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Topic

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Optic disc

The optic disc, also known as the optic nerve head, is a critical anatomical structure located at the posterior aspect of the eye, where the optic nerve fibers exit the retina and enter the brain. This region represents the point of convergence for ganglion cell axons and lacks photoreceptors, resulting in the physiological blind spot. The optic disc is a crucial landmark in ophthalmology and neuroimaging, as it is frequently assessed for signs of optic nerve pathology, increased intracranial pressure, and systemic diseases.

Synonyms

  • Optic nerve head

  • Optic papilla

  • Blind spot (functional synonym)

Function

  • Serves as the exit point for ganglion cell axons leaving the retina to form the optic nerve

  • Entry and exit site for the central retinal artery and vein

  • Acts as a vital anatomical and clinical landmark in fundoscopic and neuroimaging evaluations

  • Plays a role in vision by transmitting visual information from the retina to the brain, although it itself is insensitive to light

MRI Appearance

T1-Weighted Imaging

  • Optic disc appears isointense to the optic nerve

  • Surrounded by slightly hyperintense orbital fat

  • Central vessels (central retinal artery and vein) may be visible as flow voids

T2-Weighted Imaging

  • Optic disc and optic nerve appear isointense to brain parenchyma

  • Cerebrospinal fluid (CSF) within the optic nerve sheath appears hyperintense

  • Perioptic subarachnoid space (around the optic nerve) is easily distinguished due to high T2 signal

STIR (Short Tau Inversion Recovery) Imaging

  • Fat suppression improves visualization of the optic disc and nerve

  • The optic disc appears hypointense to surrounding orbital fat

  • Useful for detecting inflammatory or edematous changes (e.g., optic neuritis)

CT Appearance

  • Optic disc is not well visualized as a discrete structure on non-contrast CT due to limited soft tissue resolution

MRI images

Optic disc mri image