OPTIC NERVE

From Big Medical Encyclopedia

OPTIC NERVE [nervus opticus (PNA, BNA), fasciculus opticus (JNA)] — the second pair of cranial nerves representing initial department of the carrying-out visual way. 3. the N is formed by axons of visual and ganglionic neurocytes (neurocytus opticoganglionaris, LNH) a ganglionic layer of a retina of an eyeglobe. As a part of 3. N are found also efferent fibers which beginning is definitely not established. On development 3. the N as well as the retina, is a part of a brain, than differs from other cranial nerves.

An embryogenesis

germs of the person already on the 3rd week of pre-natal development in a wall of a medullary plate of head department have eye grooves which go deep and form the eye bubbles representing further spherical cambers of lateral walls of a front brain bubble. At the beginning of the 5th week a distal part of eye bubbles is involved inside and eye bowls (eyecups) are formed. At the same time there is a differentiation of walls of eyecups: the periblast turns in pigmental, and internal after complex changes is differentiated in a retina. The emboly leading to formation of an eyecup happens excentricly — slightly closer to its ventral edge therefore the integrity of an eyecup is broken and the so-called vascular crack (fissura chorioidea) is formed. It proceeds in the form of a fillet along a ventral surface of the eye pedicle connecting an eyecup to a brain bubble and forming further 3. N. Along this fillet in a pedicle the eye artery sends through a vascular crack in an eyecup a branch, to-ruyu call an artery of a vitreous (a. hyaloidea). Proximal part of this artery branches in a retina and receives further the name of the central artery of a retina (a. centralis retinae), its distal part is exposed later to involution. Thanks to existence of an artery of a vitreous and the related connecting fabric the fillet in an eye pedicle remains open even after closing of a vascular crack of an eyecup. At the end of the 6th — the beginning of the 7th week the double-walled epithelial tube is formed of an eye pedicle, inside a cut vessels lie. Along with it axons of visual and ganglionic neurocytes of a retina grow along a marginal layer and approach the vessels lying in this tube. Thus, an increasing number of nerve fibrils gets into an eye pedicle. By 8th month of pre-natal development of fiber of intracranial part 3. N become covered by a myelin cover, all nerve gets a well-marked connective tissue cover, and initial fabric of an eye pedicle disappears, except for some gliapodobny elements.

Anatomy

Fig. 1. Optic nerves and visual tracts on a lower surface of a brain: 1 - eyeglobe; 2 — an optic nerve; 3 — an olfactory path; 4 — visual decussation; 5 — a visual tract; 6 — legs of a brain; 7 — papillary bodies; 8 — a hypophysis.

3. the N begins in the field of a visual part of a retina (pars optica retinae) a disk, or a nipple, 3. N (discus n. optici), leaves an eyeglobe through a trellised plate of a sclera [lamina cribrosa sclerae (BNA)], goes back and medially in an eye-socket, then passes through the bone visual channel (canalis opticus) in a head cavity; in the visual channel it is located from above and medially from an eye artery (a. ophthalmica). After escaping of the visual channel on the basis of a brain both 3. N form incomplete visual decussation (chiasma opticum — fig. 1) and pass into visual tracts (tractus optici). Thus, nerve fibrils 3. N continuously proceed to a lateral cranked body (corpus geniculatum lat.). In this regard in 3. N distinguish four departments: 1) intraocular, or intrabulbarny (from the beginning 3. N to his exit from an eyeglobe); 2) orbital, or retrobulbar (from the place of escaping of an eyeglobe to an entrance to an opening of the visual channel); 3) intra channel (corresponding to length of the visual channel); 4) intracranial (from the place of escaping of the visual channel to a hiazma — visual decussation of the right and left intracranial parts 3. N). According to E. Zh. Trona (1955), total length 3. the N makes 35 — 55 mm. Length of intraocular department is 0,5 — 1,5 mm, orbital — 25 — 35 mm, intra channel — 5 — 8 mm and intracranial — 4 — 17 mm.

Fig. 4. Scheme of blood supply of an optic nerve: 1 — a retina; 2 — a choroid; 3 — a sclera; 4 — a back short ciliary artery; 5 — a firm meninx of an optic nerve; in — a soft meninx of an optic nerve; 7 — a visual opening; 8 — an eye artery; 9 — arteries of a soft meninx of an optic nerve; 10 — the central artery of a retina; 11 — a branch of the central artery of a retina to a trunk of an optic nerve; 12 — a vascular circle of an optic nerve; 13 — the lower temporal arteriole of a retina; 14 — an upper temporal arteriole of a retina.

Disk 3. the N represents the conjunction of optical fibers of a retina in the channel formed by covers of an eyeglobe. It is located in a nasal part of an eyeground at distance of 2,5 — 3 mm from a back pole of an eye and on 0,5 — 1 mm from it from top to bottom. A form of a disk round or slightly oval, extended in the vertical direction. Diameter it is equal to 1,5 — 1,7 mm. In the center of a disk there is a deepening (excavatio disci), a cut has the form or funnels (a vascular funnel), or (more rare) than a copper (fiziol, excavation). In the field of this deepening there passes in a retina the central artery of a retina (tsvetn. fig. 4) and the vein accompanying it. Area of a disk 3. by N it is deprived of light-sensitive elements and represents physiologically blind spot (see. Field of vision ). In a retina in the field of a disk 3. and. nerve fibrils have no myelin cover. After escaping of an eyeglobe nerve fibrils 3. N get it, become pulpy. Thickness of nerve fibrils 3. N it is various. Along with fine nerve fibrils (to dia. 1 — 1,5 microns) meet also thicker (5 — 10 microns). The axons of visual and ganglionic neurocytes of a retina creating 3. N, are located in it according to certain sites of a retina. So, nerve fibrils from upper parts of a retina are in the upper (dorsal) party 3. N, fibers from lower parts — in lower (ventral), from internal — in internal (medial), and from outside — in the outer (lateral) side 3. N the papillomakulyarny bunch Going from area of a spot (macula lutea) of a retina (axial, or axial, a bunch) consisting of the most fine optical nerve fibrils in the field of a disk 3. the N is located in nizhnelateralny department. In process of removal 3. the N from an eyeglobe this bunch holds more and more central position in a nerve. At an entrance to the visual channel it is located in the center of a nerve and on a section has rounded shape. It keeps this situation in intracranial part 3. N and in visual decussation — a hiazma.

Fig. 1. A microscopic picture of a normal optic nerve (and — cross — longitudinal sections): 1 — 3 — a meninx of an optic nerve (1 — firm, 2 — web, 3 — soft); 4 — a subdural space; 5 — a subarachnoid space; 6 — the bunches of visual nerve fibrils separated from each other by the partitions departing from a soft meninx of a nerve; 7 — the central vein of a retina; 8 — the central artery of a retina; 9 — a retina; 10 — a choroid; 11 — a sclera; 12 — physiological excavation of an optic disk; 13 — a trellised plate.

3. the N in an eye-socket, the visual channel and a head cavity lies in outside and internal vaginas 3. N, but corresponding to the structure to covers of a brain (vaginae ext. et int. n. optici). The outside vagina corresponds to a firm cover of a brain (tsvetn. fig. 1). The internal vagina limits intervulval space from within and consists of two covers: web and soft. The soft cover directly dresses a trunk 3. N, separating from it only a layer of a neuroglia. The numerous connective tissue partitions (septum) dividing 3 depart from it in a trunk. N on separate bunches of nerve fibrils. Intervulval space 3. the N is continuation of the intershell (subdural) space of a brain and is filled with cerebrospinal liquid. Disturbance of outflow of liquid from it leads to hypostasis of a disk 3. N — to a congestive nipple (see).

At distance of 7 — 15 mm from an eyeglobe in 3. the N, most often from his lower party, enters the central artery of a retina, passes edges in it accompanied by a vein and in the field of a disk 3. the N is divided into branches, krovosnabzhayushchy a retina. At the place of an exit 3. N from an eyeglobe back short ciliary arteries (aa. ciliares post, breves) form in a sclera an arterial texture — a vascular circle 3. N (circulus vasculosus n. optici), or an arterial circle of Galler — the Wood reed, for the account to-rogo is carried out blood supply of adjacent part 3. N. Other part of orbital department 3. the N krovosnabzhatsya, according to Hare (S. Hayreh, 1963, 1969), Vulffa (E. Wolff, 1948), branches of the central artery of the retina passing in it, and according to François (J. Francois with sotr., 1954, 1956, 1963), in a third of cases there is a special axial artery 3. N. Intracranial department 3. N krovosnabzhat branches of a lobby brain (a. cerebri ant.), lobby connecting (. communicans ant.), eye (. ophthalmica) and internal sleepy (. carotis int.) arteries. Outflow of a venous blood is carried out in eye veins (vv. ophthalmicae) and cavernous sine of a firm cover of a brain.

Physiology

3. the N is a yarn (axons) of the third neuron of a visual afferent way; the first neuron — phototouch cells; the second — bipolar neurocytes of a retina (see. Visual centers, ways ). He receives incentives from more peripheral structures of a retina of an eye excited by light in the form of slow tonic potentials which are transformed in a ganglionic layer retinas (see) in the bystry electric impulses transferring the arriving visual information to the visual centers for separate fibers 3. N. Studying of the bioelectric processes which are made in 3. the N, is important for understanding fiziol, bases of a number of visual functions: photoperceptions (see) and color sensations (see. Color sight ), visual acuities (see), etc. Reaction 3. the N on a light incentive consists of a series of the separate fast changings of potential registered on an oscilloscope in the form of so-called spayk. Duration commissure apprx. 0,15 ms, its amplitude and a form for this nerve fibril are constant, i.e. follow the law « Everything or nothing » (see). Change of intensity of light leads only to change of frequency of spayk; amplitude and a form remain invariable. Than intensity of light, that the high frequency of spayk is more. X. Hartlayn showed that in 3. N of vertebrata are available three types of various fibers: the first type reacts explosion of pulse activity to inclusion of light (on-fiber), the second reacts such explosions both to inclusion, and to switching off of light (on-off-fiber) and the third — reacts a superactivity to switching off of light (off-fiber). According to experimental data of Wagner (G. N of Wagner), etc. (1963), received on the fishes having color sight, separate visual and ganglionic neurocytes of a ganglionic layer of a retina and, therefore, separate nerve fibrils 3. N differently answer different color incentives. So, short-wave beams cause pulse activity during photoirritation, and the maximum activity is observed at action of green beams (that corresponds to the maximum spectral response of an eye). Long-wave beams, on the contrary, stop pulse activity, even spontaneous.

One of important features in reactions of fibers 3. the N is the fact that they sum up activity and interaction of more peripheral structures of a visual way. Kafler (S. W. Kuffler, 1952) established that one visual and ganglionic neurocyte (and, therefore, one fiber 3. N) transfers on the axon impulses from many receptor cells disseminated through wide area of a retina, the so-called receptive field; it is caused by existence of extensive horizontal bonds between separate nervous elements in various layers of a retina. Such transfer is caused anatomically as number of separate nerve fibrils in 3. N to 1 million, and number of receptors in a retina apprx. 130 million. The size of receptive fields is various. At mammals receptive fields of optiko-ganglionic neurocytes have the round form, they react strengthening of an impulsation at stimulation of either their center, or the periphery. The relations between the center and the periphery reciprocal (see. Retsiproknost ). In the conditions of dark adaptation receptive fields usually do not find such retsiproknost. Some receptive fields are especially sensitive to the movement of incentives on a retina.

Methods of a research

At a research 3. N define the central sight (see. Visual acuity ), peripheral field of vision (see), visual adaptation (see. visual adaptation ), fields of vision on white, green, blue, red colors (see. Color sight ), carry out skotometriya (see), an oftalmoskopiya (see. Eyeground , Oftalmoskopiya ). Ability 3. N to reproduce the frequency of discontinuous current, the Crimea irritate an eye (the flashing phosphene), gives the chance to determine the speed of emergence and course of excitement in visual neuron (see. Elektroretinografiya ). Besides, state 3. the N is normal and in the conditions of pathology help to specify methods of fluorescent angiography (see) and rentgenol, research of the visual channel.

Fig. 2. The diagrammatic representation of position of the head at a X-ray analysis of the visual channel (and — sideways — from above): 1 — the horizontal plane; 2 — the basal line; 3 — the central beam; 4 — the cartridge; 5 — the sagittal plane.

X-ray inspection of the visual channel. The main technique of a research is the X-ray analysis of a skull in a slanting aim projection, at a cut the central bunch of radiation is combined with an axis of the channel, the located normally to the surface x-ray film. For the first time this way applied in 1910. To Rhese, and then in a little changed look H. A. Golwin in this connection this way often bears a name of both authors. There are various modifications of ways of Gripes of H. A. Golwin. The X-ray analysis of both eye-sockets is necessary for comparison of the right and left visual channels. At the same time the cartridge have the sizes of 13 X 18 cm cross and raise over the plane of a table at an angle 10 ° (fig. 2). The patient is located so that the cartridge adjoined to the studied eye-socket, and the nose bridge was 3 — 4 cm above the average longitudinal line of the cartridge, the vertical diameter of an eye-socket is combined with the average cross line of the cartridge. The line passing from an outside acoustical opening to a corner of an eye-socket (the basal line) forms with a perpendicular to the horizontal plane a corner 40 °, and the sagittal plane of a skull with the same perpendicular — a corner 45 °. The central bunch of radiation is directed to the center of the cartridge perpendicularly to the horizontal plane.

Fig. 3. Roentgenograms and schemes of the left visual channel corresponding to them according to Reza (a) and across Golvin: 1 — the visual channel; 2 — a contour of an orbit; 3 — an upper orbital crack.

The visual channel is normal displayed on a film in the form of a round or oval opening to dia. 3 — the mm (fig. 3), a form and its size depend on projective conditions and focal length. In 33% of cases discrepancy of sizes of both visual channels is observed. The roentgenogram does not give the absolute sizes of diameters of visual channels.

Pathology

Frequency of diseases 3. the N among other eye diseases averages 1 — 1,5%. Weight of diseases 3. the N is defined by the fact that they in 19 — 26% of cases come to an end with a blindness.

Patol, processes 3. the N can be divided into anomalies of development of a disk 3. item; damages; circulator disturbances in system of blood supply 3. N; inflammations; congestive nipple; atrophies (primary and secondary); tumors. Features of defeat 3. N at diseases of a nervous system — see. Sight .

Anomalies of development optic disk are caused by deviations in the course of embryonic development of a rudiment 3. N also meet rather seldom. The following forms concern to them. Megalopapilla — increase in diameter of a disk in comparison with its normal sizes. A hypoplasia — reduction of diameter of a disk. Coloboma (see) — defect, on site to-rogo is formed connecting or glial fabric, both covers, and the nerve taking only covers of a nerve or a nerve or at the same time. At an oftalmoskopiya — on site a disk 3. N the round or oval deepening several times exceeding its sizes. Double disk 3. N (it is connected with inborn splitting of a trunk 3. N); at the same time on an eyeground two disks are visible. Pigmentation of a disk 3. N; on an eyeground gnezdny accumulations of a dark pigment at the place of an exit of vessels or the dark pigment takes all disk. Myelin fibers of a disk 3. and. (normal the myelin cover is formed on sites 3. N after his escaping of an eyeglobe); on an eyeground — deckle-edged white brilliant spots, coming from regional parts of a disk and the retinas passing to surrounding departments. Inborn false neuritis, usually bilateral — on an eyeground the picture reminding neuritis of a disk 3. N; inborn false neuritis is connected with overdevelopment of a glia; he meets at persons with a high hypermetropia more often (see. Far-sightedness ). To differentiate it with true neuritis of a disk 3. the N is helped by lack of dynamics with an oftalmoskopichesky picture of inborn false neuritis. Inborn and hereditary atrophies 3. N are marked out at some forms of dysostoses of bones of a skull (see. Dysostosis ) or result from the infectious diseases postponed vnutriutrobno. A number of anomalies is caused by availability of embryonal fabrics of a rudiment 3. N, not undergone involution: a connective tissue film on a disk 3. N (the rest of connecting fabric on the course of an embryonal artery of a vitreous in the form of the film covering a disk and vessels); gray tyazh, going from a disk 3. N to one of the central vessels of a retina and further forward in a vitreous (the remains of an embryonal artery of a vitreous). Anomalies of development of a disk 3. N are quite often combined with other anomalies of development of an eye; as a rule, they are followed by incurable decrease in sight of various degrees. Their characteristic feature is stationarity of process; any dynamics in a condition of an eye and an oftalmoskopichesky picture at anomalies is always absent.

Damages optic nerve most often arise at the cherepnomozgovy injury which is followed by cracks and fractures of bones of a base of skull with their distribution on walls of channel 3. N, in some cases — only in the field of walls of the channel. Disturbances of an integrity 3. N are one - and bilateral at wounds of temporal area. Reason of a direct injury 3. N are hemorrhages in the intervulval spaces surrounding a nerve and in a nerve with its infringement in the field of the visual channel.

Clinically damage 3. the N is shown by falloff of sight or a blindness with lack of forward reaction of a pupil on light. Directly after injury of a nerve the eyeground is normal; primary atrophy of a disk develops in 7 — 10 days. Approximately in Ve of cases of injuries 3. N on roentgenograms of eye-sockets come to light cracks of walls of channel 3. N.

Neurosurgical treatment at an injury 3. the N in the field of his channel comes down to a decompression of a wall of the channel for the purpose of release of a nerve from a prelum. At the same time make a craniotrypesis with audit of optokhiazmalny area. Operation of a decompression of walls of the channel is recommended to perform in the first 10 days after damage 3. N. At penetration into a cavity of an eye-socket of the damaging body (a stick, a ski, a knife, a pencil etc.) anguishes, gaps and separations 3 are observed. N. At a vyryvaniye 3. the N from his scleral ring in the direction back — an evulsiya (evulsio of the item optici) — suddenly develops a blindness with lack of forward reaction of a pupil on light. At an oftalmoskopiya on site of a disk the defect of fabric surrounded with hemorrhages is defined, vessels at edge of defect break. The retina with its vessels is torn off at edge of a disk. Further vessels of a retina absolutely disappear. Eventually hemorrhages on an eyeground resolve, and defect is replaced with connecting fabric (see. Eyeground ). Treatment — extraction of a foreign body with the subsequent symptomatic therapy.

The separation 3 can meet. N behind an eyeglobe with preservation of a disk — avulsion (avulsio n. optici). If the nerve is broken off ahead of the place of an entrance to it of the central artery of a retina (within 10 — 12 mm from an eyeglobe), oftalmoskopichesk sharp ischemia of a retina and a disk, a considerable arteriostenosis comes to light; sight sharply falls. If gap 3. the N occurs above an entrance to it of the central artery of a retina, suddenly there is a blindness without visible oftalmoskopichesky changes and in 2 — 3 weeks the descending atrophy 3 develops. N.

Circulator disturbances optic nerve (synonym: ischemic hypostasis, ischemic neyrooptikopatiya, vascular pseudo-papillitis, apoplectic nipple, optikomalyation). The reasons leading to circulator frustration 3. N — disturbances of blood supply 3. the N caused by atherosclerosis, temporal giant-cell arteritis (Horton's syndrome — Magata — Brown), a diabetic atheromatosis, an occlusal endarteritis, a nodular periarteritis, arthroses of cervical department of a backbone, etc. Structural changes 3. N at elderly people can develop also as a result of involutional frustration of a hemodynamics.

Clinically at patients at the age of 50 years is also more senior after prodrokhmalny passing mistings suddenly sharply sight in one eye, sometimes before photoperception falls. At a research of a field of vision central are defined scotomas (see), sector losses — lower, are more rare upper hemianopsia (see).

On an eyeground the disk of pale milk coloring, edematous, is noted its small vystoyaniye with hemorrhages in the field of a disk. Hypostasis of a disk develops in 1 — 2 days after emergence of visual disturbances. Very quickly hypostasis of a disk passes into its atrophy with a clear boundary. Permanent decrease in sight of various degree develops, up to a blindness. Through a nek-swarm time can ache and other eye with the same bad outcome.

Treatment — vasodilators, heparin intravenously, intramusculary and under a conjunctiva; in the second eye apply corticosteroids to the prevention of the same process.

Inflammations of an optic nerve subdivide into neuritis intrabulbarny (neuritis of a disk 3. N, or papillitis) and retrobulbar (perineuritis, intersticial neuritis, axial neuritis).

Intrabulbarny neuritis (neuritis of a disk 3. the N, or a papillitis) arises at inflammatory processes in a cornea, an iris, a ciliary body, a choroid and a retina (the chorioretinal centers, retinal periphlebites), injuries of an eye. Main symptoms: various extent of decrease in the central sight, restriction of peripheral sight, disturbance of color sensation, dark adaptation. Intrabulbarny neuritis can arise sharply or gradually. The current can be short and longer. Functions of sight a nek-swarm time can not change or there are passing deteriorations. Reaction of a pupil to light is weakened; changes of reaction of a pupil to light proceed parallel to decrease in visual acuity. Oftalmoskopichesky picture (tsvetn. fig. 6): disk 3. the N is hyperemic, there is small degree his vystoyaniye — to 2,0 dptr (about 0,6 mm); seldom or never — a vystoyaniye in 5,0 — 6,0 dptr (1,5 — 1,8 mm), connected with severe hypostasis of a disk. Edges of a disk hollow pass into an edematous peripapillary retina. Arteries are not changed or narrowed, veins are expanded. A vascular funnel or fiziol, excavation on a disk are covered with exudate. In prepapillyarny area the opacity of the vitreous body is possible.

Treatment of neuritis of a disk 3. N shall come down to the antibacterial and desensibilizing therapy directed to elimination of a basic disease, to use of corticosteroids (orally, retrobulbar osmotherapy, desintoxication, vitamin, to an oxygen therapy, hemotransfusions, use of antispasmodics etc.

In case of timely treatment and a favorable outcome there occurs gradual improvement of sight. At a failure the full or partial atrophy 3 develops. N with falloff of sight, sometimes to a blindness.

Retrobulbar neuritis. Inflammatory process is localized on site 3. N between an eyeglobe and hiazmy, without extending to a disk, on an eyeground of change come to light not always. Retrobulbar neuritis subdivides on: 1) inflammation only covers 3. N — a perineuritis which develops for the second time, on continuation (per continuitatem); 2) an inflammation of peripheral fibers of a trunk of a nerve — intersticial neuritis; at the same time inflammatory process begins usually in a soft cover 3. the N and on connective tissue partitions (septa) passes to peripheral nerve fiber layers; 3) inflammation of a papillomakulyarny (axial) yarn 3. N — axial neuritis.

Etiology of retrobulbar neuritis: inflammatory processes in an eye, an orbit, paranasal sinuses, neuroinfections, multiple sclerosis, an optokhiazmalny arachnoiditis, meningitis of various etiology, systemic infections (flu, quinsy, malaria, a sapropyra, syphilis, oral sepsis); retrobulbar neuritis also exchange disturbances, patol, pregnancy, hron can be the cornerstone, of intoxication lead, tobacco, alcohol, quinine.

Changes of fields of vision at retrobulbar neuritis are various depending on a form: at a perineuritis it can not be noted any visual disturbances; at intersticial neuritis these disturbances come down to the wrong concentric restriction of a field of vision; the central scotoma, absolute or relative is characteristic of axial neuritis (on green or on red color). Retrobulbar neuritis affects both eyes more often though between defeats of one and others 3. the N is observed a gap in time. Distinguish acute and hron, forms retrobulbar neuritis. At an acute form for several hours sight can sometimes go down to zero; at chronic — falling of sight happens slowly, for one or several weeks. Retrobulbar neuritis always comes to light disorders of color sight (in the earliest stages — reduction of the threshold of a chromatics), the decrease in dark adaptation unequal in different sites of a mesh cover. Oftalmoskopicheski can sometimes come to light a picture of neuritis of a disk 3. N.

Treatment of retrobulbar neuritis same, as intrabulbarny (see above).

The outcome of retrobulbar neuritis at timely treatment quite often can be favorable — visual functions are recovered. In hard cases process comes to an end with an atrophy 3. N that is shown by decrease in visual acuity and restrictions of a field of vision, hl. obr. in the form of the central scotoma; sometimes there comes the blindness. Retrobulbar neuritis with hypostasis of a disk 3. N in the predictive relation are less favorable in comparison with cases when changes on a disk are absent.

Neuropathy of an optic nerve — the damage of an optic nerve which is observed at some patients having a hypertension, inflammatory diseases of kidneys, pathological pregnancy, etc. At a neuropathy of an optic nerve its disk can be a little increased in sizes, fabric it is slightly edematous and dimmy, with light pink color and a yellowish shade. Borders of a disk indistinct. Arteries are most often narrowed, and veins are expanded (tsvetn. fig. 7). During the involvement in process of a peripapillary retina there is a neuroretinopathy.

Congestive nipple — hypostasis of a disk 3. N without the phenomena of an inflammation or with very small manifestations of the secondary inflammation developing because of stagnation (see. Congestive nipple, optic nerve ).

Atrophy of an optic nerve can be primary (simple) or secondary. Primary atrophy of a disk 3. the N is formed at a prelum 3. N on any site the tumors, granulomas sclerosed by vessels of the basis of a brain at basal meningitis. Extremely seldom atrophy of a disk 3. the N results from primary defeat of visual and ganglionic neurocytes of a ganglionic layer of a retina — so-called retinal ascending: atrophy 3. N. Secondary atrophies develop after hypostasis of a disk 3. N or neuritis 3. N, at optokhiazmalny arachnoiditis (see).

At an atrophy 3. N, both primary, and secondary, functions of sight are sharply broken, sometimes sight sharply decreases to photoperception, Dark adaptation worsens, the color sensation suffers. Extent of disturbance varies over a wide range and depends on localization and intensity of process. At defeats of a papillomakulyarny bunch considerable decrease in visual acuity is noted. At defeat of the nerve fibrils going from the periphery of a retina and at safety of a papillomakulyarny bunch visual acuity can be satisfactory. Change of a field of vision depends on localization and prevalence of atrophic process.

Oftalmoskopicheski (tsvetn. fig. 8) at primary atrophy of border of a disk accurate, color its white or grayish-white, bluish or slightly greenish. Blanching can take all disk or only its temporal part. At a secondary atrophy 3. N (tsvetn. fig. 10) of border of a disk indistinct, washed away, color its gray or dirty-gray, a vascular funnel or fiziol, excavation is filled with connecting or glial fabric, the trellised plate of a sclera is not visible. Blanching of a disk 3. the N at an atrophy depends on a zapustevaniye of the vessels feeding a disk from development in 3. N of glial and connecting fabric and death of a considerable part of nerve fibrils. The retinal ascending atrophy of a disk 3. the N differs from other forms of an atrophy in his yellow wax coloring. Arteries and veins at an atrophy 3. N, both primary, and secondary, are narrowed. Reduction of number of small vessels on a disk 3 is noted. N (Kestenbaum's symptom). At glaucoma it is as a result long the existing increased intraocular pressure there comes the atrophy of fibers 3. N with characteristic excavation of his disk (tsvetn. fig. 9).

At the choice of a method of treatment of an atrophy 3. the N should consider etiol, a factor. Antispasmodics, vitamin therapy (especially vitamins of a complex B), drugs of iodine (are shown vasodilating, at an atrophy because of a sclerosis); at an atrophy owing to an optokhiazmalny arachnoiditis treatment antiinflammatory, operational (an adhesiotomy and the cysts squeezing 3. N). From physiotherapeutic actions at atrophies of any etiology ultrasound in pulsed operation on an open eye, an endo-nasal medicinal electrophoresis is shown (vasodilators); at an atrophy owing to an optokhiazmalny arachnoiditis — an endo-nasal medicinal electrophoresis (papain).

Tumors of an optic nerve in overwhelming number of cases happen primary, high-quality, develop from a glia of a nerve or its covers. Secondary tumors 3. the N is quite often malignant, sprout a nerve from the next fabrics or are metastasises. From primary tumors gliomas in most cases meet, meningiomas and extremely seldom are more rare than a neurofibroma. Gliomas 3. N occur usually at children up to 10 years and is rare at adults. Clinically these tumors irrespective of them gistol, structures proceed the same: are followed by the progressing exophthalmos (fig. 4, a), development of a congestive nipple and depression of function of sight. Gliomas 3. N share on orbital and intracranial, they can arise throughout a nerve and via the visual channel to burgeon in a head cavity, to extend to visual decussation, a bottom of the third cerebral cavity and 3. N of the second eye.

Fig. 4. Some clinical and radiological manifestations of a glioma of the left optic nerve at the child of 6 years: and — an exophthalmos of the left eyeglobe; — expansion of an opening of the channel of the left optic nerve (it is specified by an arrow) on the roentgenogram according to Reza, in the left drawing — norm for comparison; in — a direct venogramma of eye-sockets: the left eye-socket — an upper orbital vein (1) is displaced up, the large additional branch of the lower orbital vein (2) borders a tumor; the right eye-socket — the normal course of veins.
Fig. 5. Diagrammatic representation of some stages of operation of a kranioorbitalny oncotomy of the right optic nerve: and — from subfrontal access the bottom of a front cranial pole, an orbital part of a frontal bone and area of visual decussation are naked; — an orbital part of a frontal bone is opened, the affected optic nerve at visual decussation with the subsequent oncotomy is cut; in — plastics of an orbital part of a frontal bone a perforated plate from quickly hardening plastic; 1 — visual decussation, 2 — the left optic nerve, 3 — a front cranial pole, 4 — eyeballs, 5 — a tumor of the right optic nerve, 6 — the muscle raising an upper eyelid, 7 — the stump of an optic nerve which remained after removal, 8 — a perforated plate from plastic.

Orbital gliomas meet approximately by one and a half times more often than intracranial. Symptomatology of orbital gliomas: a blindness of the affected eye, an exophthalmos — at first forward, then with the shift of an eye, an obstacle to reposition of an eye, restriction of its movements. In an eye-socket the glioma forms the node limited from surrounding fabrics to covers of a nerve which, as a rule, the tumor does not sprout. The expansion of an opening of the visual channel revealed on roentgenograms of eye-sockets is a characteristic symptom of primary tumors 3. N (fig. 4, b) and at the same time objective sign of spread of a tumor to a head cavity. For early diagnosis of primary tumors 3. the N matters a venografiya of an eye-socket (fig. 4, c) and ultrasound examination of eye-sockets (see. Ultrasonic diagnosis ). These methods of a research reveal existence of a tumor in an eye-socket, its size and situation in an early propagation step when there is no expansion of an opening of channel 3 yet. N. Radical removal of tumors 3. N it is possible only at excision of a nerve within healthy fabrics. For this purpose A. I. Arutyunov et al. (1970) developed a method of a single-step kranioorbitalny oncotomy (from an eye-socket and a head cavity, fig. 5). The eyeglobe and its muscular device at this operation remain. It is possible to judge radicalism of an oncotomy only on the basis of data gistol. researches of intracranial department 3. N, in the place of crossing of a nerve to visual decussation.

See also Eye ; Visual centers, ways ; Visual analyzer .


Bibliography: Averbakh M. I. Ophthalmologic sketches, M., 1949; Arutyunov A. I. and d river. About surgical treatment of gliomas of an optic nerve, Vopr, neyrokhir., No. 2, page 8, 1970; Theological A. I. and Zhdanov V. K. Philosophy of a clinical electrophysiology of visual system, Nauch. works Mosk. nauch. - issled, in-that eye diseases, century 22, page 6, 1976; Merkulov I. I. Clinical ophthalmology, book 2, Kharkiv, 1971, bibliogr.; Merkulov I. I., Vinetskaya M. I. and Babich S. B. To biochemistry of an optic nerve, in book: Vopr, neyrooftalm., under the editorship of I. I. Merkulov, t. 9, page 39, Kharkiv, 1962, bibliogr.; Pole B. L. Povrezhdeniya of an organ of sight, L., 1972; Sokolova O. N. and Volynsk Yu. N. Tumors of an optic nerve and hiazma, M., 1975, bibliogr.; Tronas E. Zh. Diseases of a visual way, L., 1968, bibliogr.; Shlykov A. A., Sokolova O. N. and Osipov I. L. About disturbance of visual functions at a craniocereberal injury and indications to neurosurgical treatment, in book: A severe craniocereberal injury, under the editorship of A. I. Arutyunov and N. D. Leybzon, page 192, M., 1969; With about g a n D. G. Neurology of the visual system, Springfield, 1967, bibliogr.; Medical ophthalmology, ed. by F. C. Rose, L., 1976; Neuroophthalmologie, hrsg. v. R. Sachsenweger, Lpz., 1975, Bibliogr.; System of ophthalmology, ed. by S. Duke-Elder, v. 12, L., 1971; Walsh F. B. Clinical neuroophthalmology, Baltimore, 1947.

I. I. Merkulov, O. H. Sokolova; B. A. Vorobyova (An.), V. G. Ginzburg (rents.).

Яндекс.Метрика