Ophthalmology Going Greener: A Narrative Review

Ophthalmology has the highest surgical volumes and rapid turnover rates in the NHS with approximately 414,000 cataract procedures in England and 20,000 in Wales between the years 2017 and 2018 [19]. This makes cataract procedures an obvious target for reduction of carbon emissions. Morris and colleagues estimated the carbon burden accounting for 343,782 cataract procedures in England in 2011 to be at least 63,000 tonnes of CO₂ equivalent (CO₂eq) taking into consideration building and energy use, travel and procurement [20]. Somner et al. compared different techniques of cataract explantation [phacoemulsification vs. modified small incision cataract surgery (MSCIS)] and the environmental impact. They concluded that phacoemulsification is not only much more costly but has a significantly greater environmental impact compared to MSCIS. This is the result of disposable waste (paper and plastic) and the energy used by the phacoemulsification machine [21, 22]. In terms of cost-effectiveness, various studies carried out in India and Nepal have shown that the technique of MSICS is 1.4–4.7 times less expensive than phacoemulsification with similar visual outcomes and complication rates. It is therefore the predominant technique in developing countries and areas with limited resource but high volume and backlog [22‐26]. Of course, in many developed nations there are different socioeconomic conditions and healthcare infrastructures and expectations, and larger ‘real-world’ prospective analyses would be required to assess the long-term visual outcomes of different cataract surgery techniques, their carbon footprints and cost–benefit analyses.

In developed countries, single-use disposable instruments and equipment have contributed to a mass production of clinical and non-clinical waste, and significantly to carbon emissions. Morris et al. estimated that 53.8% of these emissions were from procurement, the majority due to disposable medical equipment [19]. Goel and colleagues published data on productivity, costs, carbon emissions and waste generation for every cataract surgery performed across nine participating sites internationally, using the “Eyefficiency” cataract surgery auditing tool. Service costs range from £31.55 to £399.34, solid waste weighs between 0.19 and 4.27 kg and carbon emissions range from 41 kg CO₂eq to 130 kg CO₂eq for each cataract case performed. Comparing the expenditure of medical supply and waste generation between two developed countries exposes an interesting difference. New Zealand has the highest expenditure on consumables with low waste generation indicating that the supply spending could be disproportionately high. The UK spends moderately on their disposable supplies but generates twice as much waste compared to that of the next highest site, indicating that packaging and waste management could be an issue [27].

Figure 1a shows an example of non-clinical waste generated in a cataract centre in the UK in preparation for a cataract case and Fig. 1b shows an example of clinical waste generated upon completion of a cataract case. During a non-complex phacoemulsification case, a total of 2.10 kg of waste was generated. It is important to recognise the amount of waste produced from each case depends on various factors such as the complexity of case (meaning more or less surgical equipment), the use of disposable equipment and packaging, the number of saline bottles used and the remaining volume of balanced salt solution, the number of surgeons operating affecting disposable gowns and gloves used.

By comparing UK cataract services with the Aravind Eye Care System (AECS) in India, notable differences in carbon generated are observed. At the AECS approximately 6 kg CO₂eq is generated per phacoemulsification procedure compared to approximately 130 kg CO2eq in the UK, for every case performed [20]. This significant difference is due to the Aravind’s high volume approach providing up to 1500 cataract surgeries per day, thereby minimising the environmental footprint associated with electricity and energy use. They also reuse surgical gowns, blankets and certain surgical and pharmaceutical supplies (including multiuse solutions during cataract surgery and preoperative eyedrops). Contaminated instruments (instrument trays and phacoemulsification tip) would be sterilised in between each case, whereas non-contaminated instruments (fluid collection bags, plastic protectors on phacoemulsification machines and tables, intraoperative pharmaceuticals) would be sterilised at the end of the operating day to reduce environmental impact associated with repeated sterilisation. Despite reusing surgical supplies, cleaning gloves with alcohol and chlorhexidine, and simultaneously operating on multiple patients within a single operating theatre, the rate of postoperative endophthalmitis is no higher than European norms [28, 29]. However, because of stricter infection control guidelines, implementation of the Aravind model of practice is not currently feasible in countries such as the UK.

The 5 R’s of sustainability (Reduce, Reuse, Recycle, Rethink and Research) can be applied to reducing the environmental impact of ophthalmic surgery in a cumulative manner, whilst maintaining patient safety.

We can reduce energy consumption by simply turning off lights in operating theatres and switching off equipment when not in use. The use of light emitting diode (LED) lights, timer and motion detectors will also result in significant reduction in energy expenditure [30‐32]. According to Kagoma and colleagues, operating theatres are almost always unoccupied up to 40% of the time over a 24-h period [33]. The Providence St. Peter Hospital, Washington reduced energy consumption by reducing its ventilation system output by 60% during unoccupied times [34].

Sensible ways to reduce the amount of waste generated should also be considered. Referring again to Fig. 1a and b, a major contributor to waste is plastic packaging, with the majority of the equipment being placed in plastic containers and double wrapped. The use of polypropylene plastic blue sterile wrap is not only damaging to the environment but will also concur a substantial disposal cost. There is an opportunity to work with industries to reduce the amount of waste derived from a single operation [33]. Understandably, ophthalmic surgeons have specific equipment they prefer for a certain surgical procedure, hence the existence of single packaging disposable surgical equipment, individually packed gloves and gowns according to size. Perhaps the creation of a surgeon-tailored pack with preferred equipment, gloves of their size and disposable gowns could reduce the amount of double packaging of each product.

Bartl [35] suggested that the reuse of materials is equally as effective at reducing waste as it avoids the side streaming of waste generated through recycling and occurs before the end-stage of material is reached. Kwakye and colleagues reported that switching from disposable to reusable surgical gowns in a single hospital led to a waste reduction of 23,000 kg of carbon, saving the hospital 60,000 USD over a 12-month period [36]. In a review article published by Guetter in 2018, decisions whether to use disposable or reusable materials such as drapes and surgical gowns are based on available scientific data and cost based on region, country, culture and customs. Data relating to infection rates is still controversial and more comparative studies are needed to look at savings and expenditures relating to reusable items [30]. Indeed, one can argue that the environmental impact of laundering of reusable textiles could potentially be more significant, especially when paired with harmful laundry chemicals and inefficient ageing hospital infrastructure (water and energy). The benefits of reuse of surgical equipment are also disputable because of the hidden costs associated with storage, damage of equipment in the process of sterilisation and instrument handling, and the risk of cross-contamination e.g. Creutzfeldt–Jakob disease (CJD), especially in vitreoretinal surgery when neural tissues are involved [37].

According to Southorn et al. [38] each operating room has the potential to produce up to 2300 kg waste every year, with almost 80% of the total waste generated preoperatively. This is variable depending on the surgical specialty, type of procedure, duration of surgery and surgeon preference of instruments and equipment. The amount of waste generated also differs from one country to another, more so in higher income countries [32]. Waste segregation is important especially in healthcare not only from an ecological standpoint but also economical one as clinical waste is the most expensive to treat [30].

As of 2013, a meaningful recycling programme has taken place in about 80% of Australian hospitals, about 50% in the USA but less than 10% in the UK [32]. This difference may be due to varying abilities to segregate waste because of strict infection control rules and fear of contamination, leading to incineration of potentially recyclable items [38]. In a survey published in 2012, only 11% (n = 780) of participating anaesthetists from Australia, New Zealand and England agreed that adequate recycling occurred in their theatre [39]. Of course, recycling also comes with its cost; the impact of carbon emissions from collection, sorting and reprocessing needs to be considered. Furthermore, a significant proportion of recycled paper, scrap metal, with approximately 70% exported to China and Hong Kong in 2016, led China to impose a ban on waste imports. This raises questions about sustainability of recycling [32, 35]. In 2015, McGain and colleagues published a cohort study reporting that recycling did not lead to additional costs and that the overall impact of recycling (although savings may be small) may be magnified if adapted by the national healthcare system [40].

‘Green initiatives, incentives or awards’ may encourage surgeons and administrators to rethink the global and financial impact of the unnecessary waste produced [31]. Perhaps ophthalmologists can be invited to participate in an innovative competition to design a surgeon-tailored instrument pack based on each subspecialty in ophthalmology to best cut down unnecessary waste and cost, whilst maintaining patient safety.

As pre-existing literature on environmental impact on current ophthalmic practices is scarce, more research and publications are needed to help map out the carbon footprint of various eye care services especially relating to cataract surgery and glaucoma care in the community [7]. More data is needed on environmental impacts of healthcare activities, life cycle analysis of materials, and cost analysis. Innovative design of devices that minimise environmental impact whilst maintaining standard of care would also be useful [33].

As large quantities of greenhouse gases are generated by patients travelling to access hospital-based healthcare, smaller treatment centres or screening hubs for patients with chronic eye conditions like AMD could be established peripherally in a number of locations, reducing transport-associated carbon emission. The challenge associated with delivering care in this way is the initial investment required, especially when such schemes may not offer a financial saving [51]. As the NHS moves to a population-focused planning and delivery of healthcare through the Integrated Care Systems there is an opportunity for such services at a regional level. Furthermore, an upskilled optometry workforce provides the opportunity for care to be delivered from optometry practices already located across towns, cities, and suburban areas offering convenient and closer-to-home locations. This approach again aligns with the NHS England care closer to home strategy, providing a number of benefits not least the reduction in patient miles. Many community optometrists have taken up training to provide extended care services to patients, allowing continuing professional development for particular clinical interests, whilst offering additional income generation under their NHS contracts. Nationally, optometrists who specialise in certain areas of ophthalmology and ophthalmic specialist nurses are already undertaking outpatient appointments and intravitreal injections respectively. These new models of care would provide care closer to where patients live and often located by public transport routes with opportunities to walk or cycle, thereby significantly reducing patient miles.

The use of teleophthalmology and health information technology can help save time, energy and raw materials like paper and plastic and their subsequent impact on the environment and our planet [52]. The collaborative effort of the Teleophthalmology Network in Scotland is one example of this approach. By supporting optometric practices to utilise smartphones attached to slit lamps, enabling ocular biomicroscopic videography, ophthalmologists are able to view a patient’s examination features in real time without the patient attending, thereby streamlining the ophthalmic triaging system [53]. Purohit and colleagues published a systematic review targeting transport-associated emissions and found that the carbon footprint saved using telemedicine ranges between 0.7 and 372 kg CO₂eq per consultation [54]. Sharafeldin and colleagues undertook a review on economic evaluation that supports evidence of cost-effectiveness of teleophthalmology on chronic conditions like diabetic retinopathy and glaucoma [55]. An audit carried out in Western Australia consisting of 709 patients found that they were able to correctly diagnose 95% of patients via remote consultations and saved over 10 days of outreach clinics for 287 patients with cataract seen and managed [56]. The use of teleophthalmology or virtual consultations have exponentially increased during the COVID-19 pandemic, to provide outpatient appointments in a way that usual change management cycles would have taken significantly longer to achieve. Although this was not suitable for all patients and types of appointment, it helped keep in-person hospital attendances to a minimum, whilst reducing patient miles travelled. Older patients may struggle with the not-so-traditional way of healthcare provision and the initial learning curve of telemedicine. Obtaining accurate visual acuity and clinical examination for future comparison may be difficult and is no substitute for face-to-face clinical examination. Nonetheless, with the advancement of technology, teleophthalmology offers an opportunity to deliver some suitable services remotely and provides a way to reduce the carbon footprint of services whilst allowing access to care in geographically isolated areas [57, 58].

The emergence of a variety of home devices for the monitoring of visual acuity, visual fields, and intraocular pressure for conditions such as diabetic retinopathy, AMD, and glaucoma also present as a movement away from traditional clinic visits and towards sustainability [59‐63]. In particular, ForeseeHome™ (conducts preferential hyperacuity perimetry for monitoring AMD) [64], myVisiontrack™ (uses shape discrimination hyperacuity testing in AMD and diabetic retinopathy) [65], and Alleye™ (detects neovascular AMD and distinguishes between dry and wet AMD) [66] are US Food and Drug Administration (FDA) approved platforms for monitoring patients. Integration of these applications within existing monitoring programmes could help in substantially reducing carbon footprints.

The application of artificial intelligence (AI) approaches such as deep learning (DL) to ophthalmic imaging, including digital fundus photographs and visual fields, has been reported to achieve high accuracy in automating the screening and diagnosis of common vision-threatening diseases including diabetic retinopathy [67‐69], glaucoma [70‐72], AMD [73, 74], and retinopathy of prematurity (ROP) [75]. A DL algorithm system developed by Abramoff et al., IDx-DR, has received FDA approval since 2018 for the detection of more-than-mild diabetic retinopathy in adults without physician-assisted interpretation [76]. Combining the use of ‘imaging hubs’ and AI technology would therefore be as a valuable adjunct in the mission towards improving sustainability in ophthalmology.