Project One

For the first part of the semester, we focused on critical thinking skills and how to implement them into our everyday lives. The first project we completed focused on learning and how we can use the things we learn to better ourselves through knowledge. This is my first project completed in honors colloquy. The subject was light. This was fitting to the theme of critical thinking given my future career choice of an optometrist. I used the things I discovered in Project One to grow my love and curiosity for my future career. It differs much from Project Two in the sense that it is more informational and contains factual knowledge that I will use in the future. Project Two was an opportunity to explore something solely because I enjoyed it, not because I needed to learn anything about it. Both projects were very unique from one another and I believe contributed to my thinking skills, both creative and critical.

Shine some Light on the Subject

              Visible light is on a spectrum from red to violet, as most of us learned when we were young; ROYGBV. The spectrum of visible light consists of colors fading from purples at the lowest wavelength, to bright reds at the highest wavelength. All these colors of light play crucial roles in how we see the world. Green light is reflected by chlorophyll in plants (while all other colors of visible light are absorbed) and gives them the vibrant green color of lush rainforests and the shady deep green colors of evergreens. The color displayed on objects, such as trees and plants, depends on the wavelength of light reflected. However, in addition to visible light, the electromagnetic spectrum consists of many other wavelengths of light, most of which are not visible to the human eye. Light and its role in our daily lives seems to peak my interest, as a future optometrist. How the human eye interacts with it and other elements of the world around us is key to my successful career. This includes understanding the benefits of light and how it can be potentially harmful.

              So, how do the different types of light interact with our eyes? And how is this different between humans and other animals? The small portion of the electromagnetic spectrum that our eyes are sensitive to is called the light spectrum. According to Andrew Zimmerman Jones from ThoughtCo., this portion of the spectrum is also known as the white light spectrum or the optical spectrum of light (Zimmerman Jones). The visible light spectrum consists of wavelengths of light from about 400 nanometers to approximately 750 nanometers, moving from purple to red. Green light falls around 550 nm and yellow/ orange light around 600 nm (Zimmerman Jones). This wavelength value, which is related to the energy and frequency of the light, determines the color. The end of one color’s wavelength and start of another color’s is widely varied among resources because the colors all blend together on the spectrum of visible light.  White light is composed of wavelengths of all or most colors of visible light (Zimmerman Jones). Sending a beam of white light through a prism splits the beam into its component wavelengths, displaying a rainbow of colors.

              Some animals have a different range of visible light than the human eye, sometimes extending into the infrared light spectrum, or down into ultraviolet light. Infrared light expands beyond 700 nm and ultraviolet light falls in the range lower than 380 nm (Zimmerman Jones). Most animals that can see infrared light cannot see ultraviolet, and vice versa (Zimmerman Jones). Birds, bees and insects can see ultraviolet light. Flowers use the ultraviolet light to attract pollinators while birds have visible markings under a black (ultraviolet) light (Zimmerman Jones).

              On the lower edge of the wavelength for visible light, is ultraviolet light. Many of us have heard as UV light as bad for the skin by causing damage to our cells. If it is so potentially hazardous to the outside of our bodies, what happens when it reaches the inside of our eyes? Ultraviolet light is typically noticed as UVA and UVB. UVA is light from 315- 400 nm (WIkipedia). It has a longer wavelength and is not absorbed by the ozone layer. This UVA light is the wavelength of light associated with “black lights”. Unlike UVA light, UVB light is mostly absorbed by the ozone layer. It falls from 280- 315 nm (WIkipedia). Ultraviolet light is invisible to the human eye. Our lens ordinarily filters out UVB frequencies or higher. In addition, our retina also lacks color receptors (called rods and cones) to absorb and interpret the UV rays. Some people are affected with a condition called aphakia. A missing lens or replacement lens characterizes this condition. These individuals have the ability to see some ultraviolet wavelengths (WIkipedia). While this type of light surrounds us every day, it can be damaging to cells. This includes our cells on the inside back of our eyes. UV light damages cells by damaging their DNA. An accumulation of damaged DNA kills the cells (Rammelsberg and Baxter). Ultraviolet light causes a reaction between thymine bases that make up DNA. The reaction binds two thymine to one another, creating something called a thymine dimer. While this damage can be repaired, the longer the exposure to the UV light, the more thymine dimers are created and the more difficult the repair to the DNA (Rammelsberg and Baxter). This type of light can be used to “sanitize” or to kill bacteria on surfaces. However, it can also damage the cells in our eyes that help us to see, the rods and cones. This can cause diseases like macular degeneration later in life.

              Many of us hear polarized sunglasses are much better for your eyes and protecting them from the sun. But why is this? Well, it turns out polarized sunglasses are better for your vision, not for your eye health. Polarized lenses block glare by blocking scattering waves of light, specifically from horizontal surfaces, but they do not add any extra protection from UV light (Vision Source). Polarized lenses finely tune your vision, especially during outdoor activities that introduce large amounts of glare. They were actually created by NASA Jet Propulsion Lab Scientists who studied the eyes of eagles to better understand their sharp visual acuity. They found a naturally occurring oil in eagle’s eyes that control certain properties of light by scattering and limiting certain wavelengths (Vision Source). These scattered wavelengths are known as glare and are also those absorbed by polarized filters in lenses, creating “eagle eye” sharpness for humans.

              With emerging use of technology, our eyes are exposed to many different wavelengths of light. While very useful to our everyday lives, I wondered how is technology affecting our eye health? Computers, phones, and tablet screens, as well as fluorescent lights and the sun emit different wavelengths of blue light. Specifically, we are exposed to more blue light around 400 nm on the visible light spectrum. Sometimes, this can be considered “harmful blue light.” This light is considered as potentially harmful because it is absorbed deep within the eye and has the possibility to affect future vision. This damage can result in macular degeneration, and with increasing technology use, this disease diagnoses has increased in younger generations. The most damaging wavelength of blue light is between 415- 455 nm (Arnault, Barrau and Nanteau). To combat the increase in exposure to blue light, some optical lens companies have innovated technology to emit harmful blue light rays. Essilor, one of these companies, has created a blue light technology that absorbs this blue light into the lens on a pair of glasses to prevent it from reaching the eye. Certain anti-reflective coatings made for lenses are designed to reflect blue- violet light in the wavelength frame of 415- 455 nm. This can be visibly observed because the blue- violet color is emitted back off of the surface of the lenses. This prevents the harmful blue light from ever reaching the eye and causing damage.

              Blue light can’t be all bad, right? Many wavelengths of blue light play a crucial role in our sleep- wake cycles and the role of the hormone melatonin that controls sleep induction. The light from our devices inhibits the production of melatonin. This hormones levels are low during the day and are heavily influenced by light. Many pieces of technology now have a “night light filter.” This filter appears more yellow in color than the typical color of light emitted by a screen. This yellow-ish orange color helps to eliminate the wavelength of blue light our eyes are sensitive to during the day, and that our brains use to stay alert during waking hours.

              After all, light seems to be helpful and harmful to our everyday lives. Like with many things that come with a good and a bad side, understanding it to control the damage is the best measure of prevention. I feel as if many questions I had about light before are now answered and it will benefit my future career because of it. Knowledge is power and educating yourself for no other benefit than your own can bring about a passion for a topic that can help you affect others lives as well. I know that my thirst for knowledge about our windows to the world is far from quenched and I am so excited to have begun my journey on learning all I can. There are so many factors that affect our vision and light is just one of them. I truly want to use what I have learned to ignite a light inside others to be aware of the world around us, the possible risks we can see and those we can’t. Even with this small step and little amount of research, I feel as if I can shine a light on eye health education (pun intended).

Works Cited

Arnault, E., et al. Essilor: Lenses for Harmful Blue Light Protection. 23 August 2013. https://essilorusa.com/products/blue-light-eye-protection. 2 February 2018.

Rammelsberg, Anne and Bonnie K. Baxter. "How does ultraviolet light kill cells? ." n.d. Scientific American . https://www.scientificamerican.com/article/how-does-ultraviolet-ligh/. 2 February 2018.

Vision Source. Polarized Lenses Give You an Eagle-eye Advantage. 3 August 2016. 9 March 2018.

WIkipedia. Ultraviolet light. 30 January 2018. https://en.wikipedia.org/wiki/Ultraviolet. 2 February 2018.

Zimmerman Jones, Andrew. "Visible Light Spectrum—Overview and Chart." 18 September 2017. ThoughtCo. https://www.thoughtco.com/the-visible-light-spectrum-2699036. 3 February 2018.