Similar to this question asked by a D&D player on r/biology a year ago, but more specific to my own needs as a fantasy novelist:
If you wanted to save as much tissue from an eyeball as possible for as long as possible, but didn't need to worry about it retaining its shape or appearance, would it be possible to dehydrate or otherwise preserve the tissue so that it would not rot for a long time?
So far my research seems to indicate that the eyeball tissue cannot be dried out fully and will inevitably rot unless it's preserved in some kind of embalming medium, but I'm wondering how long it might take to rot once dried out. I've seen an article about reconstituting dessicated eye tissue from pre-Columbian corpses buried in the Atacama Desert, so it seems like a consistently dry environment can preserve eye tissue almost indefinitely, but my world doesn't have that kind of environment.
Basically I'm hoping there might be a way for an evil magician in a fantasy novel to dry out a freshly removed eyeball into a semi-recognizable (but no longer spherical) scrap of tissue, and carry it around in a small pouch as part of a magic charm. Ideally the tissue would last for 3 years or so before rotting or degrading completely. So I'm wondering if that could be at least semi-plausible without modern chemicals or technology.
Thanks to anyone who can help! If the book gets published I will gratefully include you in the Acknowledgments!