not follow an easily defined equation, such as a parabola or eclipse. Although the active surfaces reflecting light are not following a circular radius, they must still produce the correct image after reflecting five to six times before passing through the prescription lenses into the eye.
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Users also have real-time control over certain parameters of the image that can provide context specific enhancements that are essential in a low vision application. Users manipulate brightness, zoom control, freeze and save images, and adjust contrast and focus with the touch of a button on the small, external controller that also houses the processing unit and the battery. The zoom range is up to 14 times-a practical limit to control shakiness associated with a camera worn on the head.
With the collaboration of focus groups, early users, and various experts, the developer offers a highly intuitive user-interface design that works well for the legally blind, elderly, those lacking computer skills, and individuals with dexterity issues.
Manipulating dropdown menus and other features requires effort for legally blind persons, so the device tends to work with tactile controls that users can navigate by touch, without reference to visual menus.
Additionally, a patented electronic headset swivels up and down on a mounting frame to allow for either near immersive or bioptic viewing.
In the down position, users look right into the display for maximum vision enhancement, but have limited use of peripheral vision. When bioptically tilted, users can glance up to see the display, but can fully engage peripheral vision and see the horizon with natural vision.
This feature is attractive because people with central vision loss often have excellent peripheral vision, which means that the device preserves the best aspects of natural sight while enhancing parts of vision that are compromised.
The majority of users operate the eyewear in bioptic mode 90% of the time when ambulating and will glance up when they need enhanced vision.Customization
The customized device is not transferable from one user to another. A user’s distance vision prescription is integrated directly into the hardware; the displays must be properly oriented and lined up on the user’s pupil; and the mounting system and nose bridge must be adjusted to take excessive weight off the nose and make the device comfortable.
Every new user has the opportunity to participate in a training program supported by the company’s experienced ambassadors that produce proficient users in days. Optionally, some users may also opt to undergo low vision rehabilitation to train on the device.
The nonsurgical device has the ability to restore significant vision to a population previously resigned to the debilitating effects of low vision. Patients suffering with macular problems will benefit from this portable, easy-to-use system that enables them to conduct routine activities without difficulty and participate in the world around them.
1. American Diabetes Association. Statistics about diabetes from the National Diabetes Statistics Report, 2014. American Diabetes Association. http://www.diabetes.org/diabetes-basics/statistics/?referrer=https://www.google.com/. Published June 10, 2014. Accessed Sept. 3, 2015.
2. Department of Health and Human Services and National Institutes of Health. Low Vision. National Eye Institute. https://nei.nih.gov/eyedata/lowvision. Revised Sept. 2012. Accessed Sept. 15, 2015.