Parapapillary atrophy in optic neuropathies: Histology and clinical relevance.

Parapapillary atrophy is one of the parameters of the optic nerve head area which are assessed during the ophthalmoscopic examination particularly useful to characterize glaucomatous optic neuropathy. Optical coherence tomography evaluation provides high-resolution images of the optic nerve head and surrounding area, and can be used to study parapapillary atrophy. Different parapapillary atrophy zones were described depending on their histological features and research has been conducted to investigate the possible association between the presence and/ or size of parapapillary atrophy zones and several optic nerve disorders. In this review we discuss the histology and the clinical findings related to parapapillary atrophy in patients with glaucomatous optic neuropathy, non-glaucomatous optic neuropathies (e.g. arteritic and non-arteritic anterior ischemic optic neuropathies; suprasellar and parasellar tumors), and other ocular conditions (e.g. high myopia; age-related macular degeneration). Two different histologic classifications were identified. Parapapillary atrophy was demonstrated in glaucoma and glaucoma-like neuropathies, but not in other types of optic nerve disorders.