The Eyes Have It
The eye is the lamp of the body, the window to the soul, and a mirror of the heart, according to the various philosophers, poets and evangelists. Just what is this amazing organ, which many describe as an incredible gift of nature, that it can be all these things? Attesting to its intricacy and importance, the human eye is the smallest single organ to have an entire medical specialty (ophthalmology) and an entire ancillary medical specialty (optometry) devoted to preventing and treating its problems and maximizing its usefulness.
As perhaps the most important and most cherished purveyor of the five senses, our eyes play a unique role in how we navigate through life in a world overflowing with visual stimuli. Let’s take a closer look at this amazing organ, reviewing some of the basics of how the eye works and what we can do to care for them. In future articles in this series we will review some of the more common eye disorders.
How the Eye Works
Just one example illustrating the incredible nature of the eye is the way in which it evolved in a similar manner over time in animal lines as divergent as cephalopods (such as squid), vertebrates (such as mammals, reptiles, birds and fish) and cnidaria (such as jellyfish). Some would call this an accidental phenomenon known as convergent evolution. Others see this as a purposeful miracle created by a greater power. Regardless, in each of these different types of living organisms the end result of the development of the eye has been similar, basically resulting in a structure that operates like a camera.
Light rays reflecting an image first pass through the cornea, the transparent structure that covers the front part of the eye. The light rays are then focused and directed through the pupil, the dark, circular opening in the center of the colored iris that operates in a similar fashion to the aperture on a camera. The rays then pass through the lens which helps to focus them on the retina lining the back inner surface of the eye. The retina is analogous to the film of a camera but contains photoreceptor nerve cells that convert the light into electrical impulses which then travel by way of the optic nerve to the brain where the image is perceived. Of course, there is no way to adequately describe the workings of such an incredible organ in just one paragraph, but this will give you the basics to build on as you continue to explore the wonders of the human eye on your own.
Basic Eye Care
There is much that you can and should do to ensure that your eyes stay healthy for a lifetime. Basic eye care includes proper nutrition and exercise, wearing protective eyewear, knowing your family health history and getting regular eye exams at the appropriate intervals. A diet rich in fruits, vegetables (especially green, leafy vegetables) and fish has been shown to be beneficial to the eyes. Maintaining your ideal weight and not smoking is also important to prevent diseases that affect the eyes, such as diabetes and macular degeneration. Wearing the appropriate protective eyewear both at home and in the workplace is essential, whether it be while engaging in sports and other recreational activities or operating equipment like a weed eater while gardening at home. Wearing sunglasses will protect your eyes from the harmful effects of UV radiation from the sun.
‘Near work’ such as looking at a computer screen can strain your eyes, so resting the eyes at intervals during such activities is important. For children, unnecessary near work such as playing computer games should be limited and substituted instead with outdoor activity. Studies have shown that daily outdoor activity may prevent the development or progression of myopia, a refractive error making distant objects appear blurred. Finally, regular eye examinations throughout life (especially important during childhood and the golden years) will help identify eye problems early so that corrective measures can be taken. In our next article we will take a look at some of the common eye disorders.