Clinical approach to optic neuropathies

Abstract

Optic neuropathy is a frequent cause of vision loss encountered by ophthalmologist. The diagnosis is made on clinical grounds. The history often points to the possible etiology of the optic neuropathy. A rapid onset is typical of demyelinating, inflammatory, ischemic and traumatic causes. A gradual course points to compressive, toxic/nutritional and hereditary causes. The classic clinical signs of optic neuropathy are visual field defect, dyschromatopsia, and abnormal papillary response. There are ancillary investigations that can support the diagnosis of optic neuropathy. Visual field testing by either manual kinetic or automated static perimetry is critical in the diagnosis. Neuro-imaging of the brain and orbit is essential in many optic neuropathies including demyelinating and compressive. Newer technologies in the evaluation of optic neuropathies include multifocal visual evoked potentials and optic coherence tomography.

Keywords: Leber’s optic neuropathy; arteritic anterior ischemic optic neuropathy (AION); dominant optic atrophy; multiple sclerosis; non-arteritic anterior ischemic optic neuropathy (NAION); optic neuritis; optic neuropathy; optical coherence tomography; radiation optic neuropathy; recessive optic atrophy; traumatic optic neuropathy.

Figure 1

(A) Axial MRI of the brain (FLAIR sequence) showing the classic periventricular white matter lesions seen in MS. (B) Sagittal MRI showing peri-collosal white matter lesions also known as “Dawson’s fingers”.

Figure 2

An 11 year old boy with sudden onset of visual loss 2 weeks following a viral upper respiratory tract infection. Bilateral disc swelling was seen in the right (A) and left (B) disc. Visual acuity improved over 1 week spontaneously from counting fingers to 20/20 in both eyes.

Figure 3

A 57 year old patient with history of hypertension, diabetes and hypercholesterolemia and NAION in his right eye. There is pallid swelling of the right disc with hemorrhage superiorly. The left optic disc has a cup to disc ratio of 0.1 (not shown).

Figure 4

Disc swelling in GCA. Note pallid disc swelling with hemorrhages and an adjacent area of choroidal infarction (arrow) (courtesy of Peter J Savino, MD).

Figure 5

A 55 year old women with chronic disc swelling and optic neuropathy in the right eye. MRI showed enhancement of the intracranial nerve. An extensive work up, including a spinal tap, was negative. An optic nerve sheath biopsy showed optic nerve lymphoma with no systemic involvement.

Figure 6

An axial contrast-enhanced MRI of the orbit showing enhancement of the intra-orbital and intra-canalicular optic nerve in a lady with optic nerve sheath meningioma in the right eye.

Figure 7

A 55 year old lady carrier of the 3460 G LHON mitochondrial mutation, with bilateral disc swelling (top figure). Automated 24–2 perimetry (middle figure) shows bilateral arcuate defects and 10–2 perimetry shows bilateral central scotomas (bottom figure). The patient is a carrier the 3460 G LHON mitochondrial mutation.