Color anomaly (a. colorum) is a rare optical phenomenon in which multi-colored halos or spots appear around bright light sources (sun, moon, lanterns, etc.). This is due to the refraction of light in the eye lens.
Typically, the anomaly appears as concentric rings around the light source. The colors of the rings can vary from red and orange near the center to blue and purple at the edges. Sometimes there is an iridescence effect, when the colors shimmer, like on a soap bubble.
The causes of color anomalies can be different. Most often this is due to disturbances in the refraction of light in the lens due to its clouding or deformation. Also the cause may be astigmatism, cataracts, diabetes, migraine. In some cases, this is normal and does not require treatment.
People with a color anomaly see the world a little differently. To them, the sun, moon and light sources appear surrounded by multi-colored halos. This is an interesting, but quite rare phenomenon.