From Egyptian Secrets of Albertus Magnus, Joseph H. Peterson edition:
When a Horse has a Skin growing over the Retina of the Eye.
Take of fresh butter a piece as large as a pigeon's egg and knead with saffron. Put it into the eye of the horse, bandage the eye, and in twenty-four hours the skin will have vanished.
Take one pound of fresh butter, which has not been watered, put it into a pan, heat it, bake twenty cakes of it, keep the lard for future use. A spoonful of the same put into a beverage for a drink, and to desist from drinking anything else, and used as long as is desired, will cure. Probatum.
The grimoire Egyptian Secrets of Albertus Magnus lists this spell.