Design Life-Cycle

Flor Barillas

March 13th, 2016

DES040A-A03

The Life Cycle of Soft Contact Lenses: Raw Materials

           If a person does not want to wear eye glasses, then an alternative is to wear eye contacts. There are two types of contact lenses: hard contact lenses and soft contact lenses. Hard contact lenses are known as semi-rigid gas permeables and made out of plastic-like material; they are not very comfortable to wear and so they are not very popular with consumers. Soft contact lenses on the other hand are very comfortable since they are made out of very flexible breathable plastic-like material. In this paper, I am going to be delving into the life cycle of soft contact lenses as well as the raw materials that go into making this product, how these raw materials are made/obtained, and describe any other materials that may come up during the life cycle.

          The first step of the life cycle of soft contact lenses is to acquire/make the materials needed, which are hydrogel and silicone. Soft contact lenses are made primarily out of two materials: a plastic polymer known as Poly Hydroxyethyl Methacrylate (Woodward) (more commonly referred to as hydrogel) and silicone. Hydrogels are a type of polymer that absorb water to transmit oxygen from the contact lenses to the eyes – some can hold up to as much as 70% water (“How Are Contact Lenses Made?). Contact lenses are also made of silicone, which allows more oxygen to enter the lens to the eye while avoiding the problem of the lens becoming too big due to the hydrogel. First, we will discuss the (complicated) steps in order to make hydrogel and then we will go over the (relatively simpler) steps to make silicone. The most popular types of soft contact lenses are made from “thermos-set polymer hydrogels” that are made from “three dimensional, amorphous network[s] with cross-links,” which later included surfactants such as N-vinyl pyrrolidone (NVP) and Methacrylic acid (MAA) (“Bergin”). Hydrogels can be made out of hydrophilic monomers or out of polymers that are either synthetic or natural. Hydrogels are made in a similar fashion as polymers are made since hydrogels are in essence polymers, which are a blend of materials created by linking the molecules of different chemicals (Woodward). A common way to create hydrogels is through copolymerization which is when hydrophilic monomers react with multifunctional cross-linkers (Ahmed). Other ways of making hydrogels from synthetic and/or natural polymers is by combining crude oil with elements such as carbon (White). Other than hydrogel, silicone is also needed in order to make silicone hydrogel contact lenses. Silicone like hydrogel is an artificial polymer, that is, it is not something found in nature rather it is made through various chemical reactions. Silicone is made out of a silicon and oxygen based polymer. Silicon is found in sand and when extracted and “passed through hydrocarbons” then silicone is made and formed (“Is Silicone a Plastic?”). When combined with hydrogel, then silicone hydrogel is made, forming soft contact lenses. Other raw materials that can be found in the lifecycle of soft contact lenses are the materials used to make the packaging, because no one gets contact lenses without any packaging to keep the product from getting harmed during transportation. The packaging that soft contact lenses come in are made from fairly easily obtainable materials: cardboard, plastic foil, aluminum foil and saline solution in which the contact lenses are encased in. And like the brief aforementioned mentioned process of making polymers, these materials are made in similar ways, so as to not stray from the lifecycle of contact lenses, how these materials are made will not be included.

          The second step of the lifecycle of soft contact lenses is the manufacturing, processing, and overall formulation of the product. Soft contact lenses can be made in various ways, by cast molding, lathe cutting, and spin casting (Bergin). The least common type of contact lens manufacturing is the lathe cutting method. Lathe cutting is when the silicone hydrogel is on a small rotating mount while machines cut and get rid of any extra material on the lens so they are not bulky. Then, the silicone hydrogel lenses are polished and double checked to make sure they are suitable for consumer use. Lathe cutting is the least popular method of making contact lenses because even though it does give better quality silicone hydrogel lenses, it requires more advanced technology, more resources, and more time (“How Are Contact Lenses Made?”), which is something that manufacturers are not willing to do. A more common type of manufacturing for soft contact lenses is spin casting. In spin casting, liquid polymers are injected into a spinning mold where they can be polymerized. What the spinning mold does is use “centripetal force” to form the base curve of the lens and the front curve is formed by the curvature of the mold (Kamat-Paranjupe). The molds all have smooth surfaces and tapered edges to ensure that the contact lenses come out smooth enough so that consumers can wear the product with little to no irritation. Ultraviolet lights are then turned on to allow the silicone hydrogel to harden/solidify before they are removed from the mold and hydrated in a sterile water bath. The advantages of spin casting are that not only are the lens guaranteed for enhanced comfort for consumers but they are also easy to fit, which means little lens movement while being worn by consumers (Kamat-Paranjupe). The most common and most used type of manufacturing for contact lenses is cast molding, also known as injection molding. Cast molding is the most cost efficient way to mass produce soft contact lenses, which is why it is the most popular manufacturing method. First, the silicone hydrogen is injected into molds under pressure, then it is removed and cooled before being inspected for any damages. All of this is done through computer controlled systems (Woodward). This type of manufacturing is able to produce contact lenses without the need for polishing them before packaging them and shipping them to distributors (Kamat-Paranjupe). Any one of these manufacturing methods could be used to produce soft contact lenses out of silicone hydrogel, and although some methods are more commonly used by others, ultimately it is up to the manufacturer/company to decide which of these methods they use.

          The third step in the life cycle of soft contact lenses is the distribution and transportation of the contact lenses. In today’s society, many people prefer contact lenses to eyeglasses, and so it is no wonder that companies such as Acuvue distribute soft contact lenses to “over 70 countries worldwide” including Australia (Marika). The most usual ways to transport soft contact lenses, as with any other product, is by plane or truck which both use natural resources such as fuels, whether they be jet fuel, gasoline, or diesel. In order to provide a better mental picture of just how far transportation for a contact lens can be, I thought to provide an example. If a consumer who resides in Brisbane, Australia orders soft contact lenses from a manufacturer such as Acuvue, then the order would be produced at their nearest manufacturer which, for the sake of this example, is in Limerick, Ireland. Then, the distance that a plane would have to fly is 10,450 miles. And if a ship had to make the delivery, then it would travel 11747 miles (Marika). And that is not including the miles that a delivery truck would be driving when out delivering packages. This step in the lifecycle is quite quick compared to the first two, but it is still nevertheless important. Without the distribution and manufacturing, then consumers would have to figure out a way to get their contact lenses themselves.

          The next step of the life cycle is the use, re-use, and maintenance of the soft contact lenses. By this step, the consumers have already gotten their soft contact lenses delivered to them. If not properly cared for, contact lenses can lead to discomfort and eye infections. However, caring for soft contact lenses is not very difficult, as there is an abundance of information on how to care for them online. Before putting in the contact lenses, the consumer must first make sure to wash their hands so as not to contaminate or dirty lens. “Try to avoid moisturizing soaps, as they are not good for [soft] contact lenses” (White). After they have washed their hands, the consumer should dry their hands with a lint free towel so they do not get any fabric residues onto the contact lens. Next, the consumer must remove one of the contact lenses and clean it with a solution. There are mainly two types of contact solutions out in the market today, multipurpose contact solutions and peroxide solutions. Multipurpose solutions usually use a “polymeric disinfection agent such as polyhexamethylene biguanide or polyquartenium, which incorporates quaternary ammonium centers… Using polymers instead of monomers [in the multipurpose solution] provides effective antimicrobial activity while still being gentle to the eye” (Kemsley). Peroxide solutions on the other hand use mainly two main ingredients, a 3% peroxide solution and a neutralization catalyst; “While the peroxide does a fine job of killing whatever microbes might have latched onto lenses, it’s not very eye-friendly, so a platinum, palladium, or silver catalyst is used in… to completely neutralize the solution by reducing the peroxide to form oxygen and water” (Kemsley). Anyway, after having washed their hands and cleaning the lens, then the consumer should rinse the lens once more to make sure the product is clean. Finally, the consumer must place the lens back in the lens case with new solution, usually a saline solution which is made primarily of sodium chloride and water. After cleaning and storing the first lens, the consumer will repeat these four step with the remaining contact lens. Depending on the type of soft contact lens the consumer has purchased, then how long they can use the product varies. There are disposable contact lenses and extended wear contact lenses. Consumers can choose between disposable contact lenses which can last from one use (so one a day) or extended wear contact lenses, which can be worn several times within a span of two weeks (DePaolis). There are also frequent replacement lenses which are replaced monthly or quarterly, and traditional reusable lenses which are replaced every six months or longer (Segre), though these are not the most popular among consumers. While there are advantages of each type of contact lens, depending on customer preference when they discard and repurchase contacts is up to them.

          The fifth step in the life cycle of is recycling. Contact lens cases can be recycled, as they are made of plastic #5 (“Great News If You Wear Contact Lenses”) and so can contact solution bottles. Contact solution bottles are not biodegradable as they are made out of hard plastic so if they are not recycled properly they will just sit in landfills and over time release harmful toxins to the environment. Because disposable lenses are most used by consumers, the plastic waste that the cases in which the lens come in begins to accumulate, so it is best to recycle these cases to reduce plastic waste (“ Great News If You Wear Contact Lenses” ). If unrecycled, the amount of plastic waste sitting in landfills could add up over time and soon become a problem. The contact cases and contact solution bottles can be recycled through some curbside programs, which eventually turn these plastics into objects such as: battery cables, brooms, brushes, signal lights, etc. They can also be recycled at Preserve Gimme 5 locations throughout the US or mailed in if there is not a location close by (“Great News If You Wear Contact Lenses”). In order to recycle these products, they must be melted at 173 degrees Celsius before being poured into a mold that will turn it into another product (“Plastic Recycling”). Contact lenses themselves cannot be recycled if the lenses have been used or if they have expired (Marika). If a consumer has unused contact lenses that are not expired, then they can be returned to the manufacturers to redistribute them to someone who will use them.

          The last step in the life cycle of the soft contact lenses is the waste/ waste management. As mentioned before, contact lenses cannot be recycled unless they are unused and have not yet expired. But even then, they are not recyclable so they can be thrown away like any other piece of garbage. Contact lenses are not treated any different from any other disposable garbage that ends up in landfills. In addition to being left in landfills, these polymers can be incinerated but if they are not burned at a high enough temperature, then toxic gases such as carbon dioxide are produced, which contribute to the growing global warming epidemic we are facing (Coelho). If they are not incinerated, these polymers have the capacity to sit in landfills for a very long time – longer than any human life. The amount of contact lenses needed to be a posing problem in landfills is most likely more than the amount being worn today. “According to data collected in the early 200s by Eurolens Research… a single pair of soft contact lenses weighs about 25 milligrams after it’s been dehydrated. Twenty-six pairs of your biweekly lenses, then, would produce about 0.65 grams of dried out plastic. A year’s worth of Lantern’s own daily disposables – that’s 730 lenses total – would produce 9.125 grams of plastic – or a little less than would go into the production of two credit cards” (Rastogi). So while the amount of waste contact lenses themselves are producing now is not an overwhelming problem, we should look into ways that will allow us to recycle them so that they do not become a foreboding problem in the future.

          In conclusion, throughout this paper we looked at not only the raw materials that make up soft contact lenses, but at the overall life cycle of the product. This will help consumers be more aware of what is in and what goes into making a product like soft contact lenses, a product that many people use on almost a daily basis. From the beginning of the life cycle up until the very end, many different types of materials go into making, manufacturing, distributing, maintaining, and even recycling/disposing of soft contact lenses. The materials that go into making soft contact lenses do not just include hydrogel and silicone, but a whole variety of other types of materials as well.

Bibliography

1. Ahmed, E. "Hydrogel: Preparation, Characterization, and Applications: A Review." Hydrogel: Preparation, Characterization, and Applications: A Review. Mar 2015. Web. 13 Mar. 2016. http://www.sciencedirect.com/science/article/pii/S2090123213000969  
2. Bergin, J. "Contact Lens Polymers." Contact Lens Polymers. Apr 6. 2000. Web. 13 Mar. 2016. http://wwwcourses.sens.buffalo.edu/ce435/2001ZGu/Contact_Lens/ContactLensReport.htm
3. Coelho, K. "Disposal of Polymers." Disposal of Polymers. Sep 23. 2013. Web. 13 Mar. 2016. http://www.slideshare.net/karlcoelho/disposal-of-polymers
4. DePaolis, M. "Contact Lenses: Frequently Asked Questions." All About Vision. Web. 13 Mar. 2016. http://www.allaboutvision.com/faq/contactlens.htm
5. Kamat-Paranjupe, M. "Manufacturing Methods of Soft Contact Lens." Manufacturing Methods of Soft Contact Lens. Aug 31. 2013.Web. 13 Mar. 2016. http://www.slideshare.net/Eyenirvaan/manufacturing-methods-of-soft-contact-lens  
6. Kemsley, J. "Science & Technology: What’s That Stuff? Contact Lens Solutions" Chemical & Engineering News. Nov 17. 2008. Web. 13 Mar. 2016. https://pubs.acs.org/cen/whatstuff/86/8646wts.html
7. Marika, N. "Geography Life Cycle Assessment." Prezi.com. Nov 8. 2012. Web. 13 Mar. 2016. https://prezi.com/xd6ye8fmw4bu/geography-life-cycle-assessment/  
8. N/A. "Great News If You Wear Contact Lenses - RecycleScene." RecycleScene. 2012. Web. 13 Mar. 2016. http://www.recyclescene.com/how-to-recycle/plastic-contact-lens-cases
9. N/A. "How Are Contact Lenses Made" AC Lens. Updated Nov 2015. Web. 13 Mar. 2016. http://www.aclens.com/How-Contact-Lenses-Are-Made-c233.html
10. N/A. “Is Silicone a Plastic?” Life Without Plastic. c.2014. Web. 13 Mar. 2016. http://www.lifewithoutplastic.com/store/is_silicone_a_plastic
11. N/A. “Plastic Recycling” Wikipedia. Wikimedia Foundation. Updated Mar 12. 2016. Web. 13 Mar. 2016. https://en.wikipedia.org/wiki/Plastic_recycling
12.  Rastogi, N. "Are Glasses Better for the Planet than Contact Lenses?" Jan 12. 2010. Web. 13 Mar. 2016. http://www.slate.com/articles/health_and_science/the_green_lantern/2010/01/glasses_vs_contact_lenses.html
13. Segre, L. "Daily Disposable Contacts: A Healthy Choice for Eyes." All About Vision. Updated Sep 2015. Web. 13 Mar. 2016. http://www.allaboutvision.com/contacts/disposable.htm  
14. 14.  White, G. "Caring for Soft Contact Lenses." All About Vision. Updated Oct 2015. Web. 13 Mar. 2016. http://www.allaboutvision.com/contacts/caresoftlens.htm
15. Woodward, A. “Contact Lens.” How Products Are Made. 1996. Encylopedia,com Web. 13 Mar. 2016. http://www.encyclopedia.com/topic/Contact_lenses.aspx

Laena Otsuka

DES 40A

Cogdell

Embodied Energy Throughout the Lifecycle of a Soft Contact Lens

          Contacts lenses are thin lenses which sit on the surface of the eye in order to correct poor vision. Although contacts have been around for more than 100 years, soft lenses were not invented until 1959, when Czech chemists, Otto Wichterle and Drahoslav Lim, developed hydrogels necessary for the comfort and moisture of modern day soft lenses (Wichterle). In 1998, the first silicone hydrogels were released by Ciba Vision in Mexico. With this new combination of hydrogels, providing comfort, and silicone, with remarkable oxygen permeability, contact lenses because a viable option for many people. According to an annual report, nearly 125 million people and counting, 2% of the world’s population use contact lenses (Barr). With so many people wearing lenses, this begs the question of how much energy is being used to support this demand. This paper will trace the embodied energy throughout the lifecycle of contact lenses.

          Firstly, energy is required in the acquisition of raw materials. As stated, modern soft contact lenses are composed of hydrogel and silicone. Producing hydrogels requires ionization of high energy radiation, like gamma rays and electron beams. Though I was unable to find a specific quantity of energy, I can assume reliance on such high energy sources of power use quite a bit of power. As for Silicone, for every kilogram of Silicone produced, 230-235 MegaJoules are required to convert the primary energy source of hydrocarbons from fossil fuels into the raw material needed. Though I was able to find how much energy is required for silicone production, it quickly became clear that companies were not too eager to disclose information about where the raw materials they use come from, and how much energy they were using to acquire them. Despite efforts to reach out to manufacturers about their raw materials and the energy associated with them, this was the first roadblock in our research process.

          Next, the raw materials must be turned into contact lenses, requiring energy for manufacturing and packaging. To find out more about the energy going into these steps, I reached out to Johnson and Johnson, one of four main contact lens manufacturers in the United States. They self-reported that when manufacturing Acuvue Oasys lenses, they use energy from fossil fuels to power boilers in factories, electricity, and fleet vehicles. Soft lenses are crafted by a technique called “moulding,” by which molten hydrogel and silicone form a plastic like material, which is poured into a mould and spun at high speeds in a centrifuge (Federal Trade Commission). This allows mass production of perfectly smooth lenses, but requires the same high energy radiation as in the production of hydrogels and silicone. Most of the energy use in the manufacturing and packaging process comes from running such electricity powered machinery, as well as for producing enough heat for boilers. Though manufacturers appear hesitant to state the exact quantity of energy their factories use, they readily provide information on their reduction of energy use. For example, the Johnson & Johnson’s Jacksonville factory reported took measures such as improving energy efficiency of fume hoods, machinery, and boilers, as well as closely monitoring gas and heat usage. They began conservation efforts in 1999, obtaining a 7% reduction by 2010 under Kyoto protocol requirements (Nichols). Unlike other manufacturers, Bausch and Lomb reported that they used a total of 131 kWh of electricity in 2011, though they did not specify how the electrical energy was used. While we don’t know exactly how much energy these machines are using, we do know that a lot of energy is lost during the process. According to a 2012 study, the production of silicone hydrogel contact lenses have an energy loss of 27 to 40%, meaning that proportion of energy is not harnessed for use. This happens when materials deflect particles from their path of energy and are therefore lost. Therefore, there are still many remaining questions as to the actual quantity of energy used during the production and packaging of soft contacts, but we can assume it’s quite a bit.

          Next, I began to investigate the energy used during the transportation component of the lifecycle. Immediately, it was clear that the main source of energy usage in the distribution process is due to the use of fleet vehicles. Though this information was not made explicitly available, I traced my own contact lens purpose to deduce the energy usage during transportation. Because I only considered the energy required for the vehicle to drive from Point A to Point B, it can be assumed that the actual energy consumption is even greater when accounting for other, less significant steps. So, I ordered Acuvue Oasys contact lenses from 1800Contacts.com. My order began in Jacksonville, Florida, 2,800 miles from Davis, California. This was the nearest distributor to me, as the other factories are in Brazil, UK, and Singapore. According to the Environmental Protection Agency, a semi truck would get about four to eight miles per gallon, meaning this would require 11,000 to 22,000 gallons of gasoline. According to their formula, though there is debate surrounding its accuracy, 33.7 kWh are required to produce one gallon, meaning this trip took nearly 380,000 kWh to get to my apartment in Davis, California. Though the actual amount of energy varies greater depending on what vendor contacts are ordered through, proximity to destination, and actual gas mileage of the truck, the energy usage from fossil fuels are significant in this step of the lifecycle.

          The energy component for usage is not quite relevant when discussing energy. When the contact lens reaches the consumer, the lens it opened from the blister package, and stored in a plastic case with contact solution. It is worn in the eye, and cared for and disposed of according to the type of lens. Some lenses are daily, monthly, quarterly, or even annually renewed. If energy had to be discussed for this portion, caloric energy required to actually use the product could be considered, though this would be overkill in my opinion.

          Next, the consumer finishes using the contact lens, and the waste associated with lenses and its accessories are disposed of, some of it as recycling. Although lenses can’t be recycled, and must be thrown away with regular trash, the bottles, boxes, and packaging can be. It’s reported that the average contact lens user, and globally there are 125 million contact lens users, uses up to 15 500 mL bottles of contact solution per year. That’s 1,875,000,000 PET bottles needing to be recycled! If 25 empty 500 mL PET bottles weight 18 grams, that means 1.9 billion bottles weigh 1,350 tonnes annually. If it takes 3047.94 kWh to manufacture products from a ton of recyclables, that means recycling these bottles into new products requires 4,115,719 kWh. Again, I found that Recycling facilities were not willing to provide information on the amount of energy they use, but only on how much they’ve saved due to recent efforts. However, I must assume that the municipality trucking, maintenance, storage, and manufacturer energy use of employees, material transporting, preparation, storage, and processing take up energy. After all, I know that one factory (Using Bausch & Lomb) recycles 510,000 Kg of waste annually, but this information is not incredibly useful because different types of waste are more or less easily recycled than others, requiring different amounts of energy.

          What cannot be recycled, the plastic blister packaging and the contact lens itself, is sent to a landfill for disposal. Not surprisingly, I was unable to find information on exactly how much energy landfills require to process plastic in landfills. Again, it seems Manufacturers and Waste treatment facilities all redirect questions of energy usage to information on energy saved, which I interpret as them avoiding negative attention towards their environmental contributions. From what information I could find, the actual energy consumption during waste treatment is not significant. Though a person uses up to 730 lenses (if they were daily disposables), this would only produce about 9.125 grams of plastic, roughly the weight of two plastic credit cards. They are not a significant contributor to waste, and thus not a large contributor to energy usage required to treat waste. I assume the impact might not be too horrible, as hydrogels as a raw material are sometimes even used to retain water in landfills and help break down other garbage. To find more specific information, I began to see what manufacturers had to say about the waste produced by contact lenses and their packaging. Bausch & Lomb, one of the major contact lenses manufacturers, claims to be dedicated to reducing overall usage and waste. In their yearly sustainability report, they provide an impressive list of achievements such as reducing “hazardous waste generation by 90% by eliminating a solvent from the manufacturing process, improving the recycling program for electronic waste, and implementing a single stream” (Bausch). Since 2008, they reduced utility provided electricity by 21%, water by 24%, and generated 61% less hazardous waste. They recycle 17% more, though there has been no reduction in fossil fuel consumption or non-hazardous waste generation. This, at least marks a positive trend in the reduction of energy use, even if it is unclear exactly how much energy goes into waste management.

          In conclusion, the embodied energy throughout the lifecycle of a soft contact lens is not clear or simple. Though I can make assumptions about some of the steps in the lifecycle, this appears to be a product which has not been well researched at this point. I think that one reason for the lack of information surrounding energy use is because manufacturers often receive negative publicity for using large amounts of energy, whether or not they are significantly larger than competitors. On the other hand, they understand the positive impact taking steps to publicly establish themselves as friends of the environment, and are able to manipulate information they want to give in order to seemingly answer the real questions.

Bibliography

1. Barr, J. "2004 Annual Report". Contact Lens Spectrum. January, 2005.

2. Bausch & Lomb. "Environmental Sustainability Report." ENVIRONMENTAL SUSTAINABILITY

REPORT: Letter from the CEO. Bausch & Lomb. Bausch & Lomb Incorporated, 2012. Web. 1 Mar. 2016.

3. "Caring for Soft Contact Lenses." All About Vision. Web. 14 Mar. 2016.

4. "Contact Lens." How Contact Lens Is Made. Web. 14 Mar. 2016.

5. CIBA. "Health, Safety, and the Environment." CIBA Vision 1 (2009): 1-100. Print.

6. Egerton, R. F. "Electron energy-loss spectroscopy in the TEM". Reports on Progress in

          Physics. 2009.

7. "FACILITY AUTOMATION SOLUTIONS." Facility Automation Solutions — Jacksonville,

          Florida. BroadBased Communications, Inc., 2009. Web. 14 Mar. 2016.

8. FDA Premarket Notification for "new silicone hydrogel lens for daily wear" 'July 2008.

9. Federal Trade Commission. "The Strength of Competition in the Sale of Rx Contact Lenses: An

          FTC Study". February, 2011.

10. Hiti, K. "Viability of Acanthamoeba after exposure to a multipurpose disinfecting contact

lens solution and two hydrogen peroxide systems". British Journal of Ophthalmology. 2002.

11. Hutchinson, Alex. "Is Recycling Worth It? PM Investigates Its Economic and Environmental

Impact." Popular Mechanics. Hearst Communications, 13 Nov. 2008. Web. 14 Mar. 2016.

12. "Hydrogel: Preparation, Characterization, and Applications: A Review."Hydrogel: Preparation,

Characterization, and Applications: A Review. Web. 14 Mar. 2016.

13. Intagliata, Christopher. "Does It Cost More to Recycle a Plastic Bottle than to Make a New

          One?" Scienceline. NYU, 5 May 2008. Web. 14 Mar. 2016.

14. Liu, Ronghua. "Patent US 8481662 - Silicone Hydrogel Contact Lenses Having Acceptable Levels of Energy Loss." Google Books. Coopervision Inc., 9 July                 2013. Web. 14 Mar. 2016.

15. "Looking at Silicone Hydrogels Across Generations". Optometric Management. Retrieved March 5, 2009.

16. Morgan, Philip B., "International Contact Lens Prescribing in 2010". Contact Lens Spectrum. October 2011.

17. Nichols, Jason J., "ANNUAL REPORT: Johnson & Johnson Contact Lenses 2010". January 2011.

18. Wichterle O, Lim D."Hydrophilic gels for biological use" (117–118). 1960.

Marisela Estrada

Professor Cogdell

40A

14, March 2016

Soft Contact Lenses – Waste

           Soft contact lenses are a thin small plastic that floats on the surface of an eye to correct visions or for cosmetic purposes to enhance and change the eye color. They have made life easier for many people around the world who for example practice sports and are therefore able to see a full field of unobstructed vision (Segre). In 2004, it was estimated that 125 million people (2%) use contact lenses worldwide, including 28 to 38 million in the United States. In 2010, worldwide contact lens market was estimated at $6.1 billion, while the U.S. soft lens market was estimated at $2.1 billion (Nichols). The purpose of this essay is to go through the life cycle of the soft contact lenses and address how each cycle of extraction of the materials, and production process of the product contribute to climate change and large amounts of waste that affect our environment.

           The first step of the life cycle of the soft contact lenses is the raw materials acquisition. This cycle digs into the materials needed in order to make the product. The raw materials used to make soft contact lenses are plastics called Poly Hydroxyethyl methacrylate (pHEMA), that contain nitrogen atoms in its structure and have hydrophilic (“water-loving”) qualities that soak up the water to keep their shape and optic functions (Woodward). The Polymers constitute of multiple monomers such as N-vinyl pyrrolidone (NVP), Methacrylic acid (MA) and Poly-2-hydroxyethyl me-thacrylate (polyHEMA) that are linked together to create Silicon Hydrogels (Ngakhushi). Which is the material used to create soft contact lenses that increase in oxygen permeability that allow the lenses to be used for extended wear without making damage to the eye. “The process of combining these monomers has been linked to efforts of combining oil with water while maintaining optical clarity” (Dumbleton). The extraction of the crude oil to fabricate Polymers (plastics) continue to damage the drillers and the environment by spills and releasing toxins into the atmosphere that are dangerous for the human being and the ecosystem.

           This process is done by pumping the liquid oil out of the ground by using drilling rings which may result in large oil spills that occur “during the process of drilling, transport, and use, which of course affect the surrounding environment” (Spooner). At the refinery the hydrocarbons in the oil are broken down into smaller ones, in order for the petrochemical plat to obtain the monomers they need to create polymers through chemical reactions. Then the plastics factories modify the polymers in forms of resins to the final product. “The top oil-producing countries are Saudi Arabia, Russia, the U.S., Iran, China, Canada, and Mexico. Together, these countries produce more than half of the total oil resources in the world” (Spooner). Causing global warming and other harm to our environment. Although the “…plastics industry has worked hard to reduce energy and water use, as well as waste generation during the manufacturing process” (Spooner), our environment continues to be affected by the extraction of the raw materials and manufacturing of such products.

          The packaging for the soft contact lenses is yet another cause of global warming and it’s due to the extraction of the raw materials, fabrication and waste of cardboard, plastic foil and saline that is produced at the manufacturing place containing the contact lenses. Similar to the process of polymers, some of these materials follow the same path. The raw material for aluminum foil is aluminum which is produced mostly in China as well as Canada, Australia and Russia. In order to run these factories energy is needed, which results in greenhouse gas emissions, affecting our eco system.

          The second cycle of the life cycle of the soft contact lenses is the manufacturing and processing of the product. There are three primary ways in which contact lenses are manufactured; spin casting, lathe cutting and by cast molding. “Soft contact are typically formed using cast molding or the spin cast method” (Bergin). They can also be produced by using the lathe cutting process, but it is less common to do so. All leaving residue behind that builds up in the land field and our rivers.

          In the spin casting method, the liquid is placed in a mold that is being rotated where it is being polymerized. This method is effective due to the lens optics being varied by the speed of rotation as well as the shape of the mold (Bergin). This is where the centripetal force forms an aspheric base curve as well as a front curve formed by the curvature of the mold. “Production by spin casting technology is much more productive [and cheaper] than lathe cut, but certain of waste lenses is always a problem in spin casting” (Petherick).

         Lathe cutting is very time consuming and it takes intensive as well as expensive labor which is why it is difficult to reproduce, since each lens is individually made. The diameter of the buttons are about 12 to 15mm and 4.5 inn thickness for the machine to cut (Paranjape). It is then reduced to a 2.5 thickness leaving residues of the buttons and wasting high energy by operating the machines. As well as other materials to rinse, quality control check and seal.

         However the cast molding method is a more effective and popular form of manufacturing. The first step is to cast the mold where the monomer could then be polymerized. Here “the lens parameters are varied by changing the shape of the anterior and posterior molds” creating high quality lenses (Bergin).  It produces a lens without the need to polish at a lower cost than any other process, maintaining a smooth surface. However the cast molding is prone to leave scars on the lens itself and its productions creates waste in the making of molds.

         The mass production of plastics that go into the pair of contact lenses and the packaging for the soft contact lenses also builds up the amount of waste. A year's worth of daily lenses make a total of 360 pairs that produce 3 pounds of plastic, between the lenses themselves and the blister packaging (Rastogi). “Twelve pairs of monthlies, with 12 carrying cases and 12 bottles of cleaning solution, produced 2.5 pounds. (That is also) tallied the metals to seal the blister packs and the paper used in the boxes and instructional leaflets” (Rastogi). “By comparison, the average American generates an annual total of more than 1,600 pounds of garbage (PDF)” (Rastogi). Therefore the amount of waste produced after the production of the soft contact lens and by the end consumer are insignificant when compared to the amount of waste that we generate in our everyday life. However it contributes to the harm of our environment.

         The third step of the life cycle for the soft contact lenses is the distribution and transportation of the product. The soft contact lenses have a long way starting from the raw material itself to the store. “Acuvue Contact Lenses are sent to over 70 countries worldwide and Australia is one of them” (Marika). The contact lenses that are via shipped or air cargo are sent out using natural resources such as fuel for transportation that contribute to the climate change. An example of exportation and total waste of fuel would be from Limerick, Ireland where the contact lenses would be manufactured and then transported to Australia. Traveling 3838 nautical miles using a total of 7112. Liters of fuel to travel across, affecting the climate change. Local transportation also adds up to the contribution of climate change by burning high amounts of fuel to deliver the product to our homes and local pharmacy’s.

           The fourth step of the life cycle for the Soft Contact Lenses is the use, re-use and maintenance. This cycle describes what happens to the product in the hands of the consumer. First the consumer would have the option to choose between the multiple kinds of lenses between daily disposable ones or others that last for longer periods of time. Depending on the type of lens, the use of solution for daily maintenance would apply. Having to use contact lenses can be expensive especially when it comes to having to replace and maintain the lenses and the solution bottles. This also creates a large amount of trash at the end of the cycle of the product that end up in the land fields. Some of which take up the land and affect living situations for the community.

           The fifth step of the life cycle for the soft contact lenses is recycle. This cycle describes when the consumer turns in the product to the recycling center. Unfortunately there is no specific place for the breathable polymer to be recycled, although it ca be used in crafty ideas (Green24). However the packaging will usually be recycled. It displays an identification with a recycling code that allows the consumer to identify if their solution bottle or packaging is made out of a plastic that is recyclable (Green24).  Recycling the polymers reduces the disposal problems as the amount of crude oil use to fabricate them. The downside to this is the fact that before the recycle process the multiple kind’s polymers must be separated from each other. Which can be very difficult and expensive. “Most types of plastics are not biodegradable and are in fact extremely durable, and therefore the majority of polymers manufactured today will persist for at least decades, and probably for centuries if not millennia” (Hopewell). “As a consequence, quantities of end-of-life plastics are accumulating in landfills and as debris in the natural environment, resulting in both waste-management issues and environmental damage” (Hopewell).

         The last step of the life cycle for the soft contact lenses is waste management. This is where the material ends up in the land field. In this cycle the polymers, the raw material of soft contact lenses and its packaging which were not recycled end up getting buried. “…Wasting energy and leading to serious habitat destruction” (Coelho), or getting burn which produces carbon dioxide and other pollutants to be released up into the air adding to global warming. However it is in this process where some of the plastics are recovered when they are easily spotted in the land field due to their nature of flexibility and lightweight mass. Then they are taken back to the factories where they can recycle the polymers and give them a new purpose.  

          This concludes the life cycle of the soft contact lens and how the extraction of the raw materials and fabrication has a significant influence to the global warming and climate change of our planet. Even though the life cycle of the product leads to the creation of trash and unwanted material, there are multiple ways in which someone can participate to protect our environment. That is disposing of the after use of plastics in the proper recycling bin for the factories to properly break down and shape back into a new product. As well as to switch to other types of contact lenses that don’t require as much as maintenance or replacement. In addition, some argue that eye glasses are much more sustainable than plastic, though there is some controversy as to if glasses really use less plastics than contact lenses and their required accessories.

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