The Pale Optic Disc

What is it?

Optic disc rim appears white rather than reddish pink on ophthalmoscopy
Trap: the normal color of the optic disc varies greatly, so that calling an optic disc “pale” on the basis of ophthalmoscopy can be fraught

Normal optic disc that appears pale by ophthalmoscopy
- Less prominent optic disc capillaries
- Pseudophakia eliminates the brownish tint of the native lens in older adults
- Trap: the normal brownish tint of the ocular media in phakic patients can make a pale optic disc appear normal
- Tilting of the optic disc in myopia creates temporal optic disc pallor

To differentiate optic disc pallor from normal, correlate with visual function measures and other neuro-ophthalmic abnormalities

Look for the following characteristic distributions of optic disc pallor
- Superior or inferior optic disc pallor: suggests segmental infarction in ischemic optic neuropathy
- Symmetrical temporal optic disc pallor in both eyes: suggests toxic/metabolic/hereditary optic neuropathy
Trap: ophthalmoscopy alone is often insufficient to determine the cause of optic disc pallor

Optic disc pallor is merely a sign of optic nerve axon loss, which can result from disease in the inner retina, optic nerve, optic chiasm, optic tract, or lateral geniculate body
Trap: lesions of the inner retina, optic nerve, optic chiasm, optic tract, or lateral geniculate bodies can exist without causing optic disc pallor, especially if the insult is mild or recent
Tip: optical coherence tomography may assist in confirming atrophy of the optic disc or inner retina
Retrobulbar imaging is often indicated to determine the cause of optic disc pallor