The eye is a pretty spectacular thing.
For most of us we wake up in the morning and open our eyes and get a view of the world. But, most of us know that our vision is not perfect.
Some of us rely on glasses, some on contact lenses, and some have even had surgeries to correct the vision. (The list of the different types of procedures that are used to correct nearsightedness, myopia, or farsightedness, hyperopia, and astigmatisms is getting lengthy.) But, surgery is an extreme, and most of us if we need a bit of correction to clear our vision rely on either glasses or contact lenses.
The human eye works like a camera. Light enters the eye through the cornea then the lens which focuses the light on the specialized nerve cells on the retina. The cornea is the outer most lens and is fixed in shape.
It accounts for between 65 and 75 percent of the eye’s ability to focus. The lens, in contrast, is flexible and can change shape. It is the combination of both the lens and the cornea that focuses the image on the retina. There are a number of things that can ultimately affect, how this combination works the shape of the cornea, age and loss of flexibility of the lens, and damage due to health changes or injury.
So, just like a camera, if things get a bit out of focus, we can add a lens to sharpen the image, and for our eyes, this is the addition of glasses or contact lenses.
However, for extreme cases or for some who opt don’t want to use glasses, there are the elective surgeries to reshape the cornea to provide for clearer vision. It should be noted that there are also changes in vision related to the change in the tissues, and not the shape. Cataracts, a clouding of the lens, is such a change. But, for this discussion, we are focusing on the physical, i.e., the image formed due to the physical shape and configuration, much like manipulating a combination of lenses in a microscope or telescope to get the correct magnification and focus. But, there are also cases, where the cornea or lens are damaged and need to be replaced or transplanted for a person to be able to see.
Helping people to see clearly is big business, the US Vision Care Market, according to Vision Monday, a trade publication, that business in 2016 was over $34 billion.
This means that there is a great deal of opportunity for the material scientists and medical to find interesting projects.
For example, at the fall meeting of the American Chemical Society, there was a report on the development of an ultrathin implantable film that could be used as an artificial retina. The film, developed by a group at the Cockrell School of Engineering at the University of Texas, is an atomically thin wafer of graphene and molybdenum disulfide. This material can be directly laminated on the skin and has been used as an electrode which allows for the measurement of signals like those seen in an electrocardiogram. Because of the physical properties of the material, the researchers believe that this type of material could be used to replace retinas damaged as a result of macular degeneration or retinitis pigmentosa. This type of research is in addition to the work on materials such as transition lenses or other materials that can be used for glasses or contact lenses.
As with any material, there are the lifecycle concerns. If you are a contact lens wearer, have you ever thought what happens to the lens when you discard it?
Another paper at the American Chemical Society meeting was related to the environmental fate of these lenses. Work by Ralf Halden at Arizona State University indicated that 15 to 20 percent of contact lens wearers are flushing their lenses down the sink or in the toilet. His team looked at what happens to the lenses as they work through the sewer system and have found that these lenses end up at the wastewater treatment plants. His team estimated that contact lenses could account for up to 10 metric tons of waste, and the characteristics of the lenses make them a challenge, they sink and are clear.
Our vision is important. Understanding, how the eye works has made it possible to help correct vision issues. Developments have allowed us to approach things like a bionic eye which was once thought to be science fiction.
Editor’s note: This is a series of science-related articles by author Frankie Wood-Black, Ph.D., REM, MBA, to appear in Mid-Week section of the Ponca City News. The author currently runs her own environmental consulting firm based in Ponca City, Sophic Pursuits, Inc., and also serves as a Physics Instructor and the Director for Process Technology at Northern Oklahoma College.