Diagnosis and clinical features of common optic neuropathies.

Disorders of the optic nerves (optic neuropathies) are some of the most common causes of visual loss, and can present in isolation or with associated neurological or systemic symptoms and signs. Several optic neuropathies-especially inflammatory optic neuropathies-are associated with neurological disorders and thus are often diagnosed and treated by neurologists. The mechanisms underlying optic neuropathies are diverse and typically manifest with decreased visual acuity, altered colour vision, and abnormal visual field in the affected eye. Diagnosis is made on the basis of clinical history and clinical examination, of which several aspects are particularly important, including the mode of onset of visual loss, the presence of pain with eye movements, the visual acuity, and the retention of colour vision. Advances in optic nerve imaging-particularly retinal digital photography, optical coherence tomography, and MRI techniques-have revolutionised the diagnosis and follow-up of patients with an optic neuropathy. Furthermore, improvement and generalisation of some ancillary tests, such as diagnostic antibodies for neuromyelitis optica, allows better phenotyping of the heterogeneous inflammatory optic neuropathies.