As well as providing eye tests, some opticians (also called optometrists) some also provide urgent or minor eye care services. They have specialist equipment meaning that they may be able to treat your condition.
If you speak with your normal optician first they will be able to advise if they can provide the help that you need. If not, providers of urgent and minor eye services can be found here. 111 may also be able to direct you to the appropriate local service, especially out of hours. You can call 111 or get help from 111 online.
NHS Eye Tests
View this NHS page about NHS eye tests and finding one near to you.