Optic atrophy refers to pathological changes in retinal ganglion cells and their axons caused by various diseases. It generally involves degeneration of ganglion cell axons occurring between the retina and the lateral geniculate nucleus.
Etiology
The main causes include:
- Increased intracranial pressure or intracranial inflammation: Causes lesions in the optic nerve, optic chiasm, and optic tract, such as late-stage optic disc edema or tuberculous meningitis.
- Retinal diseases: Includes vascular conditions (central retinal artery or vein occlusion), inflammatory conditions (retinochoroiditis), and degenerative conditions (retinitis pigmentosa).
- Optic nerve diseases: Includes vascular causes (ischemic optic neuropathy), inflammatory causes (optic neuritis), toxic or syphilitic optic neuropathy, and glaucoma-related damage.
- Compressive lesions: Includes orbital tumors, hemorrhage, and intracranial tumors.
- Traumatic injuries: Occurs due to trauma to the skull or orbit.
- Metabolic disorders: Includes diabetes.
- Hereditary diseases: Includes Leber hereditary optic neuropathy.
- Nutritional deficiencies: Includes vitamin B deficiency.
Fundoscopic Manifestations
Based on fundoscopic findings, optic atrophy is classified into two main types: primary and secondary.
Primary Optic Atrophy
This type results from damage to the optic nerve, optic chiasm, optic tract, or lateral geniculate body, with atrophy occurring in a descending manner. The optic disc appears pale or white, with clear boundaries. The optic cup reveals visible sieve-like pores, and the retinal vessels generally remain normal. Recent studies have shown that damage to the visual pathways beyond the lateral geniculate body, such as the occipital lobe cortex, can also lead to retinal nerve fiber layer and ganglion cell loss, a process referred to as retrograde neuronal degeneration.
Secondary Optic Atrophy
This type is caused by primary lesions in the optic disc, retina, or choroid, with atrophy progressing in an ascending manner (anterograde degeneration). The optic disc appears grayish-white and dull with blurred boundaries, and the physiological optic cup becomes obliterated. The retinal arteries appear narrowed, and vessels often exhibit whitish sheathing. Hard exudates or residual hemorrhages may be present in the posterior pole.
Diagnosis
The temporal side of a normal optic disc typically appears lighter in color than the nasal side, and the optic disc in infants has a naturally pale appearance. Therefore, a diagnosis of optic atrophy cannot be based solely on optic disc discoloration. It is necessary to evaluate visual acuity, visual fields, and optical coherence tomography (OCT) findings. Observing the retinal nerve fiber layer can aid in the early detection of optic atrophy.
While diagnosing optic atrophy based on fundoscopic findings is relatively straightforward, determining the cause of primary optic atrophy often requires multiple auxiliary tests such as visual field analysis, OCT, visual electrophysiology, CT, or MRI. Neurological evaluations may also be required to identify underlying causes.
Treatment
There are no specific cures for optic atrophy at present. Management priorities involve treating the underlying condition. Partial vision recovery may be possible after surgery for most cases of optic atrophy caused by compression from pituitary tumors. Timely surgical intervention for conditions such as orbital tumors, hematomas, thyroid-associated ophthalmopathy, or optic nerve canal fractures may also yield favorable outcomes. For optic atrophy caused by other factors, neurotrophic drugs and vasodilators may be considered for treatment.