Optical coherence tomography is how an eye doctor sees beneath the surface of the retina.
It works similarly to an ultrasound with light, building a cross-section of the tissue layer by layer, and it is the standard way to catch diabetic retinal damage and glaucoma early.
The machines that do it are large, expensive and installed in hospitals.
A patient in a small town who needs one has to travel to a city, a journey many people do not make until their sight has worsened.
was set up to shrink the machine.
