Lenses used in vision correction have evolved from the initial glass reading stone of the 10th century to the currently anticipated planar metalens made from "nanopillars" of titanium dioxide. With ideas from early scientific minds being translated into reality, and military commissioned concepts adapted for civilian use, spectacle lens and contact lens materials have progressed significantly over the last century, with the expectation of further lens material innovations ahead. The purpose of this article is a review of literature on the historical developments and advances in spectacle lens and contact lens materials.
Background: Climate change is a global challenge requiring mitigation from all economic sectors. Although the consequences of climate change are well documented, there are limited studies regarding greenhouse gas emissions generated by the optometric industry.Aim: This study explored the greenhouse gas emissions created from the freight-related distribution of spectacle and contact lenses to South Africa (SA) in 2019.Setting: Spectacle and contact lens distributors in SA and an optometric courier service in KwaZulu-Natal.Methods: Data from a survey completed by lens suppliers and a courier service provider in SA were used in a standardised emissions calculations tool.Results: The results indicate significant greenhouse gas emissions generated from the distribution of lenses in SA, which is of concern for climate change alleviation goals.Conclusion: It is recommended that practitioners in the optometric industry, and other healthcare service providers, calculate their emissions data, modify practices to support climate change mitigation and be cognisant of the effect of their practices on the environment.
Background: Global population growth and ageing are factors that contribute towards an anticipated increase in the usage of spectacles and contact lenses for vision correction. The subsequent disposal of polymeric vision corrective devices currently, has uncertain environmental impacts.Aim: The purpose of this study was to explore potential environmental impacts and end-of-life (EOL) pathways of a sample of polymeric spectacle lenses and through the use of analytical chemistry processes.Setting: Laboratory analysis of ophthalmic lenses.Methods: Inductively coupled plasma–optical emission spectroscopy (ICP–OES), elemental analysis and calorific value investigations were conducted on a sample of spectacle lenses and contact lenses.Results: Metal ion analysis by ICP–OES confirmed the presence of manganese in all the lenses and chromium in two of the 13 contact lenses. All of the lenses had over 42% carbon while calorific values of up to 32.40 MJ/kg and 23.31 MJ/kg were found in the spectacle lenses and contact lenses, respectively.Conclusion: Further investigation is required regarding the presence of chromium in two of the contact lenses. In general, lenses are likely to remain as solid waste in landfills depending on the disposal conditions. Considering their calorific values, lenses would be useful in incineration with energy recovery processes however the suggested ideal EOL route would be the implementation of lens recycling, through non-toxic and green chemical processes, to retain material value and promote a circular economy.Contribution: This study provides new information on the environmental consequences of current modes of lens disposal and suggests EOL alternatives thereof.
Background: The increase in global plastic waste generation poses a threat to human, animal and plant life. As such, industries world-wide are encouraged to review waste management systems to prevent, minimise, recycle or recover plastic waste. There is a paucity of information on plastic waste generation by the local optical industry in South Africa, especially with respect to spectacle lens and contact lens recycling.Aim: The purpose of this review article was to provide a current outlook on spectacle lens and contact lens recycling in South Africa.Methods: Literature review of scientific papers from online databases, websites and lens material patents.Results: No studies regarding lens recycling in South Africa were found. However, data for this review were collated based on lens constituent materials.Conclusion: This review article provided an overview of lens recycling, identified the barriers and potential measures to advance plastic spectacle lens and contact lens recycling in South Africa, and suggested controlled energy recovery as an alternative pending implementation of lens recycling programmes.Contribution: This paper contributes useful information on a previously unexplored aspect of recycling in South Africa. Ophthalmic lens recycling is currently not available in South Africa, and as such, this review focuses on the current outlook, barriers and considerations for implementation of such programmes.
Background: The increase in global waste generation has adverse impacts on the environment. Significant volumes of waste are generated in the lifecycle of spectacles, contact lenses (CLs) and associated products, and there is a lack of published data on their disposal practices.Aim: To determine optometrists’ recommendations to their patients, and lens wearers’ practices regarding the disposal of ophthalmic lenses and associated lens products.Setting: Optometrists and lens wearers in South Africa.Methods: Surveys were distributed via online platforms to optometrists and lens wearers and paper copies of the surveys were also available. Data from both surveys were analysed using IBM SPSS version 24.Results: Responses from 353 optometrists and 603 lens wearers were analysed. Optometrists were highly likely to recommend that patients should discard their old spectacle lenses (24%), and used CLs into wastewater systems (10%), or make no recommendations on either, respectively, (16%, 12%). Lens wearers were highly likely to retain their old spectacles upon new purchase (57%) and dispose used CLs into wastewater systems (37%). Less than 20% of optometrists and lens wearers were highly likely to recommend and engage in recycling of associated ophthalmic products.Conclusion: The disposal of CLs into wastewater systems, which contributes to microplastic pollution, must be highlighted and avoided. Optometrists should incorporate disposal instructions with all products sold to patients and promote recycling. Lens wearers should also be mindful of the environmental impact of their disposal practices.Contribution: This study provides previously unknown data on ophthalmic lens disposal practices in South Africa, and emphasises the need for environmental awareness.
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