My ds has regular eye injections and various related treatments and last month, when at the eye hospital, a member of staff challenged a family who were waiting.
Only the father spoke English, the mother's clothing was clearly suited to a hot climate (suggesting she had only just arrived here), there was a grandmother and a couple of children too.
The staff member produced forms and told the father that he must either complete the paperwork to show that the family weren't illegal immigrants, or pay, upfront, for the treatment h is wife wanted. This included several eye tests and injections which amounted to thousands of pounds.
The family refused to complete the forms and subsequently left the hospital.
My son gets this wonderful eye treatment on the NH every month.