New Technology Helps Detect Retinal Diseases

At the annual meeting for the Association for Research in Vision and Ophthalmology, held at the University of California, San Diego (UCSD), Microvision, Inc. presented first year results of an ongoing study to detect retinal diseases and vision disorders using an Entoptic Perimetry Self-Test Workstation. The new workstation combines entoptic perimetry techniques and software developed at UCSD with Microvision's Virtual Retinal Display (VRD) technology. Under a confidential arrangement, Microvision loaned the UCSD group a portable retinal scanning display system to perform the studies.

The goal of the program was to discover a noninvasive and highly accurate way to detect retinal diseases. Microvision's VRD solution provided the answer. Patients looked directly into Microvision's device, which scanned the entoptic perimetry stimulus onto the patient's retina. Patients without retinal damage saw moving particles throughout their field of vision. However, patients with areas of retinal damage were actually able to paradoxically see their own blind areas and localize them. Using a pen-based computer program, patients were asked to trace the borders of any visual disturbances, in effect, creating a digital map of their own retina, which accurately detailed the locations of damaged tissue. These images were then compared with the "gold standard" -- photographs taken from a fundus camera with outstanding results.

The device was shown to allow rapid and accurate retinal screening superior to traditional methods, such as the Amsler grid, much more rapidly and conveniently than computerized visual field perimetry. The self-administered test took less than one minute, and showed statistically significant results of 93% sensitivity and 100% specificity for the patient to locate scotomas (blind areas) due to retinal damage within the central 120 degrees diameter of vision. During the last year, clinicians at the Shiley Institute performed entoptic perimetry screening tests on 58 patients with a variety of retinal diseases including AIDS-related CMV retinitis, diabetic retinopathy, ocular melanoma (the most common eye cancer), blood vessel disorders, retinal detachment, macular hole, age-related and macular degeneration.

"This is the first study which demonstrates that VRD-based entoptic perimetry can be used to screen for retinal damage in asymptomatic patients within virtually all of the visually significant retina," said Dr. William Freeman, professor of ophthalmology and administrative director of the retina service at the UCSD Shiley Eye Center. "This rapid, noninvasive 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."

"The device offers a rapid, compact, and easy-to-use test that does not require a skilled technician," stated Daniel J. Plummer, PhD, assistant research scientist and principal investigator of the studies. "The VRD-based system also benefits the patient because patients with poor central visual acuity required no corrective eyewear to view the stimulus," Plummer stated. "This shows that patients with vision complaints or diseases that may affect vision can have the test performed even without proper eyeglass correction."

Headquartered in Bothell, WA, Microvision, Inc. is the developer of the patented VRD technology that uses a rapidly scanned beam of light to project images on the eye's retina, allowing the viewer to see large, full-motion images without the need for a conventional display screen.