the optic nerve passes through the optic disc to enter the eye.
the optic nerve passes through the optic disc to enter the eye.
where does the optic nerve pass through to enter the eye?
optic disc
optic nerve hypoplasia









































optic nerve hypoplasia (onh) is a medical condition arising from the underdevelopment of the optic nerve(s). this condition is the most common congenital optic nerve anomaly. the optic disc appears abnormally small, because not all the optic nerve axons have developed properly. it is often associated with endocrinopathies (hormone deficiencies), developmental delay, and brain malformations. the optic nerve, which is responsible for transmitting visual signals from the retina to the brain, has approximately 1.2 million nerve fibers in the average person. in those diagnosed with onh, however, there are noticeably fewer nerves.









































section::::symptoms.
optic nerve hypoplasia
the optic nerve can be damaged when exposed to direct or indirect injury. direct optic nerve injuries are caused by trauma to the head or orbit that crosses normal tissue planes and disrupts the anatomy and function of the optic nerve; e.g., a bullet or forceps that physically injures the optic nerve. indirect injuries, like blunt trauma to the forehead during a motor vehicle accident, transmit force to the optic nerve without transgressing tissue planes. this type of force causes the optic nerve to absorb excess energy at the time of impact. the most common site of injury of the optic nerve is the intracanalicular portion of the nerve. deceleration injuries from motor vehicle or bicycle accidents account for 17 to 63 percent of cases. falls are also a common cause, and optic neuropathy most commonly occurs when there is a loss of consciousness associated with multi-system trauma and serious brain injury. in less than three percent of patients, an orbital hemorrhage after an injection behind the eye (retrobulbar block) can cause injury to the optic nerve, but this is readily manageable if it does not involve direct optic nerve injury and is caught early. the role of high-dose steroids and orbital decompression in treating these patients is controversial and, if administered, must be done very soon after injury with minimal effects. in patients with an orbital fracture, vomiting or nose blowing can force air into the orbit and possibly compromise the integrity of the optic nerve.
optic neuropathy