Researchers at Germany's University of Tübingen recently published a revolutionary paper on the nature of rod photoreceptors. This new research suggests that rods play a significant role in vision even during daylight hours.
Since rods can't distinguish color, most ophthalmologists assumed they played little to no role in vision during daylight. Eye doctors argued that cone photoreceptors are more important for healthy vision under strong light. However, researchers involved in this study found that rods were active in the eyes of mice even as light increased in the lab.
Dr. Thomas Münch, who teaches at the Werner Reichardt Centre for Integrative Neuroscience of the University of Tübingen, led a group of Finnish, English, and German researchers in this examination. Shockingly, researchers found that the rod activity in their mice's eyes only grew as they increased the lighting.
Rods and cones are the two major photoreceptors in the retina. While both of these cells are responsible for transforming light waves into electrical signals, rods are thought to be active only in dark areas, whereas cones are active under brighter conditions. These definitions of rods and cones are still extremely common in mainstream medical literature.
The mice used in the first part of this study had no cones in their retinas. Scientists noted that they could easily see numerous rod signals both in the mice's eyes and brain scans. Taking this study a step further, researchers noted that rods even increased in mice with functional cones under high-intensity lights.
Obviously, this research changes the standard medical assumption that rods are only active during the nighttime or in dimly lit rooms. In the official report, Münch notes that this finding could "open new avenues towards treatments for patients without functional cones, so-called rod monochromats."
Most eye doctors researching photoreceptor disorders have been more interested in cones in recent years. Since more people are staring at harsh artificial lights nowadays, ophthalmologists have placed far more importance on healing cones rather than understanding or treating rods.
Münch and his colleagues hope their study will encourage eye doctors to better understand the nuances of rod function in the retina. He also hopes this data will encourage new research into rod-based treatments for numerous visual disorders.
People who are affected by rod monochromacy have no functioning cones, which means they cannot distinguish colors at all. Although extremely rare (about one in every 30,000 people are rod monochromats), this disorder can significantly reduce a person's quality of life.
While most of the scientists involved in this study work at the University of Tübingen, professors from the University of Manchester and the University of Helsinki also participated in this research. Besides Dr. Münch, a few other key researchers on this study include Doctors Alexandra Tikidji-Hamburyan, Riccardo Storchi, and Johannes Dietter.
Anyone who wants to read more about this fascinating study should pick up the latest copy of Nature Communications. Study authors entitled this article, "Rods progressively escape saturation to drive visual responses in daylight conditions."