Low vision rehabilitation is the only proven way to restore functional vision and maintain a high quality of life in patients with permanent vision impairment. Low vision aids are devices that manipulate visual information, for example, magnify images, to compensate for impaired vision. The patient's willingness to accept a low vision aid, ability to adapt to it and the motivation to use it persistently are the key factors fo successful low vision rehabilitation. Wearable magnifiers (bioptic telescopes, BT) are devices that have the potential to benefit patients with central vision loss (CVL) in many important daily living tasks. However, current optical and electronic wearable magnifiers suffer from very low prescription rates and are used only in a few tasks because only a few clinicians master the complicated prescribing and fitting procedures and because patients having difficulties accepting the appearance of the devices and learning to adapt to their unnatural way of seeing. Holographic Waveguide Display (HWD) technology uses thin holographic couplers to guide signals from an image source to the eye via a piece of glass substrate. A HWD-based wearable magnifier may overcome many of the difficulties of the conventional wearable magnifiers because of its compact design in front of the eye, light weight, low cost and flexibility in accommodating the wide variety of needs of CVL patients. The proposed research explores the feasibility of applying HWD technology to low vision aid through 3 specific aims: 1) to develop a wearable Holographic Waveguide LOw Vision Eyewear (HW-LOVE) prototype; 2) to compare the relative effectiveness of the HW-LOVE prototype and conventional BTs in improving impaired vision by conducting a 2-period, 2-sequence crossover study on 22 CVL patients. Office vision tasks such as visual acuity and contrast sensitivity and real-life visual tasks such as face identification, facial expression recognition and traffic sign recognition will be performe by the CVL subjects with the naked eye, conventional BTs and the HW-LOVE prototype; 3) to assess low vision subjects' preference to the HW-LOVE or conventional BTs in their appearance, weight, comfort of wearing, field of view, acuity, brightness and so on using a user preference questionnaire. If Phase I research demonstrates that the HW-LOVE is useful in aiding CVL patients and that CVL patients prefer the HW-LOVE over conventional BTs, Phase II R&D will be focused on improving wearability and display quality of the HW-LOVE, on developing prescription, fitting and dispensing support systems for clinicians and on longitudinal clinical trials to assess patient acceptance, adaptation, utilization and preference of the HW-LOVE in CVL patients. The estimated hardware cost of the prototype is in the range of $1,500. The target cost of a commercial product should be <$1,000.
Wearable magnifiers are powerful low vision aids that have the potential to enable patients with central vision loss to perform many important daily living tasks but current wearable magnifiers also suffer from very low prescript rate and limited usage because of their odd appearance and unnatural way of use. This research explores the feasibility to apply a new imaging and display technology to low vision aid by developing a prototype eyewear that can display magnified images to low vision patients while featuring the inconspicuous appearance of a normal eyewear, light weight and natural way of use.
