Optic disc drusen are found clinically in about 1% of the population but this increases to 3.4% in individuals with a family history of ODD. About two thirds to three quarters of clinical cases are bilateral. A necropsy study of 737 cases showed a 2.4% incidence with 2 out of 15 (13%) bilateral, perhaps indicating the insidious nature of many cases. An autosomal dominant inheritance pattern with incomplete penetrance and associated inherited dysplasia of the optic disc and its blood supply is suspected. Males and females are affected at equal rates. Caucasians are the most susceptible ethnic group. Certain conditions have been associated with disc drusen such as retinitis pigmentosa, angioid streaks, Usher syndrome, Noonan syndrome and Alagille syndrome. Optic disc drusen are not related to Bruch membrane drusen of the retina which have been associated with age-related macular degeneration.

About 1–2% of all meningiomas are optic nerve sheath meningiomas. Meningiomas have an incidence of ~4.18/100,000 persons each year. Thus, ~10,000 meningiomas are diagnosed in the US each year; corresponding to ~100 cases of ONSM each year in the US. The actual number of meningiomas is likely much higher as it is very common in elderly women. ONSM comprises about 2% of orbital tumors, and about 10% of optic nerve lesions.

Neurofibromatosis type II (NF-2) affects around 9% of ONSM patients, where the incidence in the general population is around 0.03–0.05%. Thus NF-2 is felt to be a risk factor for the development of ONSM.

No particular risk factors have been conclusively identified; however, there have been a few reports that demonstrate an autosomal dominant pattern of inheritance in some families. Therefore, a family history of optic pits may be a possible risk factor.

Disc herniation can occur in any disc in the spine, but the two most common forms are lumbar disc herniation and cervical disc herniation. The former is the most common, causing lower back pain (lumbago) and often leg pain as well, in which case it is commonly referred to as sciatica. Lumbar disc herniation occurs 15 times more often than cervical (neck) disc herniation, and it is one of the most common causes of lower back pain. The cervical discs are affected 8% of the time and the upper-to-mid-back (thoracic) discs only 1–2% of the time.

The following locations have no discs and are therefore exempt from the risk of disc herniation: the upper two cervical intervertebral spaces, the sacrum, and the coccyx. Most disc herniations occur when a person is in their thirties or forties when the nucleus pulposus is still a gelatin-like substance. With age the nucleus pulposus changes ("dries out") and the risk of herniation is greatly reduced. After age 50 or 60, osteoarthritic degeneration (spondylosis) or spinal stenosis are more likely causes of low back pain or leg pain.

- 4.8% males and 2.5% females older than 35 experience sciatica during their lifetime.

- Of all individuals, 60% to 80% experience back pain during their lifetime.

- In 14%, pain lasts more than 2 weeks.

- Generally, males have a slightly higher incidence than females.

An inheritable gene variation may cause increased susceptibility. People with a variation in a gene that encodes the cartilage intermediate-layer protein (CILP) were 1.6 times more likely to have the disease than persons without the variation. CILP is a normal component of disc tissue. The gene variant was hypothesized to disrupt normal building and maintenance of cartilage. However, this association was not replicated in a follow-up study of Finnish and Chinese individuals.

Surgery may be useful in those with a herniated disc that is causing significant pain radiating into the leg, significant leg weakness, bladder problems, or loss of bowel control. Discectomy (the partial removal of a disc that is causing leg pain) can provide pain relief sooner than nonsurgical treatments. Discectomy has better outcomes at one year but not at four to ten years. The less invasive microdiscectomy has not been shown to result in a significantly different outcome than regular discectomy with respect to pain. It might however have less risk of infection.

The presence of cauda equina syndrome (in which there is incontinence, weakness and genital numbness) is considered a medical emergency requiring immediate attention and possibly surgical decompression. Regarding the role of surgery for failed medical therapy in people without a significant neurological deficit, a Cochrane review concluded that "limited evidence is now available to support some aspects of surgical practice".

Optic pits occur equally between men and women. They are seen in roughly 1 in 10,000 eyes, and approximately 85% of optic pits are found to be unilateral (i.e. in only one eye of any affected individual). About 70% are found on the temporal side (or lateral one-half) of the optic disc. Another 20% are found centrally, while the remaining pits are located either superiorly (in the upper one-half), inferiorly (in the lower one-half), or nasally (in the medial one-half towards the nose).

Initial treatment in lumbar disc disease is one or two days of bedrest (although growing number of studies shows that it makes little difference) and pain relieving medications. In cases with ongoing pain despite conservative treatments, a surgical operation that will remove the compressing disc material, a microdiscectomy or discectomy may be recommended to treat a lumbar disc herniation.

The morning glory disc anomaly (MGDA) is a congenital deformity resulting from failure of the optic nerve to completely form in utero. The term was coined in 1970 by Kindler, noting a resemblance of the malformed optic nerve to the morning glory flower. The condition is usually unilateral.

On fundoscopic examination, there are three principal findings comprising the anomaly:

1. an enlarged, funnel-shaped excavation in optic disc

2. an annulus or ring of pigmentary changes surrounding the optic disc excavation

3. a central glial tuft overlying the optic disc

Perioperative PION patients have a higher prevalence of cardiovascular risk factors than in the general population. Documented cardiovascular risks in people affected by perioperative PION include high blood pressure, diabetes mellitus, high levels of cholesterol in the blood, tobacco use, abnormal heart rhythms, stroke, and obesity. Men are also noted to be at higher risk, which is in accordance with the trend, as men are at higher risk of cardiovascular disease. These cardiovascular risks all interfere with adequate blood flow, and also may suggest a contributory role of defective vascular autoregulation.

Optic disc drusen (ODD) or optic nerve head drusen (ONHD) are globules of mucoproteins and mucopolysaccharides that progressively calcify in the optic disc. They are thought to be the remnants of the axonal transport system of degenerated retinal ganglion cells.

ODD have also been referred to as congenitally elevated or anomalous discs, pseudopapilledema, pseudoneuritis, buried disc drusen, and disc hyaline bodies. They may be associated with vision loss of varying degree occasionally resulting in blindness.

It is estimated that the incidence of AION is about 8,000/year in the U.S.

Although many perinatal and prenatal risk factors for ONH have been suggested, the predominant, enduring, most frequent risk factors are young maternal age and primiparity (the affected child being the first child born to the mother). Increased frequency of delivery by caesarean section and fetal/neonatal complications, preterm labor, gestational vaginal bleeding, low maternal weight gain, and weight loss during pregnancy are also associated with ONH.

Coloboma of optic nerve, is a rare defect of the optic nerve that causes moderate to severe visual field defects.

Coloboma of the optic nerve is a congenital anomaly of the optic disc in which there is a defect of the inferior aspect of the optic nerve. The issue stems from incomplete closure of the embryonic fissure while in utero. A varying amount of glial tissue typically fills the defect, manifests as a white mass.

The mechanism of injury for NAION used to be quite controversial. However, experts in the field have come to a consensus that most cases involve two main risk factors. The first is a predisposition in the form of a type of optic disc shape. The optic disc is where the axons from the retinal ganglion cells collect into the optic nerve. The optic nerve is the bundle of axons that carry the visual signals from the eye to the brain. This optic nerve must penetrate through the wall of the eye, and the hole to accommodate this is usually 20-30% larger than the nerve diameter. In some patients the optic nerve is nearly as large as the opening in the back of the eye, and the optic disc appears "crowded" when seen by ophthalmoscopy. A crowded disc is also referred to as a "disc at risk". While a risk factor, the vast majority of individuals with crowded discs do not experience NAION.

The second major risk factor involves more general cardiovascular risk factors. The most common are diabetes, hypertension and high cholesterol levels. While these factors predispose a patient to develop NAION, the most common precipitating factor is marked fall of blood pressure during sleep (nocturnal arterial hypotension)- that is why at least 75% of the patients first discover visual loss first on waking from sleep. These vascular risk factors lead to ischemia (poor blood supply) to a portion of the optic disc. The disc then swells, and in a crowded optic disc, this leads to compression and more ischemia.

Since both eyes tend to have a similar shape, the optometrist or ophthalmologist will look at the good eye to assess the anatomical predisposition. The unaffected eye has a 14.7% risk of NAION within five years.

A number of uncontrolled single case or small number of patient reports have associated NAION with use of oral erectile dysfunction drugs.

Optic nerve sheath meningiomas (ONSM) are rare benign tumors of the optic nerve. 60–70% of cases occur in middle age females, and is more common in older adults (mean age 44.7 years). It is also seen in children, but this is rare. The tumors grow from cells that surround the optic nerve, and as the tumor grows, it compresses the optic nerve. This causes loss of vision in the affected eye. Rarely, it may affect both eyes at the same time.

It is typically a slow growing tumor, and has never been reported to cause death. However, there is concern that the tumor can grow into the brain and cause other types of neurological damage. In some patients, the tumor grows so slowly that treatment is not necessary. Standard treatments are observation, surgery, radiation therapy, and combinations of the above.

Although the finding itself is rare, MGDA can be associated with midline cranial defects and abnormal carotid circulation, such as carotid stenosis/aplasia or progressive vascular obstruction with collateralization (also known as moyamoya disease). The vascular defects may lead to ischemia, stroke, or seizures and so a finding of MGDA should be further investigated with radiographic imaging.

As the optic nerve sheath is continuous with the subarachnoid space of the brain (and is regarded as an extension of the central nervous system), increased pressure is transmitted through to the optic nerve. The brain itself is relatively spared from pathological consequences of high pressure. However, the anterior end of the optic nerve stops abruptly at the eye. Hence the pressure is asymmetrical and this causes a pinching and protrusion of the optic nerve at its head. The fibers of the retinal ganglion cells of the optic disc become engorged and bulge anteriorly. Persistent and extensive optic nerve head swelling, or optic disc edema, can lead to loss of these fibers and permanent visual impairment.

Papilledema (or papilloedema) is optic disc swelling that is caused by increased intracranial pressure. The swelling is usually bilateral and can occur over a period of hours to weeks. Unilateral presentation is extremely rare. Papilledema is mostly seen as a symptom resulting from another pathophysiological process.

In intracranial hypertension, the optic disc swelling most commonly occurs bilaterally. When papilledema is found on fundoscopy, further evaluation is warranted due to the fact that vision loss can result if the underlying condition is not treated. Further evaluation with a CT or MRI of the brain and/or spine is usually performed. Recent

research has shown that point-of-care ultrasound can be used to measure optic nerve sheath diameter for detection of increased intracranial pressure and shows good diagnostic test accuracy compared to CT. Thus, if there is a question of papilledema on fundoscopic examination or if the optic disc cannot be adequately visualized, ultrasound can be used to rapidly assess for increased intracranial pressure and help direct further evaluation and intervention. Unilateral papilledema can suggest a disease in the eye itself, such as an optic nerve glioma.

"Idiopathic" means of unknown cause. Therefore, IIH can only be diagnosed if there is no alternative explanation for the symptoms. Intracranial pressure may be increased due to medications such as high-dose vitamin A derivatives (e.g. isotretinoin for acne), long-term tetracycline antibiotics (for a variety of skin conditions) and hormonal contraceptives. There are numerous other diseases, mostly rare conditions, that may lead to intracranial hypertension. If there is an underlying cause, the condition is termed "secondary intracranial hypertension". Common causes of secondary intracranial hypertension include obstructive sleep apnea (a sleep-related breathing disorder), systemic lupus erythematosus (SLE), chronic kidney disease, and Behçet's disease.

As illustrated by the risk factors above, perioperative hypoxia is a multifactorial problem. Amidst these risk factors it may be difficult to pinpoint the optic nerve’s threshold for cell death, and the exact contribution of each factor.

Low blood pressure and anemia are cited as perioperative complications in nearly all reports of PION, which suggests a causal relationship. However, while low blood pressure and anemia are relatively common in the perioperative setting, PION is exceedingly rare. Spine and cardiac bypass surgeries have the highest estimated incidences of PION, 0.028% and 0.018% respectively, and this is still extremely low. This evidence suggests that optic nerve injury in PION patients is caused by more than just anemia and low blood pressure.

Evidence suggests that the multifactorial origin of perioperative PION involves the risks discussed above and perhaps other unknown factors. Current review articles of PION propose that vascular autoregulatory dysfunction and anatomic variation are under-investigated subjects that may contribute to patient-specific susceptibility.

Vision in the affected eye is impaired, the degree of which depends on the size of the defect, and typically affects the visual field more than visual acuity. Additionally, there is an increased risk of serous retinal detachment, manifesting in 1/3 of patients. If retinal detachment does occur, it is usually not correctable and all sight is lost in the affected area of the eye, which may or may not involve the macula.

A 1994 community-based study indicated that two out of every 100,000 people suffered from SCSFLS, while a 2004 emergency room-based study indicated five per 100,000. SCSFLS generally affects the young and middle aged; the average age for onset is 42.3 years, but onset can range from ages 22 to 61. In an 11-year study women were found to be twice as likely to be affected as men.

Studies have shown that SCSFLS runs in families and it is suspected that genetic similarity in families includes weakness in the dura mater, which leads to SCSFLS. Large scale population-based studies have not yet been conducted. While a majority of SCSFLS cases continue to be undiagnosed or misdiagnosed, an actual increase in occurrence is unlikely.

A spontaneous CSF leak is idiopathic, meaning the cause in unknown. Various scientists and physicians have suggested that this condition may be the result of an underlying connective tissue disorder affecting the spinal dura. It may also run in families and be associated with aortic aneurysms and joint hypermobility. Up to two thirds of those afflicted demonstrate some type of generalized connective tissue disorder. Marfan syndrome, Ehlers-Danlos syndrome and autosomal dominant polycystic kidney disease are the three most common connective tissue disorders associated with SCSFLS.

Roughly 20% of patients with SCSFLS exhibit features of Marfan syndrome, including tall stature, hollowed chest (pectus excavatum), joint hypermobility and arched palate. However these patients do not exhibit any other Marfan syndrome presentations.

The development of accurate and reliable non-invasive ICP measurement methods for VIIP has the potential to benefit many patients on earth who need screening and/or diagnostic ICP measurements, including those with hydrocephalus, intracranial hypertension, intracranial hypotension, and patients with cerebrospinal fluid shunts. Current ICP measurement techniques are invasive and require either a lumbar puncture, insertion of a temporary spinal catheter, insertion of a cranial ICP monitor, or insertion of a needle into a shunt reservoir.