It causes no harm at all because the eyecup is first filled with distilled water so its diluted and your only talking about drops.  My eyecup holds 2 teaspoons of water and in that you're only putting drops of the tincture.  I'm up to 4 drops now.  Dr. Schulze says to put 10 drops YIKES!

We had one lady who didn't read the label and put the drops straight into her eye, not in an eyecup filled with water and yeah, it hurt like hell she said lol.  She said her husband had first done that and was acting like a baby so she grabbed the dropper and put drops straight in her eye too and started screaming.  Once they got over the EXTREME BURN they were fine, no harm done to the eyes.  Of course I wouldn't be putting straight alcohol in my eyes lol.  

If fact you wouldn't believe just how soothed your eyes feel after you wash with the tincture.  It makes things brighter, cleaner, sharper somehow and so very soothing.  It truly is amazing.