Molecular imaging reveals unique degenerative changes in experimental glaucoma.

Experimentally induced changes in the central visual pathway were studied by using positron emission tomography in monkeys with unilateral hypertension glaucoma. In 2-[18F]fluoro-2-deoxy-glucose studies, monocular visual stimulation of the affected eye yielded significantly reduced neural responses in the occipital visuocortical areas. The response reduction was limited to the visual cortex ipsilateral to the affected eye, indicating the unique vulnerability of ipsilateral visual cortex in experimental unilateral glaucoma. In addition, in [ 11 C]PK11195 positron emission tomography and immunohistochemical studies, selective accumulation of activated microglia, a sign of neural degeneration, was found bilaterally in lateral geniculate nuclei. The present findings establish the usefulness of noninvasive molecular imaging for early diagnosis of glaucoma by providing a sharper surrogate end point for an early phase of glaucoma.