By Penelope A. Domogo, MD
Our eyes are the organs of the body that make us see the world around us. They are complex structures, perhaps the most complex in the body, and very interesting. They are roundish that’s why sometimes we call them eyeballs. They function like a camera. And like a camera, the eyes need light to see. (You see, modern technology copies from nature.)
The first thing that light strikes in the eye is a very thin veil of tears. Tears are important as they keep the covering of the eye moist and clean. The outermost part, a transparent curved covering called the cornea, helps focus light. When the cornea dries up, they get damaged and scarred and could then diminish vision. Thus it is important for us to blink often as blinking effectively spreads the tears over the cornea. Blinking is also an automatic action of the eyes to ward off injury. You automatically blink when you see an object getting close to your eyes. The problem is that when you watch TV or movies, especially action-packed movies, you tend to keep your eyes open because you don’t like to miss the next scene. This will dry the cornea and strain the eyes. So when watching TV, you have to consciously blink or better yet, turn off the TV and wash the dishes.
Behind the cornea is another fluid called aqueous humor. This clear fluid keeps a constant pressure in the eye. The light then passes through the pupil, the black circle at the center of the iris, which is akin to the aperture of a camera. The iris gives the eye its color – brown, green, blue, violet, etc. It acts like the diaphragm of the camera regulating the amount of light going deeper into the eyes to protect the eyes and also give better image. Just like when you don’t correctly adjust the aperture of your camera, the resulting picture will be too bright or too dark. Try looking at the pupil of your friend using a pen light- when you direct the light on his/her eyes, you will see the pupils constrict and when you remove the light, you will see them automatically dilate. It is amusing. This is what the doctor does when s/he examines your eyes. Observe also how the pupils dilate when your friend is interested or excited in something or someone. Not only do the pupils dilate, the eyes also widen. Apparently, the body wants to maximize the sense of sight.
Just behind the pupil is the crystal-clear lens that automatically focuses the light and changes shape according to what you want to see- a near or far object. Just like an autofocus camera lens. The light then travels farther through a clear jelly called the vitreous before finally striking the retina, the inner lining at the back of the eye- a thin layer of light-sensitive cells. The retina acts like the electronic image sensor of your digital camera.
The lens is what is affected in cataract. Modern technology has produced plastic lenses that doctors use to replace those damaged by cataract. Eye doctors are so skilled nowadays and with fine gadgets, that they can do cataract surgery easily. The retina can also be detached. Just like high blood pressure, cataracts and other eye diseases are diseases of modernity. Diet is the main culprit.
Just like other sensory mechanisms of the body, these light-sensitive cells are connected to nerves endings which convert light into electro-chemical signals which are then transmitted by the optic nerve to the brain. It is not just transmitted anywhere in the brain. Our body is so amazingly, unbelievably, organized. These signals are transmitted to the visual center at the back of the brain where the light is then translated into an images or images… in full color. In effect, it is the brain that “sees”. It has been said that the brain is the biggest sense organ.
To summarize how we are able to see: Light is reflected from an object, enters the eye which focuses it and converts it into electro-chemical signals which are then transmitted to the brain where it is then translated as an image. How complicated the processes are and yet they happen so fast.
Other parts of the eye that play important supporting roles are:
Sclera – this is the white of the eye that function as a protective covering to the delicate minute structures inside.
Eye muscles – the eyes are small and yet each eye has 6 muscles that enable it to rotate, upward, downward, sideways. Thus you are able to see your pet peeve coming even without turning your head and pretend you didn’t see him or her. Even without moving our eyes, we can actually have a 180 degrees field of vision. God is really wonderful.
Tears – I again mention tears because they play an important protective function to the eyes. Tears contain not only water but salt, mucus and other natural germicidal substances! We have tears everytime but only in the amount needed to keep the cornea from drying and there is a tear duct or canal at the edge of our lower eyelid where the fluid constantly drains unnoticed to our nose. When this tear duct is clogged, usually in the elderly, then tears will flow out from the eyes. “Mendandanum nan mata.” It’s usually only one tear duct that’s affected. When some irritants like dust or splinter lands in your eye, the eyes automatically produce much tears to wash away the foreign body. Sometimes also, tears overflow to wash away intense emotions from your body. Tears of joy or tears of sorrow or tears of anger. Tears have a great cleansing function.
Blood vessels – these are so minute and thus so delicate so take care that these are not clogged by sugar and fat. What happens to your heart and kidneys also can happen to your eyes. Our body is one whole system and all parts are connected. We have only one circulatory system and one kind of blood – the blood that flows in your hand is the same blood that flows in your eyes. So keep your diet natural- fresh and plant-based as much as possible.
Eyelids and eyelashes – these protect our delicate eyes from injury. Imagine if we had no eyelids and eyelashes. Aside from looking weird, our eyes would be damaged in no time. Our lids blink automatically when something gets near enough – remember the game of who won’t blink when somebody’s fist is shoved near the face. I don’t ever get to win that. And look at our eyelashes. They protect our eyes from dust, komao, etc. And whether they are curly or not, long or short, they give equal protection.
Our eyes are wonderfully made, just like the rest of our body. Let us take care of them.**
“The eye is the lamp of the body; so then if your eye is clear, your whole body will be full of light.” Matthew 6:22