New this year, we’re introducing a new, educational blog series called “How Things Work,” and through it we will be covering the various and wonderful workings of the human eye and vision system. First up, we have the Optic Nerve.

How, exactly, do we see? Well, that’s a complicated question with a complicated answer. They human eye is one of the most complex and wondrous organs in our bodies, and we will continue to explore the visual system in more detail with each new issue in this series.

In the early embryonic stages of development, the eyes develop as a direct neurological extension of the brain. How we perceive the world around us, in simple terms, is a direct result of light passing into our eyes through the lens, and then that visual information is transmitted directly through the optic nerve to the brain itself. There, the brain determines what do to next based on what you have just “seen.” From end to end, the visual system really is quite remarkable. It’s why we love what we do!


The optical nerve is located at the back of the eye, and it is directly tied into your body’s central nervous system. It’s made of ganglionic cells (nerve cells) which transmit what you see to the brain via electrical impulses. The optic nerve contains over 1 million nerve fibers, carrying an extraordinary amount of information from the visual system to the brain’s central nervous system. This information enables us to be aware of our surroundings, determine friend from foe, pickup on subtle movements in our peripheral vision, and even detect subtle cues in the light our eyes process to help regulate our internal circadian rhythms.

January is Glaucoma Awareness Month, and we would be remiss if we didn’t mention the fact that Glaucoma leaves millions blind as a direct result of it’s effect on the optic nerve. The visual system relies on the safe transport of visual information from the eyes to the brain. With the increase in ocular pressure caused by glaucoma (an increase in ocular pressure due to increased fluid in the eyes), the delicate eye tissues can no longer perform their intended functions. This higher pressure can also cause irreversible damage to the optic nerve itself, permanently affecting your vision in the process. This pressure compresses the optic nerve fibers, causing cell damage and death (optic nerve atrophy), and once it happens it cannot be repaired.

That’s why it’s so important to see your eye doctor annually. Without revealing itself through symptoms you can notice, glaucoma is a silent thief of sight. During your comprehensive eye health examination, your Primary Eyecare optometrist can help to diagnose and treat glaucoma in its various stages.

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