It is also called the second cranial nerve or cranial nerve II. . of the retinal arterioles is necessary if the optic disc edema is to be correctly interpreted as the initial symptom of hypertensive retinopathy. The disorder largely follows a sex-linked hereditary pattern. This site needs JavaScript to work properly. The optic disc is then ill defined and hyperemic. The causes of optic nerve inflammation include: Most people with optic neuritis recover without treatment, but medications may be necessary to speed up recovery and prevent vision loss. The neurosensory rim is the tissue between the margin of the cup and the edge of the disk, and is composed of the ganglion cell axons from the retina. The optic nerve is located in the back of the eye. - Optic neuritis refers to inflammation of the optic nerve often in association with a demyelinating illness such as multiple sclerosis. The prognosis for visual acuity is extremely poor. Learn about LASIK success rates and side effects, Learn about the costs associated with LASIK, Benefits of LASIK for astigmatism correction, How to find vision insurance that covers LASIK, Compare PRK and LASIK procedures and results, 14 tips for protecting your vision after LASIK. This high pressure compresses the optic nerve and causes cells to die. Other compressive lesions, such as pituitary adenomas and . It is associated with a sudden decrease in visual acuity. eCollection 2021 Jan-Mar. All rights reserved. The intracanalicular part of CN II lies in a watershed area supplied by the collaterals ophthalmic artery (anteriorly) and pial derivatives of the superior hypophyseal and internal carotid arteries (posteriorly). Br J Ophthalmol. arterial hypertension (55% of all patients), diabetes mellitus without retinopathy (23% of all patients). Optic disc photographs were independently graded by three ophthalmologists in a standardised manner. Reading time: 30 minutes. Optic nerve melanocytomas are benign tumors but may cause vision loss and visual field defects. They can produce a sharp echo on ultrasound images. The bipolar cells permit communication between the photoreceptors and the ganglion cells. This disorder is attributable to giant cell arteritis. The nerve extends after the optic chiasm to form the lateral geniculate nucleus (LGN).5 The LGN is the point of origin for optic radiations (ORs), which connect the optic nerve to the brain. The optic disc is then ill defined and hyperemic. On fluorescein angiography, the capillaries visible in the optic disc fill as in a normal angiogram. Although their growth is slow but progressive, their location is critical as it directly affects the anterior visual pathway and can lead to a severe visual loss. Patients suffer headache, nausea, vomiting transient obscuration of vision, and as disease progresses increasing defects in the periphery of the visual fields. There are various pathological processes that can affect the optic nerve. The symptoms of optic nerve issues may vary depending on the underlying condition. However, it has since been discovered that the optic nerve is in fact level with the retina, therefore the term papilla is an old erroneous word that is still used occasionally with reference to the head of the optic nerve. left visual field). Children of diseased men are clinically normal. The vast majority of optic nerve fibres convey information regarding central vision. The extra length (in addition to the length of the intraorbital component) permits additional movements of the eyeball within the orbit. Elizabeth O. Johnson, PhD Many aspects concerning the final anatomic appearance of the optic nerve head have been explained. The following are health conditions that can damage the optic nerve and affect vision. Accuracy of a Deep Learning System for Classification of Papilledema Severity on Ocular Fundus Photographs. Clinically, this phenomenon is observed as blurring of the optic disc margins and the disc appears hyperaemic on funduscopic examination. the macula) will project to the posterior third of the primary visual cortex. The lamina cribrosa has concave and convex surfaces anteriorly and posteriorly, respectively. At the periphery, the transverse septae attach the pia mater to the posterior aspect of the lamina cribrosa. Anatomy. Thus, the term " papilledema" should not be applied indiscriminately .Idiopathic intracranial hypertension (pseudotumor cerebri): Prognosis and treatment. Posterior Capsule Opacification of the Optic Nerve Head Posterior Capsule Opacification The lens capsule is the thin, elastic-like bag that holds the intraocular lens (IOL) in position after cataract surgery. The degree of visual loss is variable, ranging from minimal if any visual loss to complete absence of light perception. Normal Optic Nerve Underneath the optic chiasm sits the pituitary gland. Optic atrophy in one eye and disc swelling in the other may result from asymmetric optic nerve compression or from tumor-induced direct optic nerve compression in one eye and papilledema from increased intracranial pressure in the other (Foster Kennedy syndrome) (see Chapter 4 ). The vagus nerve is the longest of the 12 cranial nerves. Optic nerve damage may affect one or both eyes. The optic nerve is responsible for relaying information to the pretectal nucleus at the level of the superior colliculus, which is responsible for bilateral regulation of the activity of the Edinger-Westphal nucleus (parasympathetic nucleus of CN III). The optic nerve receives its blood supply through the posterior ciliary artery (PCA) . It is a unique structure that functions as the bridge between the retinal layer of the eyes and the visual cortex of the brain. The 25 mm of optic nerve travelling from the posterior part of the eyeball (a few millimetres medial to its posterior pole) to the intraorbital opening of the optic canal is known as the intraorbital part. Papilledema does not initially impair vision. ORs relay visual information to the brain for processing. Optic disc findings are identical in both eyes. Although OCT dates to the early 1990s, the introduction of the Stratus OCT (Carl Zeiss Meditec) in 2001the original time-domain technologymarks when OCT became widely accessible. Growth and development of the optic nerve continues into adolescent years. Proper diagnosis is therefore very important. Fibers of Baums loop pass directly through the parietal lobeto enter the retrolentiform part of the internal capsule. Therefore, increased intracranial pressure acts on the optic nerve to produce visible changes in the optic disc. Keywords: Fig. Recall that the retina can be subdivided into nasal and temporal halves, which can be further subdivided into superior and inferior poles. A spectrum of conditions can affect the ONH ranging from optic disc swelling in life threatening intracranial space occupying lesions to minor morphological and congenital variations. Background: The normal optic nerve head varies from one person to another, and there is often intraindividual variation as well. It is otherwise structurally identical to the preceding intraorbital segment. The prominence is measured in diopters on direct ophthalmoscopy or in millimeters on ultrasound. Optic Nerve Appearance The upper and lower visual fields are also topographically mapped onto the lateral geniculate body and visual cortex. The surface nerve fiber layer is highly vascular with numerous capillary networks, and large retinal arteries and veins course through it. Often central retinal artery occlusion will be present with an ischemic edema. Optic nerve branches are sections of the optic nerve that travel to your brain or connect to other fibers responsible for vision. It is also called the second cranial nerve or cranial nerve II. It is separated from the overlying arachnoid mater by cerebrospinal fluid . It extends from the internal orifice of the optic canal and travels above the diaphragma sellae before passing above the suprasellar part of the cavernous sinus. This disease of the optic nerve usually occurs in older patients; the average age is 65. Treatment: discontinue amiodarone therapy. Causes of blurred and hyperemic optic discs: The optic nerve sheath connects the optic disc with the subarachnoid space. The optic nerve is part of the eye, the central nervous system (CNS), and one of the 12 cranial nerve pairs. We may earn commissions if you purchase something via one of our links. The pupil responds as in amblyopia. Fig. There is some degree of variability in the blood supply of the optic nerve depending on the segment of the nerve being discussed. Papilledema (papilloedema) refers to the swelling of the optic nerve head (optic disc) due to increased intracranial pressure (pressure inside the brain).11 In most cases, both eyes are affected. According to statistics from the Center for Disease Control (CDC), glaucoma affects 3 million Americans and is one of the leading causes of vision loss globally.6. The vessels travel anteriorly in the substance of the optic nerve after they pierce the structure roughly 10 12 mm from the globe. , National Center for Biotechnology Information (NCBI), 6 Oct. 2020. Elevation of the optic disc is 2 diopters. These may include: Brain tumor. Acquired optic neuropathies can be classi ed according to whether the optic disc appears normal, sw ollen, or pale. Leber hereditary optic neuropathy usually occurs in both eyes in rapid succession. The most pathological form of a small optic disc is called papillary aplasia ( Fig. It originates near the nose. The information we provide is grounded on academic literature and peer-reviewed research. Author: The next section lists some of . The optic nerve or optic disc may also be evaluated by using . Its enclosed by a layer of glial cells known as oligodendrocytes, which are for support and insulation of brain tissues. However, the nerve becomes more closely related to the annulus of Zinn, where the four recti originate. hypercholesterolemia (36% of all patients). Arteritic anterior ischemic optic neuropathy progresses far more rapidly than the arteriosclerotic type. Tobacco-alcohol amblyopia is a toxic bilateral optic neuropathy attributed to abuse of ethyl alcohol and tobacco. There are intervening connective tissue septae that contain vascular entities travelling longitudinally and transversely. The optic nerve can also be damaged by shock, toxins, radiation, and trauma. government site. This means that the mutation is apparently transmitted in the cytoplasm of the maternal ovum. Glaucoma is one of the most common illnesses affecting the optic nerve. Through her writing, Dr. Huang enjoys educating patients on how to lead healthier and happier lives. The optic nerve is the second ( CN II ) cranial nerve ( TA: nervus opticus or nervus cranialis II). A complete diagnosis is based on optic nerve appearance, tests of visual function (visual field, contrast . Clipboard, Search History, and several other advanced features are temporarily unavailable. Fig. The major ones discussed here are related to disorders of circulation, intraocular pressure, or inflammation of the nerve. The identity of cranial nerve II (CN II), also known as the optic nerve, predates Galenic anatomy. Bethesda, MD 20894, Web Policies Wall M, Thurtell MJ; NORDIC Idiopathic Intracranial Hypertension Study Group. It begins with optic disc edema. It has numerous clinical correlates, including neurologic and endocrine pathologies, making timely clinical . Often, there can be associated colobomas of the iris and/or ciliary body. The optic chiasm marks an important part of CN II. These are drusen. The optic nerve is responsible for transmitting visual information to the brain for interpretation. The optic nerve is made of ganglionic cells or nerve cells. There are many different causes of swelling of the optic disc that require different treatments. Your eye doctor can sometimes see the bumpy appearance of your optic nerve when they dilate your. There can be a surrounding halo of yellow tissue bordered by a ring which is known as the double-ring sign. Crucial to vision, the left, The orbicularis oculi muscle is one of the two major components that form the core of the eyelid, the other being the tarsal plate. Normally, there is a small crater-like depression seen at the front of the optic nerve head. Temporal arteritis is less common but involves characteristic symptoms. Last reviewed: July 22, 2022 This is a highly fenestrated (roughly 200 300 holes) area that allows passage of the optic nerve axons into the extraocular space. 2016 Apr;100(4):505-9. doi: 10.1136/bjophthalmol-2015-307043. Colobomas affecting the optic nerve often result in low vision. the visual cortex) within the calcarine sulcus. According to studies, about 5% of people with glioma will develop blindness.10. It therefore has a relative mixture of both glial and connective tissues, and is referred to as a transitional zone. Optic nerve sheath meningiomas (ONSM) are rare benign tumors of the central nervous system. The https:// ensures that you are connecting to the Visual acuity decreases to the point where the patient can only perceive hand motion within a few hours. 8.8). Treatment: total abstinence from alcohol and smoking is indicated, as is a balanced diet high in protein. Cranial arteritis (sometimes called temporal arteritis) Multiple sclerosis. 6.8a and b Optic disc drusen.a Ill-defined, large, bright, white drusen deposits. 2020 Oct 7;11(1):53-56. doi: 10.4103/tjo.tjo_44_20. Current research estimates the prevalence of optic nerve drusen at about 0.5 to 2.4%.9 Unfortunately, there is no treatment for optic nerve drusen. This can cause visual abnormalities in both eyes. It is made up of about 1 million small individual thread-like nerve fibers that come from the retina. Each eye consists of one optic nerve. MRI scan shows diffusely enlarged optic nerve, chiasm . As the artery emerges at the apex of the orbit, it produces a triplicate of posterior ciliary arteries, along with the central retinal artery. Kim Bengochea, Regis University, Denver. Low vision cant be corrected by contact lenses or eyeglasses. Chronic arterial hypertension, especially with high diastolic values, can result in bilateral optic disc edema with significant prominence. Women can be carriers. Some of these conditions have no cure, but early diagnosis is important. For more information about the optic nerve, take a look at the videos, articles, quizzes andillustrations included in the following study unit: The roughly one million nerve fibers that form CN II can be categorized into five groups: There are subtle differences in the histological architecture of the optic nerve along its course. Vincent Ayaga is a medical researcher and experienced content writer with a bachelor's degree in Medical Microbiology. A cecocentral scotoma is present. Vitamins Bl, B12, and B6 and zinc chelates can delay progression of the disease. The nerve exists as a bundle of about 1.2 million nerve fibers made up of retinal ganglion cells (RGCs) and glial cells. doi: 10.1212/WNL.0000000000012226. The latter vascular structure is inconsistent, however, it can be found in the sub-scleral space surrounding the optic nerve at the neuro-ocular junction. It is referred to as atrophy of the optic nerve. Histologically, the distinguishing feature between the connective tissue and glial tissue is the diameter of the fibers. If this protrusion of the optic disc is pronounced and exceeds three diopters or one millimeter, it is then referred to as papilledema. The aim of this study was to determine if optic disc appearance at presentation predicts visual outcome in patients with IIH. It occurs when large quantities of alcohol are consumed in conjunction with an excess of tobacco over a prolonged period (at least several months). While underlying disorders such as vasculitis, embolic phenomenon, or a thrombotic event may cause AION, the likelihood of advanced atherosclerosis as the cause of vascular occlusion should not be ignored. Optic Disc Hypoplasia. The nerve fibers make a sharp 90 degrees turn to pierce the lamina cribrosa. The pictures below illustrate the appearance of the optic nerve as seen by your ophthalmologist. Especially in more severe hyperopia, the optic disc can appear reddish and prominent. Course and Predictors of Visual Outcome of Idiopathic Intracranial Hypertension. There is progressive increase in the diameter of the nerve, with the intraocular component being smaller than the extraocular part. Drusen are often present in both eyes (bilateral), but sometimes occur in only one eye (unilateral). There are also very important vascular structures that are closely related to the intracranial optic nerve: The pia mater is the only meningeal layer covering the intracranial optic nerve. When light hits the retina, the photoreceptors (light-sensitive cells) receive and transmit this information to other specialized cells, including the final cell type in the chain, called the . Fig. With these findings, visual acuity, visual field, and function of the visual system are normal. The onset of this optic neuropathy is insidious, and it gradually leads to irreversible visual field defects and diminished visual acuity. For this reason, the condition only affects one eye at a time. Br J Ophthalmol. Subsequently, the transportation of intracellular contents through the neuron will be disrupted; resulting in swelling of the disc. 6.9a-c Optic disc of a 50-year-old man with arteriosclerotic anterior ischemic optic neuropathy (AION).a Ill-defined and hyperemic with elevation measuring 2 diopters.c Fluorescein angiography demonstrating irregular hyperfluorescence. Vasseneix C, Najjar RP, Xu X, Tang Z, Loo JL, Singhal S, Tow S, Milea L, Ting DSW, Liu Y, Wong TY, Newman NJ, Biousse V, Milea D; BONSAI Group. It has a variable length ranging between 4 10 mm. Therefore, the pupillary light reflex pathway has one afferent limb arising from the ipsilateral optic tract, and two efferent limbs that provide bilateral innervation to the Edinger-Westphal nuclei. Centrally, it attaches the pia mater to the perivascular fibrous sheaths. Last medically reviewed on January 21, 2018. Eyes with glaucoma/glaucoma suspicion, macular/optic nerve edema, pseudophakia, and with . Damage along the optic nerve pathway causes specific patterns of vision loss. Zone alpha is a hypo and hyper-pigmented area of RPE irregularity. 6.2 Pale, mushroom-shaped chronic papilledema in a patient with a brain tumor that went undetected for months. It may be either retrobulbar neuritis (where the optic disc appearance is unaltered) or papillitis (where there is swelling of optic disc). Both optic discs are pale with a reddish shimmer and ill-defined margins. Arterial blood pressure is normal, except for occasional sixth nerve palsy, neurologic symptoms are absent, and there is no evidence of a cerebral mass. They extend into the macula, often in association with retinal folds. Assessment of optic nerve appearance and functions is a daily routine in neuro-ophthalmology. Before Three-Layered Optic Disc Hemorrhages in Idiopathic Intracranial Hypertension. The mitochondrial transmission of the mutation causing the disorder entails a certain probability that the maternal ovum contains and can pass on normal mitochondria in addition to mutated mitochondria. Glaucoma is a set of diseases that can cause vision loss due to optic nerve damage. I would honestly say that Kenhub cut my study time in half. The posterior ciliary arteries supply the orbital part of CN II via the pial vessels, which access the nerve via fibrous septae. Like the preceding intraorbital part, the intracanalicular part is also enclosed by the meninges described earlier. Published by BMJ. Quigley HAAddicks Figure 2: Color fundus photo of the right eye, centered over the optic nerve head. Without fluorescein injection, they exhibit a luminous, yellow appearance in blue light. As more cells are added to the luminal surface of the stalk, the hyaloid arteries regress. Often the fellow eye will develop the disorder with identical symptoms within a few weeks or months.

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