From Light To Dark

From Light to Darkness: A Journey of Our Sight

Our eyes are amazing sensory organs that allow us to see and appreciate the world around us. The eyes are made up of many complex elements that work together to provide us with optical information about our environment. Cones and rods are key receptors in the retina that convert light energy into neural impulses, transmitting information to our brain.

When light enters the eyes, it hits the retina, where it is converted into nerve impulses. Cones and rods are receptors that convert light into nerve impulses. The rods contain the photopigment rhodopsin, which consists of two molecular parts: retinin, a derivative of vitamin A, and the opsin protein. Light separates retinin from opsin, and in this process the light energy is converted first into chemical energy and then into impulses generated by nerve tissue.

The complexity of this process can be seen in adaptation to darkness, for the retina is capable of accommodating its light sensitivity to 100,000 different gradations of light. When moving from bright light to darkness, rods adapt within 10 minutes, while cones take 20-25 minutes to reach 90% adaptation. On the contrary, when moving from darkness to light, these changes occur in a few minutes.

Our vision also has the ability to see in three dimensions thanks to binocular vision. Instead of seeing the world through one eye, we see it through two eyes, which create a sense of depth and dimension. The brain combines both images and creates a sense of depth or relief (stereoscopy).

To understand how binocular vision works, you can conduct a simple experiment. Place a sheet of cardboard vertically on the line AB of the drawing and lean your nose and forehead against its edge so that the right eye sees only the drawing on the right, and the left eye sees the drawing on the left. In this case, both geometric figures will merge into one - a three-dimensional truncated pyramid, seen from above.

But our vision is not perfect: we have blind spots in our retina, where there are no photoreceptors and the light entering this area is not perceived, so no nerve impulse occurs. This area is called visual discomfort. We also have a limited ability to distinguish colors, especially in low-brightness environments or in the presence of colored lighting. Some people have vision problems such as farsightedness or shortsightedness, which can be corrected with glasses or contact lenses.

Our vision can also be damaged by various diseases such as cataracts, glaucoma or retinal degeneration. These diseases can cause vision impairment, and in some cases can even lead to blindness.

Overall, our vision is an amazing and complex organ that allows us to see and appreciate the world around us. We should take care of our vision and see an eye doctor for regular checkups, especially if we are at risk of developing eye diseases.