When a person is looking at lights, if there is a colored halo around the lights, it is medically called “iris vision”. The so-called colored halos are also known as colored halos. This is due to a change in the refractive index of the eye, which breaks down the white light coming from the front into multiple color components depending on the wavelength of the light it contains, resulting in a typical colored halo. Iridescence is a common symptom in eye diseases. To distinguish between physiologic and pathologic iridopia, the patient can be asked to view a light source through a narrow slit that is placed vertically and moved in front of the pupil; in the case of physiologic lens iridopia, the iridopia is only partially visible during the movement of the slit and its position changes with the movement of the slit piece. When the fissure is located at the pupillary margin, the horizontal radial fibers of the lens refract, so a transverse colored arc is visible above and below, and when the fissure is located in the center of the pupil, the vertical fibers of the lens refract, so a longitudinal colored arc is visible on each side of the horizontal direction, while when the fissure is located between the pupillary margin and the center of the pupil, the oblique fibers of the lens refract, so a longitudinal arc can be seen in the upper right, lower right, upper left, and lower left directions. When the slit is located between the pupillary margin and the pupillary center, the oblique fibers of the lens play a refractive role, and a short oblique color arc can be seen in the upper right, lower right, upper left and lower left directions. When the slit slice is removed, iridophoria returns to a round shape. In the case of pathological iridopsia, the color ring remains round during the movement of the slit slice, but the color is only slightly darker. In addition, the iris can also be found in normal people when viewing small, bright streetlights in fog, because there is more moisture in the air, which is the same as the rainbow that appears after a rain shower.