Have you ever wondered how our eyes can see? How we can comprehend faces, objects, and colors.
I hope we never take how lucky we are to observe the world around us for granted—the breathtaking view of a cold, crisp morning that has magically turned into a winter wonderland overnight. The way the sky is lit softly with vibrant yet calm, muted colors in the evening. Or the ability to look into the eyes of our loved ones. What a gift eyesight is.
Anatomy and Physiology of the eye
Neuroscientist Andrew Huberman states that our eyes are initially pieces of brain matter not encapsulated in our skull; instead, the brain matter squeezes into our eye sockets. The eyes collect information with light and send this information to the brain. The eyes have photoreceptors, which include your cones and rods. Cones are mainly responsible for vision in lighted areas, and rods are primarily for dark or low-light areas. Light enters through the pupils, and the lens focuses the light on the retina.
This part is so cool. When the retina receives this light, photoreceptors (cones and rods) have a chemical reaction involving vitamin A that converts this information from light to electrical information. This translated electricity is messaged to the brain using neurons called retinal ganglion cells.
What we see is not the exact replication of what we are looking at. Instead, it is what our brain perceives based on the wavelength of the light coming off of the object in our line of vision. How fascinating? I am sure you learned about “Roy G BIV” at some point in school. Also known as the visible light spectrum, “Roy G Biv” is a pneumonic to remember the order red, orange, yellow, green, blue, indigo, and violet. These are the colors we see based on their wavelength. The highest wavelength to the lowest goes from red to violet. The visible light spectrum is how we perceive color.
Protective Mechanisms
The body has many protective mechanisms. Our eyelashes and eyelids shield our eyes. There is a reflex that occurs when a threat comes near our cornea. This reflex is called the corneal reflex, and it causes us to blink to protect our eyes from harm. Your trigeminal nerve and facial nerve trigger it. The trigeminal is a sensory nerve. It is the fifth cranial nerve. It comprises three nerves: your ophthalmic, maxillary, and mandibular.
I remembered these in nursing school and still do, by thinking TRI-geminal, tri means three. So, you can put up three fingers and lay them on your cheek horizontally. They will fall on your mandible, maxilla, and near your eye, a.k .a. ophthalmic. The facial nerve is a motor nerve. It is the seventh cranial nerve. Its function is exactly as it sounds, for facial expression and movement. Can you believe all the nerves and processes that have to take place to blink? We blink subconsciously all day.
Accommodation
Have you ever gotten up in the middle of the night to find your way to the bathroom? After stubbing your toe on the bed and bumping into more objects than you thought you had in your path, you finally make it to the light switch. As the abrasive light blinds you, your eyes acclimate to see in the brightness. Then, as you make your way back to the bed, you can’t see anything and hope you end up safely under the covers.
All of this has to do with accommodation. Your eyes do this by the pupil dilating or constricting based upon the distance you look at or the light exposure. So, when a room is dark or has low light, your eyes will dilate to get as much light as possible into the eyes to see. This response is called the pupillary light reflex. The opposite happens when it is bright outside or in a room. Your pupils will constrict so that the light is not as intense.
Similarly, when you look far out in the distance, your pupils dilate (mydriasis). When you look at something close up, your pupils will constrict (miosis). I explain this in the blog, https://wonderfullymade-kmk.com/what-are-the-parts-of-the-nervous-system/
How vital is the sense of sight?
Your eyesight is essential for communicating with the rest of the body. So much so that your brain dedicates 40%-50% of its space to vision. If someone has visual problems or cannot see, the brain utilizes this space instead for the sense of touch and hearing. That is why when there is a loss of one sense, the heightening of the others occurs. This adaptation is because more neurons are available for the brain to utilize for the other senses. (Huberman, 2024.)
Can you believe how elaborate the process of seeing is; this is just a surface-level view. I hope you learned something new today or made connections that you haven’t before. I had some “AHA” moments myself while reading about this topic. But more than anything, I hope this opens your eyes to sit in awe of how well God has designed every square inch of our body and our world.
Lord, thank you for crafting our eyes to see your beautiful creation. What a complex mechanism so intelligently designed. Thank you for the one reading this; I hope today, as they see your creation, they think of how magnificent you are. To you all glory and praise, Lord, Amen.
SOURCES
Huberman, A. (2021b, June 14). The Science of Vision, Eye Health & Seeing Better. YouTube. https://youtu.be/ObtW353d5i0