How our body works, Part 6 – taking care of the eyes
By Penelope A. Domogo, MD
Last week, we discussed how images enter our brain through our eyes. These images are also food for our brain. Our brain needs, not only carbohydrates, vitamins and minerals but also needs images (sights), sounds, aroma and touch. All these are interrelated. One of the laws of the universe is the law of transmutation- energy is converted into visible matter and vice versa. Sights, sounds, aroma and touch are also invisible energy. These are processed (or digested) by the brain and become thoughts and meanings. Later these become tangible. Thus let’s be careful with what we feed our eyes just as we choose what images to capture with our camera. For me and my family, we choose not to have TV in the house as TV brings in unwanted guests, with all their cursing and violent behavior.
Aside from taking care of what to feed our eyes, we also need to take good care of the structure of our eyes. Like you need to good care of your camera. But unlike a camera which you can replace when it is damaged, our eyes are so intricate that human intelligence hasn’t yet discovered how to replace it, although some of its parts can be replaced.
Like the camera, our eyes need light to be able to see. 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 the blink often as blinking effectively spreads the tears over the cornea. 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 water the plants. By the way, the cornea can be replaced by modern eye surgery.
Behind the cornea is another fluid called aqueous humor. This clear fluid keeps a constant pressure in the eye and it has a drainage somewhere at the side. If this drainage is narrowed or blocked then there is high pressure inside the eyes. This is called glaucoma and can lead to permanent blindness.
The light then passes through the pupil, the black circle at the center of the iris, is actually an opening which is akin to the aperture of a camera. The iris is the round thing around the pupil which gives the eye its color – brown, green, blue, violet, etc. Take a close look at your eyes. You might see some mestiza color there. (Yon pala contact lenses.) The iris regulates the amount of light going deeper into the eyes to protect the eyes and also give better image. For photographers like me, you know that 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. You know, we, doctors, are also amazed how wonderful God made our 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.
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. Hmm, this is getting very technical, but just to make you realize how intricate the technology of our eyes is (and has been copied by human science).
This lens is what is affected in cataract. Modern technology has produced plastic lenses 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 causing blindness. Just like high blood pressure, cataracts and glaucoma 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 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 into image(s). Can you imagine how complicated the technology is and yet happens so fast! Try to see what is at your side as this moment and you see what I mean.
Other parts of the eye that play important supporting roles are:
1. Sclera – this is the white of the eye that function as a protective covering to the delicate minute structures inside.
2. 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.
3. 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.
4. 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.
5. 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.
There you are, the complex parts of the eyes working in tandem with the rest of the body to give us clear images of the beautiful creation around us. God is good!***
Psalm 66: 4 “Come now and see the works of God, how wonderful he is in his doing toward all people.”