Ask Pablo: What Is More Sustainable: Eyeglasses Or Contact Lenses?
Contact lenses are disposable, a word that is not usually synonymous with sustainability. But eyeglasses are made out of metal and other materials that also have a certain environmental footprint. Which is the more sustainable choice?The Environmental Impact Of Eyeglasses
Assuming an average replacement rate of three years or more, eyeglasses are considered a durable good. Once they have been produced there is no incremental impact associated with their use (unless you use disposable lens wipes) but their manufacture, transportation and end-of-life must be considered. Eyeglasses are typically made with metal and/or plastic frames and the eyeglass lenses themselves, despite their name, are commonly made from acrylic plastics. The raw materials for these metals and plastics must be extracted from the earth (unless they are recycled), extensively processed, and transported over great distances. After this, the manufacturing of the frames and lenses probably has a minimal, but not negligible, impact. A final consideration must be made for the end-of-life for your eyewear. If you donate your eyeglasses they are likely to find many more years of use, and therefore spread out their impact over a larger number of years.
The Environmental Impact Of Contact Lenses
Contact lenses are disposable, most of them intended to be replaced at least monthly. That means 36 pairs of contact lenses are required to last you as long as the one pair of eyeglasses. While the contact lenses themselves are made out of a nearly negligible amount of plastic, the disposable containers that they are delivered in consist of a significant amount of packaging. Add to this several bottles of saline solution, all of which needs to be produced, packaged and shipped to the consumer. As we know, shipping weight can have a significant impact on a product's supply chain greenhouse gas emissions, and few things have as much shipping weight per unit as products that are shipped in, or otherwise contain a large proportion of water (think beer and wine).
So Which Is It? Eyeglasses Or Contact Lenses
Without more exhaustive life cycle analysis studies of eyeglasses and contact lenses it is hard to say at which point eyeglasses become environmentally preferable to contact lenses but my professional opinion is that it is much sooner than the expected three-year lifespan of the eyeglasses. Of course, many of you will comment that you have been wearing the same pair of glasses since Jimi Hendrix was still with us. Maybe they are decades out of style, but for those of you that are waiting for them to come back into fashion, good for you. Just, for the sake of your fellow drivers, please make sure that your prescription is current.
Pablo Paster is a weekly columnist for TreeHugger.com and Prinicpal Environmental Consultant at Hara Software. Send your questions to Pablo(at)TreeHugger.com or submit the via this form and connect to his RSS feed.
More TreeHugger Articles On Eyeglasses:
Adspecs Eyeglasses Could Provide Sight for a Billion
TED Talk: Josh Silver Demonstrates Ultra-Utilitarian Liquid-Filled Eyeglasses
Modo Breaks Out New, 95% Recycled Eyewear. But Are We Impressed?