You’ve probably seen old movies where sinking ships fire distress flares into the sky.

It’s a good way to attract help.

Researchers at the University of Michigan found a way to diagnose eye diseases using a similar concept.

They developed an instrument that causes retinal cells to glow when exposed to certain wavelengths of light.

Dying cells glow more brightly than healthy ones. And a large number of dying cells can indicate the presence of diseases such as glaucoma or diabetic retinopathy.

This kind of technology was used previously on animals, but until now it hasn’t been applied to human diseases.

A preliminary study on the instrument was published recently in the journal Archives of Ophthalmology.

The study involved six middle-aged women with a condition called pseudotumor cerebri (SOO-doe-too-murr suh-REE-bry).

The name literally means “false brain tumor.” It’s apparently caused by increased pressure in fluid surrounding the brain.

For some patients, it causes progressive, permanent vision loss.

Researchers used the instrument to check for dying retinal cells in both eyes of each patient.

The results showed the instrument detected vision loss as well or better than existing tests.

Researchers concluded that the instrument could become an important diagnostic tool.

So it may be just a few years before doctors can use it to catch eye diseases in their earliest stages, before they’ve begun to diminish vision.

If that happens, those distress signals sent out by dying cells could be answered, maybe in time to save patients’ eyesight.