Optic Atrophy Report Summary

Optic Atrophy Report Summary

Author or authors of report : Syed Shoeb Ahmad; Venkata M. Kanukollu.
Date of report : 2022-08-08

Definition

Optic atrophy is the hallmark of damage to the visual pathway, appearing as a pale disc on fundus examination. It is not a disease in itself but indicates damage to the anterior visual pathway, which can occur due to various conditions.

Introduction

Optic atrophy refers to the shrinkage of the optic nerve due to the degeneration of retinal ganglion cell (RGC) axons. The term "optic atrophy" is sometimes considered a misnomer, with "optic neuropathy" being a more accurate term. However, this is also debated. The optic nerve behaves more like a white matter tract than a peripheral nerve. The optic nerve head undergoes degeneration, contributing to the pallor of the optic disc seen in optic atrophy. The exact mechanisms causing the optic disc pallor in optic atrophy are not fully understood, but it is believed to be due to the loss of axonal fibers and the rearrangement of astrocytes.

Etiology

The risk factors for optic atrophy can be remembered using the mnemonic: VIN DITTCH MD. This represents Vascular, Inflammatory and infectious, Neoplastic or compressive, Primary demyelinating disease or idiopathic optic neuritis, Toxic and traumatic, Congenital, Hereditary, Metabolic and endocrine causes, and Degenerative. A study in Malaysia found the main causes to be space-occupying intracranial lesions, congenital/hereditary diseases, hydrocephalus, trauma, and vascular causes. Optic atrophy can also be classified based on its causes, including congenital optic neuropathies, optic atrophy associated with systemic disease or neurological conditions, extrinsic compression, intrinsic optic nerve tumors, vascular disease, inflammatory disease, infection, toxic and nutritional optic neuropathies, trauma, swollen optic nerve, and retinal disease.

Epidemiology

The prevalence of optic atrophy varies across countries. It was a significant cause of blindness in studies from Israel, Japan, Scotland, Zaire, and other countries. In Oman, 5% of blindness was due to this condition. In southern Germany, the incidence rate per 100,000 person-years for optic atrophy was 2.86. In the US, the prevalence of blindness due to optic atrophy in whites was zero, while it was 1.9% in African-Americans.

Pathophysiology

The optic nerve head is where the axons of the RGCs exit the eyeball. The arterial supply to this segment is from the retinal arterioles. The degeneration of RGCs, axons, and capillaries leads to the pale optic disc seen in optic atrophy.

Histopathology

In optic atrophy, there are certain histopathological changes, including the widening of the pial septa and subarachnoid space with a redundancy of the dura. In cases of trauma, the anterior severed ends of the nerve show bulbous swellings known as Cajal end bulbs.

History and Physical

Patients with optic atrophy often report vision loss with segmental or diffuse blurring of the visual field. History should focus on the suspected cause of visual impairment. Optic neuritis, an important cause of optic atrophy, typically affects individuals between 10-50 years of age. On examination, reduced visual acuity and contrast sensitivity may be observed, along with a relative afferent pupillary defect.