Impact of the United Kingdom (UK) COVID-19 lockdown measures on air pollution and ocular surface disease symptomatology amongst shielding patients

Purpose : Worldwide lockdown reduced global air pollution during the SARS-CoV-2 pandemic. In this study, we evaluate whether the UK lockdown impacted upon dry eye symptoms in severe ocular surface disease (OSD) patients and whether there is a relationship with changes in air pollution levels. Methods : 35 OSD patients (median age 70 (range 42-85) years;17(48.5%) females;22(63%) ocular mucous membrane pemphigoid;3(9%) high-risk corneal transplant recipients;4(12%) ulcerative keratitis;2(6%) Stevens-Johnson syndrome;3(9%) other (granulomatous polyangiitis, Sjogren's syndrome, pemphigus vulgaris) maintained on systemic immunosuppression including mycophenolate mofetil, azathioprine, tacrolimus, methotrexate and cyclophosphamide achieved a risk stratification score of >3, defined as coronavirus high-risk and fulfilled the government criteria for shielding for a minimum of 12 weeks. Symptoms and air pollutions data were considered from three different time periods categorised as pre, during and post-lockdown. Pre-lockdown symptoms were curated from hospital electronic databases using the OSDI symptom questionnaire (Allergan plc, Irvine, CA) whilst during and post-lockdown data were obtained via postal hardcopy. Air pollution data for patient postcodes were derived from Department for Environment, Food, & Rural Affairs (DEFRA) and from the Automatic Urban and Rural Network (AURN) monitoring network for nitrogen dioxides (NO ), nitrogen oxides (NOx) particulate matter 10μm (PM ) and 2.5μm (PM ). Results : A 12% increase in symptom scores were observed during versus pre periods (36.11±16.09 vs 32.24±29.17, p=0.381). Similarly, a 19% reduction was observed between the during and post periods (36.11±16.09 vs 29.46 ± 26.29, p=0.144). However, significant reduction of NO (35%, from 17.11±6.87 to 11.17±4.79, p<0.001) and NOx (44%, from 26.06±11.64 to 14.53±7.18, p<0.001) respectively, were observed between pre and during periods. Symptoms and air pollutants were not correlated across all the considered periods. Conclusions : Despite the reduction of air pollutants due to lockdown measures, dry eye symptoms experienced by immunosuppressed OSD patients were increased. This might be due to a range of environmental factors such as increase use of electronic blue screen electronic devices as well as the psychological impact of lockdown on patient wellbeing.