Cataract surgery and environmental sustainability: a comparative analysis of single-use versus reusable cassettes in phacoemulsification

Introduction

The environmental impacts of our daily activities have received significant attention in recent years, prompting a re-evaluation of approaches across various sectors. Many of us recognise the primary sources of greenhouse gas emissions in our daily lives and industries, but the contribution of the healthcare sector to global emissions is often overlooked, indicating a need for increased awareness and consideration. Globally, the healthcare sector contributes approximately 5% of all greenhouse gas emissions, with percentages varying between 4% and 10% among countries. These statistics should raise concerns and motivate physicians to explore more sustainable practices within the healthcare sector.1

In the field of ophthalmology, cataract removal stands out as the most frequently performed surgical procedure, known for its significant carbon footprint. The conventional method of cataract surgery, phacoemulsification, results in the release of a significant amount of carbon dioxide (CO₂) and generates considerable waste. Morris et al published carbon footprint data for a single cataract operation in the UK in 2013, estimating it at 181.8 CO₂eq.2 Subsequently, numerous other studies worldwide have examined the environmental impact of cataract surgery.3–6

The environmental impact of these surgeries stems from factors such as material procurement, patient and staff transportation, energy consumption and waste disposal. The necessity for more sustainable approaches in ophthalmology, including cataract surgery, is evident. In developing nations, alternative techniques such as manual small incision cataract surgery (MSICS) have emerged. These methods offer comparable safety and efficacy to phacoemulsification but come with significant environmental advantages.

In India, the Aravind Eye Care System (AECS) has implemented a high-volume approach, performing up to 1000 cataract extraction surgeries each working day, leading to a significant reduction in energy consumption per surgery.7 The system also prioritises sterilisation and the reuse of materials, resulting in 6 kg CO₂eq emissions per procedure, compared with 180 kg CO₂eq emissions in the UK. Despite the established effectiveness and environmental advantages of sustainable practices such as those implemented at AECS, the widespread adoption and proficiency of such techniques remain limited. Obstacles to the implementation of these sustainable practices include regulatory frameworks, infection control guidelines, and the varying socioeconomic conditions and expectations prevalent in more developed nations.8

Given these considerations, our study aims to contrast the sustainability aspects and cost-savings of surgeries conducted via phacoemulsification, distinguishing between those using single-use and reusable cassettes. The adoption of sustainable practices holds the potential to not only reduce the carbon footprint and waste generation but also deliver significant cost-savings. As the healthcare industry increasingly prioritises sustainable solutions, we can collectively strive for a future that is more environmentally aware and economically sustainable. This collaborative effort aims to simultaneously reduce our environmental footprint while upholding high-quality patient care.

Materials and methods

Results

For the single-use phacoemulsification machine, each pack required for one cataract surgery was fully encased in plastic. These packs included one cassette for the machine, tubings and plastic covering for the phacoemulsification machine’s screen, totalling a weight of 407 g (Fusion dual pump pack disposable OP071 Whitestar Signature). For 10 cataract surgeries, the total plastic weight amounted to 4070 g or 4.07 kg, and for 1000 cataract surgeries, it reached 407 kg (figure 1).

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The packaging provided by the company consists of a box containing 12 packs for 12 cataract surgeries, with a storage volume of 44.18 dm³ (2×4.7×4.7 dm) for one pack. For 1000 cataract surgeries, this amounts to 3682 dm³ (44.18x12×1000) or 3.682 cubic m³ (figure 2).

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For the daily reusable cassette system, we calculated the usage of one cassette for each day’s schedule of operations, with the tubings being changed for each individual procedure. As a standard daily surgical programme consists of 10 cataract surgeries, we computed the weight of one cassette (cassette peristaltic Sophi Eco) with all its plastic components (including the pouch, tubings for a single procedure and plastic covering for the screen), totalling 238 g. The weight of nine tubing sets for the following nine procedures was 85 g. For 10 cataract surgeries, the total weight reached 1003 g or 1.003 kg (comprising one cassette with all components and nine tubing sets). For 1000 cataract surgeries, this amounted to 100.3 kg (figure 1).

The carton box size for 16 cassettes measures 30.25 dm³ (4.36×2.99×2.32 dm), while the carton box size for 10 tubings measures 11.10 dm³ (2.04×2.82×1.93 dm). For 1000 cataract surgeries, we will require 100 daily cassettes (for 10 cataract surgeries each), resulting in 100 cassettes and 900 tubings. This totals 189 dm³ for the cassettes and 999 dm³ for the tubings, summing up to 1188 dm³ or 1188 m³ (figure 2).

The disparity in plastic usage between the two machines is striking. The Sophi machine achieves a reduction of approximately 75.3% in plastic weight compared with the Whitestar Signature machine. Similarly, there is a 67.7% reduction in storage volume achieved by the daily reusable cassette phacomachine.

For the cost-savings, we calculated the expenses for 10 procedures for each device. The device with a single-use cassette requires the purchase of 10 cassettes and 10 bottles, totalling €320. Conversely, the device with the daily reusable cassette necessitates the purchase of a day cassette containing the first tubing, priced at €43.19, nine tubings for subsequent procedures, costing €201.60, and five bottles, priced at €21.05. The total cost for 10 procedures is €265.84 (43.19+201.60+21.05). Therefore, the device with reusable cassettes provides cost-savings of €54.16 (16.92%) per 10 procedures.

Regarding surgical efficiency, an external observer analysed the course of surgical activity during 10 procedures. With a single-use cassette machine, the surgeon must wait for the nurse to insert the cassette. Conversely, for the reusable cassette phacoemulsification machine, the surgeon does not need to wait for the operating nurse and can independently change the tubing and immediately commence the calibration of the reusable cassette phacoemulsification machine.

The external observer also measured the calibration time during 10 procedures(the prime/tune process fills the irrigation/aspiration tubing with fluid, performs a vacuum check, and tests and characterises the phaco handpiece) for each machine. The daily reusable cassette phacomachine Sophi has a mean priming time of 397.93 s, whereas the single-use cassette phacomachine has a mean priming time of 820 s. This translates to a gain of 422.07 s (~7 min) per 10 cataract surgeries (figure 3) for the Sophi machine versus the single-use cassette machine.

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Discussion

This study demonstrates that using a phacomachine with reusable cassettes (vs single-use) leads to a remarkable reduction (75.3% by weight) in plastic waste. Furthermore, the 67.7% decrease in storage volume substantially cuts down on storage and transportation requirements and associated costs. These findings highlight the substantial environmental benefits associated with the utilisation of the phacoemulsification machine equipped with daily reusable cassettes versus the conventional single-use cassette phacoemulsification machine. The notable reductions in both plastic consumption and storage volume percentage align with sustainability efforts, effectively mitigating resource depletion, waste generation and storage demands. As both systems maintain patient safety and strict adherence to sterilisation protocols, surgeons can confidently opt for either system, assured that patient well-being remains uncompromised.

The need for sustainable healthcare practices, including cataract surgery, becomes evident when considering the significant contribution to global greenhouse gas emissions by the healthcare sector. Traditional phacoemulsification surgery, the most frequently performed procedure in ophthalmology, is well documented for its considerable environmental impact. Nevertheless, alternative techniques like MSICS and innovative technologies such as daily reusable phacomachine cassettes hold promise as solutions for alleviating the carbon footprint and waste generation associated with cataract surgeries.

Beyond their favourable environmental impact, daily reusable cassettes also present an economic advantage, with cost-savings for 10 procedures of €54.16 or 16.9%, over single-use cassettes. This direct financial saving is in addition to the reduced cost associated with managing less stock. These savings provide opportunities to reallocate resources to further enhance patient care, expand services or invest in other sustainable initiatives.

When comparing the benefits of a machine with single-use cassettes and a machine with daily reusable cassettes, it is essential to consider the possibility of complications such as endophthalmitis. Patient well-being and positive outcomes are paramount considerations in any surgical procedure. The phacomachine with daily reusable cassettes is built to prevent contamination: the aspiration path and irrigation path are completely separated; the pressure measurements are contactless to the device; a foil between the patient fluid and the device completely prevents contamination of the hospital air; the plugs are coded to prevent incorrect insertion; and the automatic cassette feeder prevents contamination between the device and the assistant’s gloves. At our tertiary eye care centre where this study was conducted, no endophthalmitis was encountered during cataract procedures in the 2 years following the availability of both phacomachines. Surgeons can confidently rely on the established safety standards and efficacy of the phacomachines to ensure optimal surgical outcomes for their patients.

Also, when comparing different cassette systems, surgical efficiency emerges as another crucial consideration. The efficiency of a phacoemulsification machine can significantly influence various aspects of surgery, including workflow, operating room utilisation and overall surgical outcomes. Streamlined surgical processes, characterised by reduced downtime between cases (as a consequence of shorter priming time), are evident with the daily reusable cassette system. Such efficiency enhancements contribute to optimised resource (eg, operating room) utilisation and decreased energy consumption during surgeries, thus reducing the overall carbon footprint of the hospital. These outcomes align with the healthcare sector’s growing commitment to environmental sustainability.

Although informative, our study has several limitations. As a single-centre study, the findings may have limited applicability to other healthcare settings. Furthermore, the study primarily focused on waste generation and did not consider other environmental aspects, such as greenhouse gas emissions or energy consumption. Also, the cost analysis only considered specific direct costs, while indirect costs such as labour and equipment maintenance were not included. Moreover, it is important to acknowledge that certain factors, such as surgical techniques, surgeon experience and patient characteristics among different operating rooms, could affect resource utilisation differently. Lastly, there are very little data on this topic from the literature to contrast our findings and therefore, we call for additional studies to further validate and expand upon these conclusions.

Despite these limitations, our study’s findings provide valuable insights into the potential environmental and cost implications of employing different cassette systems in phacoemulsification surgeries. They have the potential to influence the manufacturing industry as well as the purchasing decisions of prospective users.

Conclusion

This study demonstrates that phacomachines equipped with reusable cassettes outperform their single-use cassette counterparts in terms of environmental impact, cost and surgical efficiency. These findings provide valuable guidance to healthcare professionals and encourage the adoption of innovative technologies. This shift to reusable cassette machines enables healthcare institutions to maximise their financial and physical resources while mitigating the adverse effects of healthcare activities on the environment.