Eye exams may be getting quicker and easier, plus ophthalmologists may be able to save money on equipment, thanks to a new instrument developed by scientists in Poland and Spain. Unlike existing eye-examining technology, it allows the entire eye (from front to back) to be imaged via a single lens.

Ordinarily, ophthalmologists have to switch between multiple lenses throughout the course of an exam. This is because each lens has a fixed focal length of only a few millimeters – the lens that can focus on the cornea can't also focus on the retina, and vice-versa.

That's where the new optical coherence tomography (OCT) imaging system comes in, with its electrically tunable lens.

At the heart of it is a container filled with a clear optical fluid, sealed with a transparent polymer membrane on the front – that membrane is the lens, and it can incrementally change shape. When an electrical current is applied, the membrane gets pushed down into the container by a ring-shaped structure, causing it to bulge against the fluid. When the current ceases and the membrane moves back up, the convex bulge becomes a concave bowl.

In tests performed on seven healthy test subjects, the system was able to not only image the front and back of the eye, but it could also image the interfaces of the eye's vitreous gel with the retina and lens with "unprecedented detail."

The research was led by Ireneusz Grulkowski of Poland's Nicolaus Copernicus University, along with Pablo Artal from Spain's Universidad de Murcia. It's described in a paper that was recently published in the journal Optica.