While, in pathological conditions, such as glaucoma, the increased IOP will alter the level of NGF and NGF receptor expression, glaucoma significantly reduces the content of NGF in the cerebrospinal fluid (CSF) and lateral geniculate nucleus (LGN), but serum NGF protein levels may not be affected; this finding suggests that the NGF present in the CSF is most likely taken up by damaged retinal or brain neurons. This evidence concerns the gene NGFR and glaucoma.