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Cataract surgery and environmental sustainability: a comparative analysis of single-use versus reusable cassettes in phacoemulsification
  1. Oscar Kallay1,
  2. Rayane Sadad2,
  3. Ahmed Zafzafi3,
  4. Elie Motulsky4
  1. 1Head of Department of Ophthalmology, Centre Médical de l'Alliance, Braine-l'Alleud, Belgium
  2. 2Department of Ophthalmology, Erasmus Hospital, Brussels, Belgium
  3. 3Department of Ophthalmology, Centre Médical de l'Alliance, Braine-l'Alleud, Belgium
  4. 4Head of Departement of Ophthalmology, Erasmus Hospital, Brussels, Belgium
  1. Correspondence to Dr Elie Motulsky; elie.motulsky{at}hubruxelles.be

Abstract

Objective To compare sustainability, financial implications and surgical efficiency of two phacoemulsification cassette systems for cataract surgery: a machine with single-use cassettes and another with daily, reusable ones.

Methods Observational study involving retrospective cataract surgery data collection at the Centre Médical de l’Alliance, Braine-l’Alleud, Belgium, a tertiary eye care centre. Information on cassette weight, quantities and transport volume was obtained from routine procedures and purchasing records. The costs for each machine were calculated by reviewing the invoices received from the accounting department.

Results We found significant differences across comparisons. The reusable cassette machine, when compared with the single-use machine, used 306.7 kg less plastic (75.3% reduction), required 2494 m3 less storage per 1000 surgeries (67.7% decrease) and cost €54.16 less per 10 procedures (16.9% reduction). The machine with daily reusable cassettes also exhibited a 7-minute priming time advantage for 10 procedures, reducing downtime between cases.

Conclusions Our findings underscore the benefits of adopting reusable cassette systems: reduced plastic consumption, storage volume and priming time, as well as enhanced efficiency and cost-savings. Healthcare professionals and institutions are encouraged to embrace environmentally conscious initiatives. The use of reusable cassette systems for cataract surgeries offers a pathway to sustainable practices.

  • treatment surgery
  • epidemiology
  • public health
  • lens and zonules
  • cataract

Data availability statement

All data relevant to the study are included in the article or uploaded as supplemental information.

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WHAT IS ALREADY KNOWN ON THIS TOPIC

  • Several studies in different countries have previously investigated the amount of plastic waste generated by phacoemulsification cataract surgery, and the carbon footprint of these procedures has been analysed. However, no study has proposed practical solutions to improve the situation.

WHAT THIS STUDY ADDS

  • Through this study, we show that using a phacomachine with daily cassettes improves the carbon footprint of each cataract surgery procedure. Additionally, the reusable cassette machine is more efficient and reduces the cost of the procedure and the storage volume.

HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

  • Our study offers a practical solution to improve the carbon footprint associated with cataract surgery by using phacoemulsification machines with day cassettes. The results could influence the manufacturing industry as well as the purchasing decisions of prospective users.

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

Study design and setting

We performed an observational study involving retrospective cataract surgery data collection at the Centre Médical de l’Alliance, Braine-l’Alleud, Belgium, a tertiary eye care centre performing 1500 cataract procedures annually and employing both types of machines. Aggregate data were analysed, and no individual patient information was included in the dataset.

Data collection

A material flow analysis was conducted, which entailed direct observation of the operating room procedures to gain insights into the use of various materials during phacoemulsification surgeries. Data were collected from routine phacoemulsification surgical procedures without occurrences of vitreous loss or other complications. Detailed lists of cassettes and types (eg, reusable cassettes (Sophi, This AG, Switzerland) vs single-use cassettes (Whitestar Signature, Johnson & Johnson Vision, Santa Ana, California, USA)) used in the surgeries, complete with their respective weights, quantities and transport volumes, were obtained from purchasing department of the tertiary care centre.

To gain further insights into material usage and management practices, interviews were conducted with mid-level ophthalmic personnel. The weight of each cassette used in phacoemulsification surgeries was directly measured to determine the precise amount of material used during the procedures. Additionally, the volume of each box containing the cassettes was measured to assess the total packaging volume associated with the use of cassettes in phacoemulsification surgeries. The differences in plastic weight and volume between the two cassette systems were expressed as percentages to facilitate the comparison of their respective environmental impacts. These percentage differences were computed as the ratio of the difference in weight or volume to the original value, multiplied by 100. Expressing the differences in weight and volume between the two cassette systems as percentages allowed a comprehensive assessment of the environmental impact of both systems in the context of phacoemulsification surgeries. This approach offered a straightforward means of evaluating the potential reductions in plastic consumption and packaging volume.

Cost-savings analysis

The costs were calculated for both machines by comparing the various invoices received from the accounting department. These invoices provided us with the prices of the cassettes for each machine, the tubings for the reusable phacomachine cassettes and the infusion bottles.

Patient and public involvement

Patients and the public were not involved in the design, conduct, reporting or dissemination plans of our research.

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).

Figure 1

Total plastic weight for 10 and 1000 cataracts, using a phacomachine with single-use versus daily reusable cassettes.

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).

Figure 2

Packaging volumes measured for phacomachines with single-use versus daily reusable cassettes for 1000 cataracts.

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.

Figure 3

Packaging volumes measured for phacomachines with single-use versus daily reusable cassettes for 1000 cataracts.

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.

Data availability statement

All data relevant to the study are included in the article or uploaded as supplemental information.

Ethics statements

Patient consent for publication

Ethics approval

This study was exempt from formal research ethics approval due to the absence of human subjects involved and the non-utilisation of human subjects' data.

Acknowledgments

We thank Professor Jean B Nachega, University of Pittsburgh, Pennsylvania, USA, for critical review and advice on this manuscript.

References

Footnotes

  • Contributors OK—conception and design, acquisition of data, analysis and interpretation of data, and drafting the manuscript. All authors (OK, RS, AZ, EM) reviewed the results, contributed to the writing and approved the final version of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.