Is the field vision test part of the retinopathy screening done by the NHS...or is this something done by an optician instead....I am a little confused ....

...what happens if someone has their retinopathy screening done but refuses to go and have their eyes tested by an optician....does this miss out on some of the tests required....would this make their ability to drive invalidated....
.....is a field vision test a compulsory requirement for diabetics (T2 on insulin) when informing DVLA about their diabetes and renewing their licence...how will the DVLA know if they have had it done or not....