When a person is looking at lights and a colored halo appears around the light, it is medically called ‘iridopsia’. The appearance of iris in front of the eye is due to the spectroscopic effect of the change in the refractive power of the eye, which breaks down the white light coming from the front into multiple color components depending on the wavelengths of the various lights it contains, thus giving rise to the typical colored halo. Like a rainbow after a rainstorm, it is arranged in a sequence of green inside and red outside. Iris is a common symptom in eye diseases and is often a sign of the following eye diseases: 1. Conjunctivitis As mucus secretions coat the surface of the cornea, iris can appear and disappear after the secretions are wiped away. If there is blood, pus or small air bubbles in the outer conjunctival sac, iris can also appear. 2, keratitis After keratitis occurs, damage to the corneal epithelium and corneal edema can lead to iridopia. 3, uveitis Due to inflammation involving corneal endothelial cells, which disrupts corneal hydration, can cause corneal epithelial edema, such as the appearance of large bubble-like or small bubble-like, uveitis can have iridopia symptoms. 4, cataracts These patients will have iridopsia due to water absorption and swelling of the radially arranged crystal fibers, which will produce spectrophotometric effects. 5. Glaucoma The elevated intraocular pressure in patients causes corneal epithelial edema and fluid retention between cells, which changes the normal refractive state of the cornea and can lead to iridopsia. Therefore, iridopia is often a precursor to a variety of eye diseases, and once it occurs, it should be promptly examined by a doctor to find the true cause and then treated.