For the past six years, Microvision Inc. has been developing its virtual-retinal-display (VRD) technology for specific market niches such as the design of head-mounted displays for military and aerospace applications. Recently however, VRD activity has been heating up in the medical realm. Last May, at the annual meeting of the Association for Research in Vision and Ophthalmology, the faculty of the Shiley Eye Center, Department of Ophthalmology, School of Medicine at the University of California, San Diego (UCSD), presented the results of an ongoing, year-old study of non-invasive VRD-based entoptic perimetry for diagnosing retinal disease. The VRD scans a beam of light from a remote light source across the retina of the patient's eye. People with areas of retinal damage are able to paradoxically see and localize their own blind spots.
Under a confidential arrangement, Microvision loaned the UCSD group a portable retinal scanning display system to perform the research. The major goal of the programme consisted in discovering a non-invasive and highly accurate way to detect retinal diseases. Patients have to look directly into the device, which scans the entoptic perimetry stimulus onto the retina. People without retinal damage see moving particles throughout their field of vision. However, patients with areas of retinal damage are actually able to digitally map in detail the regions of damaged tissue. A pen-based computer programme allows them to trace all the borders of visual disturbances. The resulting images are compared with the "gold standard", which are photographs taken from a fundus camera with outstanding results. The fundus camera captures images of the internal surfaces of hollow organs like the eye.
The VRD-based workstation can screen for retinal damage in asymptomatic patients within virtually all of the visually significant retina, as Dr. William Freeman, professor of ophthalmology and administrative director of the retina service at Shiley, reported at the meeting. The device enables rapid and accurate retinal screening superior to traditional methods, such as the Amsler grid and much more conveniently than computerized visual field perimetry. The self-administered test takes less than one minute, showing statistically significant results of a 93% sensitivity and a 100% specificity for the patient to locate scotomas or blind areas due to retinal damage within the central 120 degrees diameter of vision. The Entoptic Perimetry Self-Test Workstation combines entoptic perimetry techniques and software designed at UCSD with Microvision's Virtual Retinal Display (VRD) technology.
During the last year, clinicians at the Shiley Institute performed entoptic perimetry screening tests on 58 patients with a variety of retinal diseases, like AIDS-related CMV retinitis, diabetic retinopathy, ocular melanoma which constitutes the most common eye cancer, blood vessel disorders, retinal detachment, macular hole, age-related and macular degeneration. The non-invasive screening test has the potential to be an excellent addition to the clinical tool set of primary-care health providers to rapidly screen for retinal damage and diseases. It will also allow for community screening of underserved populations to detect vision loss, according to Dr. Freeman. The VRD-based system bypasses the lensing system and directly stimulates individual retinal neurons. As a result, it also benefits patients with poor central visual acuity since they do not require any corrective eyewear to view the stimulus, as principal investigator Dr. Plummer stated.
Microvision's Virtual Retinal Display coupled with the UCSD group's entoptic stimulus software and clinical data base provides the potential for a new product that can make eye diagnostics a more accessible, effective and affordable part of health care. The market opportunity for such a product is significant. Rick Rutkowski, Microvision President & CEO, estimates that there are over 150.000 primary care physicians, serving the potential of over 30 million individuals, requiring continual screening for a range of common eye diseases, who are prime targets for a VRD-based perimetry product. The company is currently marketing the VRD technology to prospective eye care and diagnostic companies and seeks ways to secure partnerships in order to bring the entoptic perimetry product to market.
The UCSD Shiley Eye Center is a patient care and research institution which is part of the University of California San Diego system. The crafting of the self-administered diagnostic tool, referred to as the Entoptic Perimetry Self-Test Workstation, from the clinical perspective, and the patient testing was performed by a group, led by Dr. William Freeman, who is retina surgeon and professor of ophthalmology. The team started in 1994 and consists of Dr. Daniel J. Plummer, visual psychophysicist and research scientist and Dr. Dirk-Uwe Bartch, an optical engineer and assistant professor. A portion of the UCSD group's research funding was provided by the U.S. National Eye Institute of the National Institute of Health as well as other sources. More information can be found at the Shiley Eye Center Retina Web site.