Elner and his colleagues then used their new metabolic imaging system to check the health of cells in the women's eyes by shining a blue light on their retinas and looking for green fluorescence given off by oxidized proteins in dying cells. They measured the intensity of this fluorescence and found that it was significantly greater--60 percent, on average--in the eye that was most affected by the disorder. There was no significant difference between the measurements in the eyes of women without PTC. "Diseases seldom affect both eyes the same," Elner says. "We generally pick up an asymmetry in all kinds of diseases."

The new technique proved as effective as, or often superior to, the standard tests performed on the women. Elner and his colleagues are also studying the method in patients with glaucoma, which damages the optic nerve, and diabetic retinopathy, which involves changes in the blood vessels in the retina, but they have not yet published the results of those studies.

"This technique is intriguing," says Sunil Srivastava, an assistant professor of ophthalmology at Emory University's Eye Center, who was not involved in the work. "There's a lot of potential for it." But, he says, "what's needed is going to be lots of data looking at patients with early disease, and following them with it."

Because the new imaging system could be used to track metabolic changes in the cells of the eye, Elner believes that it may also be useful in drug discovery. The effects of potential treatments could be tracked over weeks, he says, rather than having to wait months to observe changes in vision, or in the structure of the eye.

"This will be a faster method of screening for drugs," Elner says.

It could also enable physicians to closely monitor the effect of drug regimes on their patients, he adds, so that they can figure out the very best treatment strategy.