Solutions of cysteine, sodium edetic acid, and calcium edetic acid were topically applied to alkali-burned corneas of rabbits. Cysteine proved to be the most effective in preventing ulcers in 13 of 16 eyes. Sodium edetic acid was less effective and calcium edetic acid not at all.
Brown SI, Weller CA. Collagenase Inhibitors in Prevention of Ulcers of Alkali-Burned Cornea. Arch Ophthalmol. 1970;83(3):352-353. doi:10.1001/archopht.1970.00990030352013