2.1 Cross-sectional Questionnaire
The most common methodology for assessment in the articles searched was
a cross-sectional questionnaire which were conducted over a variety of
mediums i.e. face to face, mobile application or web-based forms. The
cohort of patients targeted also varied between inpatient and outpatient
populations and in their geographical location (Tables 2 and 3). Whilst
there are clear limitations to this approach and it is not possible to
demonstrate a direct causal relationship between COVID-19 and OD but
they are able to present associations in the symptomology of this
pandemic.