Glaucoma and neuroprotection: C-Type Natriuretic Peptide and opioid receptors

I have been coming across a few articles and studies dealing with c-type natriuretic peptides (CNP) and opioid receptors as they potentially  relate to glaucoma, IOP and neuroprotection. While I don't have enough to go on in order to build any cogent arguments, I will present what I have found as a matter of interest. As a quick preview, it seems that CNP has neuroprotective effects..