Travel-associated emissions of intravitreal injections

Intravitreal injections (IVIs) are among the most frequently performed ophthalmic procedures and have been associated with a substantial carbon footprint. Travel-associated emissions are considered a key driver of IVIs' carbon footprint; however, no study in a country with a decentralised healthcare system has assessed IVI-related emissions. Here, the IVI-associated carbon footprint in an urban German tertiary referral centre was investigated.

In total, 340 patients were included. The carbon footprint was assessed based on the distance travelled by patients and accompanying persons, the mode of transport, and postoperative follow-up visits. Demographic data, treatment indication, and the injected medication were collected.

The average travel-associated CO₂ equivalent (CO₂eq) for a single IVI was 11.1 kg. Of this, 9.1 kg CO₂eq and 2 kg CO₂eq were due to travel to the injection clinic and to follow-up visits, respectively. Anti-VEGF treatment for common diseases such as age-related macular degeneration and diabetic macular edema was associated with a lower CO₂eq compared with treatment of patients suffering from less prevalent conditions such as uveitis (10.8 kg vs. 15.6 kg). The majority of patients (49%) travelled by public transport (median distance: 22.4 km); patients travelling by car (33%) usually covered longer distances (median distance: 61.5 km).

Travel is a meaningful contributor to the carbon footprint of IVIs. Mitigation may be achieved by various approaches, such as longer-acting therapeutic agents or bilateral injections. To implement strategies for more sustainable IVIs, ophthalmologists may be encouraged by local and national bodies to incorporate environmental criteria into their practice.