Products specially designed for the challenges of Tunnel Vision
Disorders including Retinitis Pigmentosa (RP), Choroideremia, and late-stage glaucoma cause reductions in peripheral vision (tunnel vision) and also reduces the ability to see at night and in dimly lit locations. Our peripheral vision helps us to walk safely and to detect movement in our side vision. Individuals with reduced peripheral vision may bump into obstacles while walking and have difficulty locating items in their environment. This is particularly a challenge when navigating stairs and avoiding collisions with people.
Reversed telescopes (usually a 2.2x power) have traditionally been offered as an optical treatment option for the narrow field of view. The rationale for these reversed telescopes is that they reduce the image size by 50%, doubling the field of view diameter and allowing more visual information to be visible within the restricted visual field.
For instance, an individual with a 10-degree diameter field of view, when looking through a 2.2x reversed telescope (or 0.5x in field expansion terminology), will have the equivalent of a 20-degree field of view, a doubling of the visual field diameter.
A simulation that demonstrates how image minification can help tunnel vision..
Ocutech's reversed telescopes called Field Expanders (FE) and Image Minifiers (IM) are specifically designed for the treatment of restricted visual fields. They provide a flat (undistorted) field of view, providing a much more natural visual perception for the user.
When traditional distance vision telescopes are reversed to produce image minification they also distort the image making it appear rounded and tilted (barrel distortion), which is especially noticeable when looking downward for walking. The distorted image can reduce the device’s benefit for safe mobility, a major goal of the device.
