The Science Behind the Eye
Many a time you’ve probably thought of your eye color or if your eyes change color. But have you ever wondered about why your eyes are colored? Or how do you see from them and how do they send signals to your brain? Or how you get those deformities in your eyes that make them not work right? If so, did you find out or did you just concoct an idea that may or may not be plausible. It's time to finally figure out what is happening with your eyes.
Light entering the eye is first bent, or refracted, by the cornea, the clear window on the outer front surface of the eyeball. The cornea provides most of the eye's optical power or light- bending ability. After the light passes through the cornea, it is bent again to a more finely adjusted focus by the crystalline lens inside the eye. The lens focuses the light on the retina. This happens by the ciliary muscles in the eye changing the shape of the lens, bending or flattening it to focus the light rays on the retina. This adjustment in the lens, known as accommodation, is necessary for bringing near and far objects into focus. The process of bending light to produce a focused image on the retina is called refraction. Normally the light is refracted in such a way that the rays are focused into a precise image on the retina.
Most vision problems occur because of an error in how our eyes refract light. In nearsightedness, the light rays form an image in front of the retina. In farsightedness, the rays focus behind the retina. In astigmatism, the curvature of the cornea is not normal, causing light rays to focus to more than one place so that a clear image can not be formed on the retina, resulting in blurred vision. As we age, we find reading or doing close up activities more difficult. This condition is called presbyopia, and happens from the crystalline lens being less flexible, meaning less able to bend the light.
Now for the coloring. The iris is the colored part of the eye surrounding the pupil, and it is made of layers. The iris pigment is in the back and has some black or brown pigmentation to it. The layer over it is the stroma, which sometimes has brown pigment. The black dots you see in the eye are typically coming from the epithelium and are visible through the stroma. Color is determined by the amount of melanin in the stroma. If you have brown eyes, you have brown melanin in the stroma that will absorb take in light and make the iris appear darker in color. If you have green eyes, there’s not much melanin or collagen, and the light will be scattered. If your eyes are blue, you have no melanin at all of the light hitting the eye is scattered and reflected back. That’s why people with blue or green eyes can seem to change eye color,, depending on the amount of light in a room.
The eye really is a simple thing when you look at it. It is mostly just light refraction and bending the light to form a precise image to actually see, with the eye color being just a pigment and a certain amount of light that your eyes receive. That’s really it; eyes are very simple. Just remember that when you’re looking at your friends or watching a video or playing a game, it is just a reflection of light.
By Isaac