Space optics technology in the 1980s has been adapted to help children see more clearly. Collaborating with research ophthalmologists and optometrists, scientists Joe Kerr and the late John Richardson of NASA’s Marshall Space Flight Center in Huntsville, AL, adapted optics technology for eye screening methods using a process called photorefraction. Photo - refraction consists of delivering a light beam into the eyes, where it bends in the ocular media, hits the retina, and then reflects as an image back to a camera. A series of refinements and formal clinical studies followed their highly successful initial tests in the 1980s.

Evaluating over 5,000 subjects in field tests, Kerr and Richardson used a camera system prototype with a specifically angled telephoto lens and flash to photograph a subject’s eye. They then analyzed the image, the cornea, and the pupil, in particular, for irregular reflective patterns. Early tests of the system with 1,657 Alabama children revealed that, while only 111 failed the traditional chart test, Kerr and Richardson’s screening system found 507 abnormalities.

In 1991, NASA transferred the exclusive license for the system to Vision Research Corporation (VRC) of Birmingham, AL, after Kerr sold his company to VRC. Also in 1991, VRC began a two-pronged marketing effort for the VisiScreen Ocular Screening System-Clinical (OSS-C): sales to pediatricians and family practitioners, and the widespread distribution of screening services to school systems and other organizations with large numbers of children.

How it Works

Using photorefraction, VRC’s VisiScreen photographs a patient’s eyes at a specific distance and angle. Light enters the eye, reflects off the retina, and returns an image to the screening system. Specialists at VRC later analyze the images and issue a report to the family or physician, indicating areas of possible concern.

Shown here, anisometropia is a condition in which a patient’s eyes have unequal refractive power. If not caught early enough, anisometropia can cause amblyopia, or lazy eye. VRC’s screening program has found over 3,000 children with indications of anisometropia.

Although not intended to replace examination by an eyecare professional, VisiScreen can highlight possible problems that a child’s parents and teachers may not have noticed. The system can detect common childhood vision problems including myopia (nearsightedness), hyperopia (farsightedness), astigmatism (corneal irregularities), strabismus (alignment errors), and cataracts, which occur in roughly 1 in every 1,000 infants.

VisiScreen tests the eye for refractive error and obstruction in the cornea or lens. The photorefractor analyzes the retinal reflexes generated by the subject’s response to the flash. If the eye is properly focusing the light, as happens in a child with normal vision, a smooth, clear “red eye” image of the retina reflects evenly from the pupils. For a child who is hyperopic, a bright half-moon reflects from the top of the pupil. In the case of myopia, a crescent in the bottom half of the eye reflects more brightly than the top. Similarly, other potential problem areas reflect differently than a properly focused eye would.

The system provides several major advantages over traditional vision screening with letter or picture charts: children do not need to respond during the test, so anyone, including an infant, can be screened regardless of age or verbal ability; and the process is also as quick as taking a photograph, so screeners can process large numbers of patients rapidly.

Commonly known as “lazy eye,” amblyopia can cause permanent vision loss in the weaker eye if not detected and corrected early enough. Since its inception, VisiScreen has found amblyopic factors in over 70,000 children, or approximately 1 child in 40. If children are not treated before age 6 or 7, they may suffer permanent vision loss. In addition, amblyopia leads to 17 percent of all adult total blindness. Although blindness is not a concern for most children in the screenings, limited vision can affect both social and educational development. A child who cannot see well is at an obvious disadvantage in the classroom, and those who fall behind early in their education are more likely to have additional problems later.

Where it Stands

In 1991, the Russell Corporation (Alexander City, AL) joined forces with VRC to conduct a large-scale eye-screening program in Russell’s employee daycare centers. In approximately 10 percent of the children, the program identified previously unsuspected vision problems significant enough to warrant follow-up examination by an eyecare professional. Because several eye conditions can worsen and even cause blindness if not caught early, there were clear benefits in continuing the screenings.

The success of this program led Russell Corporation to collaborate with Alabama Power and the Alabama State Department of Education to sponsor a program for all kindergarten students in the state. VRC also contributed to the growth of the nonprofit organization, Sight Savers of Alabama, to provide vision care and assistance to needy children. VRC has since used VisiScreen to check more than three million children in schools and daycare centers.

Pediatricians and family doctors in over 20 states use VisiScreen to identify possible vision problems in children, who are then referred to ophthalmologists and optometrists for diagnosis and treatment. VRC screened approximately 150,000 Alabama elementary school students during the 2007-2008 school year, and continues to offer its services across the Southeast. Over 3,000 children had indications of a difference in the power of the eyes called anisometropia, which can indicate or lead to amblyopia.

Through the efforts of VRC and VisiScreen, NASA has improved the lives of hundreds of thousands of children whose eye problems may have remained undiagnosed or otherwise untreated. VRC is planning more improvements and enhancements to VisiScreen, and soon will begin field-testing a new generation of the screening system.

More Information

For more information on Vision Research Corp.’s VisiScreen system, visit http://info.hotims.com/22926-180. Learn about other NASA spinoff technologies at www.techbriefs.com/spinoff.