The cornea is a convex spherical mirror. Hence, the corneal light reflex is an erect virtual image at the principal focus of the sphere. The corneal light reflex is a misnomer because it is subcorneal in position and is 3 to 4 mm behind the anterior surface of the cornea. It is technically a reflection. Rotation of a mirror on its edge, or vertical axis, produces a displacement of the lighted image similar to that which one would expect with displacement of the image by a prism. Such a reflex image can be restored to a neutral position by corrective prism. Moreover, the visual axis, which is bent through rotation of the mirror, is also apparently rectified by such prism.
A look at the past. . .. Arch Ophthalmol. 2007;125(7):996. doi:10.1001/archopht.125.7.996