Sorry to hear about Rascal, Sabrina
We had a retriever who had an inherited eye condition. He was blind from an early age.All I can say is that he was a wonderfully happy dog and led a very active life until the age of 14(old for a Flat Coated Retriever). Tell your OH to try not to worry. We made sure we used lots of verbal commands/ reassurance and of course looked out for dangerous situations that he would be unaware of eg. things he could run head first into, drops, caution when meeting other dogs. Also kept furniture in the same place, didn't leave vacuum in unfamiliar place, etc. He was a very friendly, outgoing boy but always said his name if strangers were about to touch him so that he was never shocked by the sudden touch.
My children grew up with him and he went everywhere with us .... holidays, the park, town and so on. You get used to thinking of the little things that make life easier/safer for them and it becomes second nature.
Hope that eases any concerns your OH may have