Environmental Impact Of Glaucoma Patients Undergoing Visual Field

Glaucoma is a chronic condition that requires lifelong management and frequent follow-up, especially in an ageing population. This makes considerations around sustainability increasingly important. Measuring the environmental impact of the entire course of glaucoma care can be challenging due to the variation in patient care pathways. However, it is possible to estimate the environmental impact of specific aspects of care, such as visual field (VF) testing. In this study, we aimed to approximate the carbon emissions attributable to VF testing and to compare traditional VF devices like the Humphrey Visual Field (HVF) with newer technologies, Online Circular Contrast Perimetry (OCCP), which can be used from home on a personal computer. 

University hospital

Based on previous estimates of ophthalmology-related emissions, we considered sources of carbon emissions including patient and staff transport and energy consumption of VF devices. We recorded patient travel methods and distances for VF tests to the Hospital and estimated emissions based on the average emissions per kilometer for cars. The emissions attributed to the use of the HVF system were estimated based on the cost of the device, to account for the embedded carbon in manufacturing and supply, and the expected lifespan of 20,000 tests. For comparison, the OCCP platform, which allows VF testing from home using a personal computer, was evaluated for its energy consumption.

The study revealed that patient transportation was the largest contributor to carbon emissions in glaucoma care. Patients traveled an average distance of 51.3 km to Dunedin Hospital, resulting in an average of 12.2 kg of CO2 emissions per trip. The emissions associated with the use of the HVF system were estimated at 1.71 kg of CO2 per test, based on the device's cost and lifespan, with a total of 15.64 kg of CO2 emissions per VF test. The contribution of disposable materials and energy consumption was relatively small but measurable. In contrast, OCCP home-based testing significantly reduced emissions, with energy consumption from personal computers contributing just 0.01 kg CO2 per test for desktop computers and 0.004 kg CO2 for laptops.

Transportation is the major contributor to the carbon footprint of glaucoma care, particularly in VF testing. Home-based VF solutions like OCCP have the potential to drastically reduce emissions by eliminating the need for patient travel and minimizing device-related emissions. However, it is important to note that while the energy consumption of personal computers used for OCCP testing is minimal, the embedded carbon footprint of these computers and the OCCP platform itself remains unclear and warrants further investigation. An additional advantage of home-based VF testing is the potential to increase the frequency of testing, which could improve clinical safety by better detecting glaucoma progression.