I have eye drops on prescription from the ophthalmologist and I drink 2-3 litres of fluid a day on advice of my nephrologist for my PKD which he assures me is not causing any of my symptoms.

My podiatrist has told me about another test for SFN which looks at your eye and is none invasive I can't remember what it's called I will check later

I think I am going to have to look at a second opinion but being in the UK the refferal a are just done to a hospital team so no idea who you will see and I don't want to have a wasted refferal as once you have had two it's pretty hard to get another