Almost every living thing has eyes, it is the most intricate part and the fastest muscle of mammals. Interestingly, the eye doesn’t grow. The eyes are the organ of the visual system. They help to provide vision and interpret visual details. Our eyes work with our brain to tell us the shape, colour, texture and size of an object. Individuals without vision are handicapped and depends on external aid for movement.
The eye also known as eyeball is fitted into the eye socket (also called the orbit) which is surrounded by bones and connects to the brain. Surrounding the eye is the eyebrow which is above the eye and the eyelids where the eyelashes extend. Other components of the eye are the cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous, but the visible part of the eye are the eyelids, cornea, pupil, sclera which are seen in a person’s face.
What are the functions of these components?
The eyebrow shields the eye from sun, prevents sweat, water and other debris from falling down into the eye socket that’s why no amount of sweat found on the face can cross the eyebrow. But they are also use for communication and facial expression (non-verbal expression).
The eyelids and eyelashes prevent dirt, sharp object and dust. This explains the reason you unconsciously blink when an object is approaching the eye.
The sclera is the opaque, fibrous and whitish part of the eye. It is the protective part of the eye.
The cornea is the transparent structure outside the eye which connects to the sclera at the corneo-scleral junction. It serves as the front window of the eye which focuses light into the eye.
The iris is the coloured part of the eye that controls the amount of light that enters the eye. The colours differ: the most common is brown.
The pupil is an aperture located in the iris that determines the amount of light that goes to the lens.
The lens is another transparent structure of the eye but found inside unlike the cornea which is found outside, it focuses light rays to the retina.
The retina is the innermost layer of the eye which lines the back of the eye, receives light refracted from other transparent structures, create signals that travels to the optic nerve.
The macula is a small yellow spot in the retina that contains light sensitive cells and allows for vision of fine details clearly.
The optic nerve is the nerve that connects the eye to the brain, it also carry impulses formed by the retina to the visual cortex of the brain. It is said that we see with the brain because our eyes see things upside down but the brain inverts the image the right way.
Screen is a flat area in an electronic device such as a smartphone, computer or television on which images and data are displayed. Today, most of our activities demand the use of screen. At the office, we fix our gaze at the screen of the projector, television, computer or smartphone. In the hospital, the scanning machines has screen we look to, you see we spend long hours on digital screen. Most of us spend majority of our waking hours staring at the digital screen. One similarity of this digital screen is the emission of light.
Light is made up of electromagnetic particles which travel in waves, and these waves emits energy, and range in length whereby the longer the wavelength, the lower the energy. Light is divided into visible and non-visible light; the visible light is that which human eye is sensitive to and its colours are red, orange, yellow, green, blue, indigo and violet (ROYGBIV). While the non-visible are the gamma rays, x-rays, ultraviolet (UV) rays, infrared light and radio waves.
Blue light has a short wavelength and a high amount of energy. It is a high-energy visible light (HEV). Though blue light is everywhere, it is part of our daily intake from sunlight. It keeps us alert, assists memory and elevates mood but there has been increase exposure of blue light due to evolution of digital screen technology from Cathode Ray To(CRT) to Liquid Crystal Display(LCD) to Light Emitting Diode (LED). It’s been known to cause flickering and glaring.
Effect of blue light on the eye
- High exposure blue light at night cause
- Reduction in melatonin, the hormone responsible for sleep.
- Disruption of circadian rhythm
- Digital eyestrain – symptoms are dry eye, dizziness, blurry vision, difficulty in focusing and headaches. Sitting in front of your screen causes dizziness, neck and shoulder strain.
- Macula degeneration – I explained above what macula is, a small spot where fine detail is clearly seen. These results from the death of cells in the center of the retina, which leads to Age-related Macula Degeneration (AMD) and ultimately vision loss.
- Follow the 20-20-20 rule. After 20 minutes, take a 20 seconds break and look at an object around 20 feet away.
- Blinking helps to regulate blood circulation in your eyes, it helps clean your eyes, grease them and give them a break from light. With the lack of frequent blinking, your eye becomes dry which leads to inflammation and poor vision. This practice is especially useful for those who work with anything that requires a lot of attention such as reading and frequent use of the screen.
- Reduce screen brightness to the minimum.
- Stay at least 3m from your television and 40-50cm from your smartphone or computer
- Use blue light filter which some is embedded in smartphone such as night mode, eye care, night light, flux, twilight, iris
- Use your device at least an hour before bedtime.
- Pick a book or any activity to wind you down before sleep.
In this present times, it may be difficult to keep oneself from digital screen as most are required for entertainment, education and our daily work but adhering to the preventive measures can limit its exposure.
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