Table 1 Themes of factors operating as barriers

 Scepticism/attitudes

Clinicians held a negative attitude towards the OVT modality [17, 19, 22, 23, 25]

 Lack of training/experience

Clinicians lack training and experience using OVT [19, 22]

 Lack of need for OVT

Clinicians were unaware of the need for OVT [22]

 Lack of time

Clinicians did not have time to familiarise themselves with the OVT modality [22]

 Scheduling

Services experienced difficulties incorporating OVT sessions into existing schedules [18, 19, 22]

 Staffing

Services did not have enough staff to dedicate to OVT implementation [17,18,19, 22]

 Logistical support

Services lacked the logistical support required to implement OVT [22]

 Connection

Services lacked the necessary internet infrastructure to implement OVT [19, 22, 24, 36, 37]

 Set up

Services lacked the expertise to install the OVT software and hardware [17, 19, 22]

 Technical support

Services lacked the necessary technical support to oversee implementation [17, 22]

 Space

Services lacked the required space to set up dedicated OVT rooms [18, 24]

 Equipment

Services lacked the required equipment (e.g., headphones and webcams) [18, 24]

 Funding

Services lacked the funding required to implement and sustain the OVT service [19]

 Bureaucratic delays

OVT implementation was delayed due to administrative and ethical issues between collaborators [19, 25]

 Communication

OVT implementation was delayed due to communication issues between collaborators [19]

 Modifying existing policy

Services needed to modify existing policy to implement OVT [19]

 Recruitment

Services and researchers struggled to recruit clients to participate in OVT trials [17, 19, 22]