Finally, coma is yet another aberration. In this case, the image magnification varies dramatically as the rays are far from perpendicular to the lens. The result is a ``comet'' pattern in the image plane. Another phenomenon is lens flare, in which rays from very bright light scatter through the lens and often show circular patterns. This is often seen in movies as the viewpoint passes by the sun or stars, and is sometimes added artificially.
All of the aberrations of this section complicate the system or degrade the experience in a VR headset; therefore, substantial engineering effort is spent on mitigating these problems.