Optic Nerve In Eye
Did you ever wonder what the nerve inside your eye looks like?
You can see a small circular yellow image in the middle of the streak of light in this picture to the left. That is where the optic nerve is entering the eye. Before it enters the eye it is covered with myelin. Myelin acts like the insulation on a wire and speeds the transmission of the signals from the photo-sensitive cells inside the eye to the back of the brain. Myelin is fairly opaque so it stops as the nerve fibers travel to the interior of the eye. The nerves are arranged in front of the rods and cones and would interfere with vision if they maintained the opacity.
The optic nerve is about 1.5 mm in diameter and carries approximately 1.2 million separate fibers. Imagine trying to connect a wire with over a million strands. The nerve itself creates a small circular blind spot where it penetrates the eye. While your eye doctor can measure this with a visual field testing instrument, the brain completely filters it out. That is fortunate since otherwise everyone would constantly see a dark hole in their vision.
Your Optometrist Can Detect Many Health Problems From Your Eye Exam
The nerve becomes elevated and swollen in some eye diseases and with some tumors of the brain. This can be seen on an eye examination when eyes are dilated. There are blood vessels that accompany the nerve into the eye. The blood vessels provide a view of the health of the entire body. Health problems like high blood pressure create changes in the blood vessels of the eyes that can be detected in vision examinations.
Eyes Are Remarkable!
It is remarkable when you connect a small nerve under 2 millimeters in size to the incredibly extensive world of vision and perceptions that we inhabit.