If for some reason you cannot have eye drops ( allergic reactions in the past) then please do tell them. I came clean about the whole of my medical history, I had to. And I was offered screening without eye drops.
Please don't say, you have to have eye drops, I couldn't because I already have severe photophobia, and the only eye drops I can tolerate is tears naturale for dry eyes.
Mine came back clear. It really is nothing to worry about and takes about 20 - 30 minutes.