I am a contact lens wearer, and have for the last 7 years or so opted for daily disposable soft contact lenses. I had previously used monthly disposables for about 7 years, and non-disposable (yearly) contacts for about 3 years. Therefore, I estimate I have gone through about 5,300 individual lenses over the course of my lifetime.
Over the past week, I have been trying to come to a conclusion regarding which type of lens is the least harmful for the environment. While it might seem clear that wearing glasses is probably the best alternative, several reasons converge to make the quality of vision I achieve with glasses unsatisfactory for my daily activity. In consequence, I believe that (at least for the time being), giving up on contact lenses is not an acceptable choice.
When comparing lens-replacement schedules, it is immediately obvious that using daily disposables consists of throwing out an (albeit small) amount of plastic (1) every day; however, there is no need to use any kind of cleaning solution, nor the (much larger) plastic containers those solutions come in, or the several sets of lens cases one ends up using when wearing longer-term contacts.
On the other hand, in terms of the manufacturing-associated footprint, using 730 lenses per year must surely be worse than discarding just 24 (and, obviously, much worse than using just 2). However, one must once again take into consideration the manufacture process that goes into the production of the cleaning solutions, the respective bottles, labels and packaging, and the lens cases.
Morgan, Morgan and Efron have actually calculated the environmental impact of three contact lens replacement schedules (“conventional” non-replacement, monthly and daily replacement), and published their results (2) in “Contact Lens & Anterior Eye”, the peer-reviewed Journal of the British Contact Lens Association, concluding that “the overall environmental impact of waste generated (…) by the end consumer is insignificant (0.5%) compared with the amount of waste generated in our everyday life” and that “conventional lens wear had the highest impact and (…) [monthly disposable] had the lowest impact”.
Going back to my calculated use of 5,300 lenses over the last 17 years, and if I guesstimate an individual dry-weight of about 10-20 milligrams, I will have thrown out just 50 to 100 grams of contact lens plastic (plus the weight of all plastic containers associated with the use). Nevertheless, the fact that the impact of contact-related waste is described by the Morgan et al as “insignificant” should not be interpreted as a positive aspect of contact lenses, but rather as a relative consequence of the enormous amount of non-contact-related waste produced by men.
(1) Corresponding to the lens itself and the container. And, at least in the case of the brand I use, a small amount of foil that seals each lens inside its moist little container (a blister-pack).
(2) “Environmental impact of three replacement modalities of soft contact lens wear”, 2003, volume 26, issue 1, pages 43-46.