An NHS hospital emits 20x more carbon per cataract surgery than this Indian hospital. Here's why.

A phacoemulsification and intraocular lens insertion cataract operation at India's Aravind Eye Hospital produces roughly 5% of the carbon of the same operation in the UK. [1, 2] At Aravind's hospital in Pondicherry, innovative measures allow its daily operations to create minimal amounts of emissions, inside and out of theatre, with comparable outcomes. As cataract surgery is the most common surgical procedure in the UK, with almost half a million operations a year, [3] lessons must be learnt from other healthcare systems to reduce the emissions it creates and make inroads on the NHS's 2040 net-zero target. [4]

Reaching sustainability goals and improving clinical outcomes are often thought to be two independent targets, however, climate change is not solely an environmental problem; it is also a health problem. Climate change is linked to many adverse health outcomes, ranging from chronic illness to nutritional deficiency to increased rates of suicide. [5]

The impact of climate change on ocular disease is also evident. [6] Global warming could result in more frequent retinal detachment and uveitis cases, while also changing microbial patterns in infectious eye disease. [6] Ultraviolet radiation exposure may increase the incidence of cataracts and age-related macular degeneration. [6] Air pollution has been associated with allergic conjunctivitis, narrower retinal arteries and a higher risk of glaucoma. [6]

Ophthalmology in the UK is world-leading: UK researchers coined, and now lead, the field of "oculomics". [7] This leaves no reason for stagnation on the sustainability front, where the specialty can also be best-in-class and lead by example, as evidenced by the Aravind Eye Hospital. [1] As healthcare generates around 4.5% of the world's greenhouse gas emissions, [8] differences made at an individual, hospital and organisational level would all be of value.

24% of the NHS's total emissions are generated from the direct delivery of care. [9] Individually, we can cut down on our quota through simple measures, such as limiting the use of non-sterile gloves to bodily fluid and chemical exposure and recycling paper towels.

Additionally, we can take notes from Aravind, who reuse surgical PPE to reduce production-related emissions. [1] Though most UK theatres use single-use gowns, scrub hats can be multi-use, or individually owned, rather than single-use, saving each theatre practitioner hundreds of disposable caps a year.

Singular actions can also make a difference through sustainable prescribing. The most common example relates to inhalers, where dry powder inhalers have around a tenth of the carbon footprint of metered-dose inhalers. [10]

A less well-known example is eye drops: preservative-free lubricating drops can now be prescribed in multidose bottles designed to limit contamination, which use about eight times less plastic and nine times less transport energy than single-dose vials. [11] Aravind takes this further, sharing multiuse pharmaceuticals across patients in theatre, [1] in contrast to the UK where, in my experience, two plastic vials are discarded per patient in the pre-operative room alone.

Waste generation in hospital significantly contributes to poor sustainability. How many times have you seen a half-used single-use pack of equipment left on a counter? Or tried to find equipment, only to find it in a procedure pack, which is opened just to access the item and discard the rest.

These packs can be incredibly useful for efficiency and to prevent waste, but only when used appropriately. By gaining feedback from staff, auditing and referring to policy, trusts can optimise these packs to ensure the minimum generation of single-use plastic waste.

In Aravind, two thirds of the waste generated in theatre is recycled, [1] yet in the UK, almost all surgical waste appears to go into the same bin.

In fact, it is often the case that many of the unpackaged metal surgical instruments go unused but are disposed of at the end of the procedure. While some unused equipment may be on standby for emergency situations, much is due to variable surgical techniques, necessitating different tools. Policy-abiding solutions include pioneering custom surgeon equipment sets, liaising with scrub nurses regarding usage and bilateral cataract surgery, an increasingly popular option with high patient satisfaction that cuts the number of hospital visits. [12]

At Aravind, instruments are flash autoclaved and reused between cases, with thorough sterilisation at the end of the day, while surgical gloves are cleaned with antiseptic gel between cases and discarded after about ten. [1] UK infection-control rules forbid this, yet Aravind's complication rates meet developed-world standards, with endophthalmitis in 0.03% of cases. [1]

The secret to Aravind's success appears to be its efficiency. Every surgical staff member knows their role, culminating in an average of nine minutes from the patient entering theatre to leaving it, and 750 to 1,500 operations a day across Aravind. [1]

Surgeons are solely responsible for the surgery, with two adjacent tables present in one room, minimising energy use and maximising utilisation of scrub nurses. [1] Housekeeping staff manage waste disposal routes, and local sterilisation department staff hand-wash, ultrasonically clean and then autoclave instruments. [1] A cohesive team and localised sterility unit reduce the average energy consumption per patient, and short autoclave cycles mean fewer instruments need to be bought. [1]

The NHS can follow suit, but many of these surgical strategies require policy change before being applicable to the UK. Therefore, review and comparison of outcomes is key to spark progressive changes in policy, ensuring a sustainable future.

Hospital design, though, including local sterile departments, is within the NHS's reach. The Aravind Eye Hospital also harvests rainwater, treats its own waste water on site, draws much of its power from rooftop solar and has multiple satellite centres to reduce patient travel. [1, 14]

More satellite hubs for appointments such as intravitreal injections or eye screening would reduce travel-related emissions: in one Irish service, patient travel made up 77% of an injection's carbon footprint, excluding the drug. [13] More appointment sites may also increase compliance by saving patient time. The same can be achieved by telephone follow-up appointments, eliminating related emissions entirely.

Multiple routes to improving environmental sustainability in the NHS are available, but some are also yet to be discovered. An evidence-base is needed for policy change, therefore the funding of research grants into environmental sustainability is essential to incentivise academics to explore sustainable practice options and innovations. These relatively small investments can create large environmental and cost-saving impact.

The impact of climate change in everyday life is clear, with continual record-breaking temperatures and adverse weather events across the globe. In parallel, it is having a detrimental impact on global patient health.

All healthcare professionals have a significant role and responsibility to cut healthcare's emissions, both individually and organisationally. This could be through being mindful of the plastic waste we generate, to owning a scrub hat, to lobbying for policy change towards reusables in theatre and funding of research to explore proposed interventions. The eye community has the potential to lead by example, with multiple practised avenues available to pioneer sustainability in the NHS.

References

1. Thiel CL, Schehlein E, Ravilla T, Ravindran RD, Robin AL, Saeedi OJ, et al. Cataract surgery and environmental sustainability: Waste and lifecycle assessment of phacoemulsification at a private healthcare facility. J Cataract Refract Surg. 2017;43(11):1391-8. https://doi.org/10.1016/j.jcrs.2017.08.017

2. Morris DS, Wright T, Somner JEA, Connor A. The carbon footprint of cataract surgery. Eye (Lond). 2013;27(4):495-501. https://doi.org/10.1038/eye.2013.9

3. The Royal College of Ophthalmologists. National Ophthalmology Database Audit: sixth prospective annual cataract report. 2023. Accessed 29 October 2026. Available at: https://www.rcophth.ac.uk/?p=13124

4. NHS England. Delivering a net zero NHS. Accessed 30 August 2026. Available at: https://www.england.nhs.uk/greenernhs/a-net-zero-nhs/

5. Rocque RJ, Beaudoin C, Ndjaboue R, Cameron L, Poirier-Bergeron L, Poulin-Rheault RA, et al. Health effects of climate change: an overview of systematic reviews. BMJ Open. 2021;11(6):e046333. https://doi.org/10.1136/bmjopen-2020-046333

6. Malik A. Looking Ahead – How will the climate crisis impact eyecare? The British Student Doctor Journal. 2025:17. https://doi.org/10.18573/bsdj.412

7. Wagner SK, Fu DJ, Faes L, Liu X, et al. Insights into systemic disease through retinal imaging-based oculomics. Transl Vis Sci Technol. 2020;9(2):6. https://doi.org/10.1167/tvst.9.2.6

8. Downey GP. Medical industry contributions to the climate crisis: Behind the green drapes. Can J Respir Crit Care Sleep Med. 2023;7(5):228-31. https://doi.org/10.1080/24745332.2023.2268075

9. Tennison I, Roschnik S, Ashby B, Boyd R, Hamilton I, Oreszczyn T et al. Health care's response to climate change: a carbon footprint assessment of the NHS in England. Lancet Planet Health. 2021;5(2):e84-e92. https://doi.org/10.1016/S2542-5196(20)30271-0

10. Panigone S, Sandri F, Ferri R, Volpato A, Nudo E, Nicolini G. Environmental impact of inhalers for respiratory diseases: decreasing the carbon footprint while preserving patient-tailored treatment. BMJ Open Respir Res. 2020;7(1):e000571. https://doi.org/10.1136/bmjresp-2020-000571

11. Latham SG, Williams RL, Grover LM, Rauz S. Achieving net-zero in the dry eye disease care pathway. Eye (Lond). 2024;38(5):829-40. https://doi.org/10.1038/s41433-023-02814-3

12. Obuchowska I, Micun Z, Młynarczyk M, Dmuchowska DA, Konopińska J. Pros and cons of immediate sequential bilateral cataract surgery from a patient perspective: a survey. Int J Environ Res Public Health. 2023;20(2):1611. https://doi.org/10.3390/ijerph20021611

13. Power B, Brady R, Connell P. Analyzing the carbon footprint of an intravitreal injection. J Ophthalmic Vis Res. 2021;16(3):367-76. https://doi.org/10.18502/jovr.v16i3.9433

14. Venkatesh R, Shukla AG. Sustainability in eyecare: Aravind Eye Hospital's low carbon eyecare system. Eye News. 2021;28(2). https://www.eyenews.uk.com/features/ophthalmology/post/sustainability-in-eyecare-aravind-eye-hospital-s-low-carbon-eyecare-system