As many as 5 percent of children suffer from amblyopia, or "lazy eye, "which causes an otherwise normal eye to lose proper vision. Often the result of a misalignment of the eyes, lazy eye is treatable if caught early-but diagnosis is trickier in children too young to read an eye chart. So Johns Hopkins pediatric ophthalmologist David Hunter and his colleagues have built a device to check eye alignment automatically.

The device, still in early testing, shines a polarized infrared beam into a patient's eyes and analyzes the light coming back to detectors. When the beam reflects off the fovea-a small, specialized area of the retina responsible for high-acuity vision-it has a characteristic signature. By looking for this signature, Hunter says, the device can tell when an eye that should be aimed straight at the light is more than one degree off the mark. Hunter's team is working on a second-generation prototype and looking for a commercial partner to help develop the device.