Optical coherence tomography (OCT) is an imaging technique regularly utilized by ophthalmologists to view multiple layers of the cornea and count the nerves and cells within. It’s important for diagnosing a variety of corneal conditions as well as when preparing for cataract surgery. The problem is that, as anyone who has tinkered with macro photography knows, it’s very difficult to obtain a sharp image of a large section of a curved surface such as the cornea. Now a team of collaborators in France has developed an exciting new OCT imaging technique that produces high resolution, in-focus images of substantial portions of the cornea. OCT relies on measuring the interference between light that passes through a sample, in this case the cornea, and a reference beam. The reference beam normally bounces back from a flat mirror, but the new technique, dubbed Curved-field OCT, instead uses a curved lens to essentially flatten the cornea so that more of it appears in focus. The result is that, compared to conventional OCT, sections ten times larger (> 1 square millimeter) can be viewed at high resolution. The cells and nerves appear clearly and can be readily counted. Since the entire scene is captured in one frame, the potential for aberrations is reduced. The developers of the new device say that it is ready for use in research and some planned features, such as automatic cell counting, will make it applicable for clinical practice as well. “As the curved outermost part of the eye, the cornea offers a transparent window into both ocular and general health conditions,” said corresponding study author Viacheslav Mazlin, from The Langevin Institute. “The cell-level resolution and large viewing area available from our instrument are ideal for monitoring corneal diseases like endothelial dysfunction and general diabetic conditions, understanding their evolution at the biological scale, and quantitatively evaluating the efficacy of novel treatment strategies.” Study in Optica: Curved-field optical coherence tomography: large-field imaging of human corneal cells and nerves Source
