Maybe some others may benefit from my experiences, so -
I've always had 'dry eyes' and opticians usually recommend drinking plenty of fluids, while I often buy drops for tired eyes.
However a few months ago I awoke one morning to find my left eye quite gummed close. I gently prised it open but felt a bit of discomfort and had blurry vision, which I assumed would resolve itself over a day or two. It didn't and I made an appointment with my optician (Peter - a keen WW2 Tamiya modeller!). He examined my eyes and sent off scans to Ninewells teaching hospital a few miles away in Dundee.
Peter came back to me to say I had a condition called map dot fingerprint dystrophy, which basically means I had pulled the top epithelial layer of my eyeball away from the lower layers resulting in a crease. It's evidently quite common on the sclera (white bit) but my crease ran across the iris, thus affecting my ability to focus.
A few weeks later and I am lying on my back in Ninewells with a consultant pouring anaesthetic then alcohol into my eye to loosen and dissolve the epithelium and wipe away the offending crease. I thanked him profusely, but he said 'you will not be thanking me when the anaesthetic wears off!' Sure enough, a couple of days of hell ensued until it started to heal and I'm now starting to get my vision sharpening up again.
You don't realise how much you rely on binocular vision until you try to wield a paint brush on a model and you cannot judge how far the tip is from the surface. The last few stages of the Little Blue Fokker took ten times as long as usual!
Thankfully I'm back to stereo now.
Anyway, I'm not really one to talk about aches and pains etc online, but I mention this here in case others have dry gritty eyes. I will regularly apply eye drops now but will always keep some on the bedside table to use when I wake up. I'd recommend everybody to do the same and if you wake with a gummed-up eye, for goodness sake don't peel it open without applying some drops or even water first of all!
Sandy