It is difficult to say whether your son's optic nerve has been injured, but my suspicion is not, due to the physiology that I am about to explain. However, your son can see an ophthalmologist
, which is the type of doctor
that specializes in the eye, for an exam.
The eye is composed of many layers. Starting from front to back, the iris (circle that gives us our eye color) surrounds the pupil, which is a hole through which light passes. Light enters through the pupil and then travels through lens, which focuses the beam of light. Behind the lens is a layer of gelatinous, clear material called the vitreous humor. The vitreous is what fills out the eyeball to give it its shape. Finally, behind the vitreous humor is the retina, which is a very thin sheet of small nerve fibers that allow us to see light and color.
Within the retinal layer, there are some cells called "rods." The rods are responsible for letting us see light. When light hits the rods, a tiny portion of pigment falls off the rod for a short while; when the light disappears, the portion reattaches to the rod. While the tiny portion is detached, we become "blinded" by the light. It sounds like your son may have experienced this while he looked at the sun. However, after you stop looking at the light source, the rods should become normal after some time. If your son is having trouble seeing, he should be evaluated by an ophthalmologist.