Our eye is one of the most wonderful organs in the human body. A cute pair of black and white balls that stay beside each other, work individually and at the same time complement each other. Today, let’s see how these instruments of sight work.
How Do Eyes Work?
Our eyes typically work like a camera. Just like a camera, our eyes also have two components. The first is the focusing system, and the second is the film of the eye.
The focusing system of the eye consists of transparent structures — i.e. the cornea and crystalline lens. In addition to that, we have the iris that controls the pupillary aperture (how much light enters the eye), and the ciliary body that adjusts the focal length of the lens. The transparency and dynamicity of these structures ensure a clear and focused image on the retina — the film of the eye. The brain then processes this image and we finally “see”.
Emmetropia- The state of Harmony!!
Normally, there is a harmony between the focusing system of the eye and the distance of the retina (the film) from the focusing apparatus. This perfect alignment is known as “emmetropia”.
However, sometimes this harmony breaks. The balance may be disrupted either because the focusing system becomes too strong or too weak, or because the retina is not positioned optimally. As a result, the image formed on the retina is blurred. This leads to unclear vision.
This lack of harmony is termed a refractive error — a condition known as “Ametropia”. Ametropia can be broadly classified into three main categories:
Myopia (Near Sightedness)
Here, either the focusing system becomes excessively strong (i.e., the cornea or lens bends light too much), or the eyeball is too long. As a result, light rays converge before they reach the retina. The image forms in front of the retina, leading to a blurred vision for distant objects. However, near objects remain clear.
Hypermetropia (Far Sightedness)
In this case, the focusing system is too weak or the eyeball is too short. So, the light rays do not converge in time and end up forming an image behind the retina. This causes nearby objects to appear blurry, while distant vision may remain relatively clear — especially in younger individuals with strong focusing ability.
Astigmatism
Astigmatism occurs when the cornea or lens is irregularly shaped — more like a rugby ball than a football. This leads to multiple focal points instead of one, causing a distorted or blurred image at all distances. It can occur alone or in combination with myopia or hypermetropia.
Fortunately, all these conditions are correctable. Glasses, contact lenses, and modern refractive surgeries (like LASIK) can help bring back the harmony in this delicate optical system.
So, while our eyes may look simple from the outside, inside they are a marvel of nature — a perfectly engineered camera, crafted by evolution, through which we experience the beauty of the world.
To Know more about all these consitions, check the following video on my youtube channel.