Optic nerve head

Optic Nerve Head

Optic nerve head and surrounding structures (Gray's Anatomy)

The Optic Nerve Head (ONH), also known as the optic disc, is the point of exit for ganglion cell axons leaving the eye. It is a crucial structure in the visual system, playing a significant role in many ocular diseases, including glaucoma and optic neuritis.

Anatomy

The ONH is a small, circular area in the back of the eye where the optic nerve connects to the retina. It is approximately 1.5 mm in diameter and is located in the nasal part of the retina, slightly above the horizontal midline.

The ONH is divided into several regions: the optic disc, the optic cup, and the optic rim. The optic disc is the central region of the ONH and is devoid of photoreceptor cells, resulting in a physiological blind spot. The optic cup is a small depression in the center of the optic disc, and the optic rim is the remaining neural tissue surrounding the optic cup.

Clinical significance

The appearance of the ONH can provide valuable information about the health of the eye and the visual system. Changes in the size, shape, or color of the ONH can indicate the presence of ocular diseases such as glaucoma or optic neuritis. In glaucoma, increased intraocular pressure can cause damage to the optic nerve fibers, leading to a characteristic cupping of the optic disc. In optic neuritis, inflammation of the optic nerve can cause swelling of the ONH, which can be seen during an ophthalmoscopic examination.

See also

• Optic nerve
• Glaucoma
• Optic neuritis
• Ophthalmoscopy