CONJUNCTIVA

From Big Medical Encyclopedia

CONJUNCTIVA (tunica conjunctiva; lat. to connect conjugere) — the mucous membrane of an eye covering a back surface a century and a front surface of an eyeglobe up to a cornea.

Anatomy

Fig. 4. An eye with a normal conjunctiva.

Main properties K. — tenderness of structure, light pink color, transparency and humidity of a surface (tsvetn. fig. 4). Distinguish several departments of K. Chast it, edges the century dresses a back surface, is called To. century (conjunctiva palpebrarum); the part covering a sclera — To. eyeglobe or sclera (conjunctiva bulbi s. sclerae), and places of transition with top and bottom a century on an eyeglobe — the top and bottom arch To. (fornix conjunctivae sup. et inf.). The slit-like capillary space limited in front for centuries, and behind to front department of an eyeglobe carries the name of a conjunctival sac. To. the century is subdivided on To. a cartilage (conjunctiva tarsi) and on orbital To. (conjunctiva orbitalis), or a transitional fold, edges covers a back surface of a century from edge of a cartilage to the arch. It is called a fold because here To. at open centuries forms horizontal folds that allows an eyeglobe to keep the mobility. Upper arch deeper, than lower.

To. a cartilage at free edge of a century has a smooth surface, but is already 2 — 3 mm higher (on a lower eyelid — below) free edge the surface becomes slightly rough. At an outside corner of a century (corners of cartilages) the roughness is noticeable with the naked eye, and on other extent it can be found by means of a magnifying glass. The roughness is caused by presence of nipples. Through transparent To. a cartilage normal illuminate in the form of the thin yellowish lines parallel each other, glands of a cartilage a century (a meybomiyeva of gland). To. an eyeglobe it is very gentle, differs in smoothness, transparency, it is appeared through by white coloring of a sclera. Only at a limb To. it is closely soldered to the subject fabrics. Rykhlo connected to an eyeglobe To. it is freely displaced and swells at inflammatory processes. At a limb sites of pigmentation are sometimes visible.

In an internal corner of an eye To. participates in formation of the lacrimal meat (caruncula lacrimalis) and semi-lunar fold (plica semilunaris conjunctivae). The lacrimal meat on the structure reminds skin (there is only no a corneous layer), contains small hairs, sebaceous and acinous glands. Several knaruzha from it is the semi-lunar fold formed To. scleras; it represents the rudimental organ corresponding to the third century at animals and consists of a multilayer epithelium and connecting fabric.

Histologically in To. distinguish an epithelial layer (epithelium conjunctivae) and a connective tissue basis — own plate To. (lamina propria conjunctivae).

Fig. 1 — 3. Microdrugs of a conjunctiva (norm): fig. 1 — a conjunctiva of a limb (the arrow specified a multilayer flat epithelium); fig. 2 — a conjunctiva of a transitional fold (shooters specified scyphoid cells in a multilayer cylindrical epithelium); fig. 3 — a conjunctiva of a cartilage a century (the arrow specified a multilayer cylindrical epithelium).

Epithelium To. century multilayer (tsvetn. fig. 1), its surface layer consists of cylindrical cells, deep — of cubic cells; in To., covering cartilages a century, 2 — 4 layers of cells, in a transitional fold — to 5 — 6. In an epithelium there are a lot of mucous (scyphoid) cells allocating mucous contents — mucin. On To. it is more lower eyelid of scyphoid cells, than on an upper eyelid (tsvetn. fig. 2). On To. an eyeglobe the multilayer epithelium changes the character: the surface layer becomes flat, and near a limb of a cornea multilayer flat and without sharp border passes into an epithelium of a cornea. Mucous cells in an epithelium To. the eyeglobe is not enough.

Tarzalny part K. (tsvetn. by fig. 3) it is densely soldered to a cartilage of a century, between them there is rather thin coat of a connective tissue basis. Orbital part K. a century, and also To. an eyeglobe it is connected to the subject fabric a friable and subconjunctival basis (tela subconjunctivalis) that facilitates mobility as To., and eyeglobe.

A connective tissue basis To. the century can be divided into two layers differing on distribution and character of cells and fibers: subepithelial (adenoid) and deep (fibrous). Subepithelial layer To. it is formed generally of the same two basic elements, as a true adenoid tissue — of a setevidny stroma (reticulum), the plasmocytes and lymphocytes sometimes forming small accumulations — follicles. The deep layer is presented by the friable fibrous connecting fabric rather poor in vessels and cellular elements.

Fig. 1. Microdrug of a conjunctiva of the adult: in a subepithelial layer (1) the network of argyrophil fibers is located (reticulum) in which loops abundance of cellular elements (2); in a deep layer a collagenic fibrous stroma (3); impregnation by silver.
Fig. 2. Microdrug of a conjunctiva of the newborn: under a cover epithelium (1) gentle friable connecting fabric (2) with cells and posterior collagenic pyramids; impregnation by silver.
Fig. 3. Microdrug of a conjunctiva of the elderly person: all thickness of a conjunctiva consists generally of rough collagenic bunches; impregnation by silver.

In normal To. the adult the abundance of the low-differentiated cells and histiocytic elements various by the form is noted. In a subepithelial layer there is a network of argyrophil fibers in which loops cells accumulate. Elastic thin fibrils are presented in a small amount (fig. 1).

In the first 2 — 3 months out of uterine development of the person a connective tissue basis To. the century (its own plate) consists of friable connecting fabric and fine collagenic fibers (fig. 2). In it, unlike To. adults, it is found the smaller quantity of cellular elements and big tenderness and friability of an arrangement of fibers of a connective tissue basis is considerable.

Structure of cells of own plate To. newborns also considerably differs from To. adults. Lymphocytes in comparison with other cells meet seldom, hl. obr. in a surface layer, near blood vessels. Plasmocytes absolutely are absent. The ground mass of cells of own plate To. newborns are made by fibroblasts and cambial elements.

The changes observed in To. at elderly people, are characterized by reduction of quantity and change of structure of cellular elements, and also strengthening of process of collagenization that leads to reduction of amount of argyrophil fibers. Together with relative depletion of a subepithelial layer cellular elements the quantity of the low-differentiated forms and lymphocytes decreases. Plasmocytes at which symptoms of dystrophy are often observed become basic elements of infiltration of a subepithelial layer. Collagenic bunches become thicker, rough, often are exposed to a hyalinosis. Subepithelial fabric at elderly people loses adenoid structure (fig. 3).

Glands K. (Krause's glands), located in a top and bottom transitional fold, on a structure and character of a secret are similar to the lacrimal gland. They are totaled from 20 to 30 on an upper eyelid and only 6 — 8 on lower. Mostly they a round or oval form also are in a subepithelial layer. Each gland consists of a number of segments and has the general output channel. The same glands (Valdeyer's gland) are available on border of tarzalny and orbital part K. In a temporal part of the upper arch To. output channels of the lacrimal gland open.

To. it is plentifully supplied with vessels. Back conjunctival vessels, coming from systems of arterial arches of a top and bottom century, and the front conjunctival vessels relating to system of front ciliary arteries participate in its vascularization. Back conjunctival vessels feed To. a cartilage, a transitional fold and an eyeglobe, behind an exception a feather limbal-ache zones, edges it is supplied with front conjunctival vessels. Front and back conjunctival arteries are tied by an anastomosis.

Veins To. accompany arteries, but their branchings are more numerous. Part of them falls into veins of the person, and others — into system of veins of an eye-socket. Limf, vessels To. a century form the dense network lying in subconjunctival fabric. The direction of these vessels matches the course of blood vessels — from a temporal half To. limf, vessels go to a preear node, and from nasal — to submaxillary limf, nodes.

Sensory nerves To. receives from the first branch of a trifacial — an optic nerve (n. ophthalmicus). Its branch — the lacrimal nerve (n. lacrimalis) — innervates temporal part K. upper and partly lower eyelid; the supraorbital nerve (n. supraorbitalis) and a supratrochlear nerve (n. supratrochlearis) supply nasal part K. upper eyelid. — a maxillary nerve (item maxillaris) depart from the second branch of a trifacial a malar nerve (item zygomaticus) which supplies a temporal half To. a lower eyelid, and an infraorbital nerve (n. infraorbitalis) supplying its nasal half.

Physiology

Abundance of a sensitive innervation in To. provides performance of protective function — at hit of the smallest foreign bodys secretion of the lacrimal liquid amplifies, the blink movements therefore the foreign body mechanically is removed from a conjunctival sac become frequent. Secret of conjunctival glands, constantly moistening a surface of an eyeglobe, carries out a role of the lubricant reducing friction at its movements, protecting a cornea from drying and keeping its transparency. Barrier function K. it is carried out thanks to the content in the lacrimal liquid of enzymes (a lysozyme, etc.) and to abundance in submucosal adenoid fabric of lymphoid elements.

Pathology

Symptomatology

Discoloration. A hyperemia To. it is noted at its inflammation (see. Conjunctivitis ), at noninflammatory stagnation of blood; blanching To. — at the general anemia. Pigmentation To. it is noted scleras at various general diseases of an organism: yellow color — at jaundice, yellowy-brown — at an addisonovy disease, flaky-gray — at argyrosis (see).

V K. also hemorrhages — are observed at an injury, an inflammation, at increase in blood pressure etc.

The chemosis (hemoz) comes very often under various conditions: in addition to an inflammation To. or fabrics, adjacent to it, it is observed at stagnation of blood and a lymph in an eye-socket, napr, at tumors of an eye-socket, at exophthalmos (see), and also at anemias, nephrite and so forth. At severe hypostasis To. approaches edges of a cornea in the form of a vitreous shaft.

Emphysema of a conjunctiva arises along with emphysema century (see) at damages of walls of an eye-socket owing to what conditions for occurrence of air under are created To. from surrounding okolonosovy bosoms.

Diseases

the Lymphangiectasia of a conjunctiva — the phenomenon frequent, especially in the area K. scleras; it is characterized by emergence under an epithelium To. roundish watery bubbles size about a pin head which quite often happen multiple and, merging with each other, sometimes form small translucent limf, cysts. Treatment consists in a puncture or removal them.

to Fig. 7. Tuberculosis of a conjunctiva (defeat is shown by shooters

Tuberculosis of a conjunctiva — a rare disease; arises in usually endogenous way as secondary process or owing to distribution from the struck fabrics. Tubercular process strikes more often To. upper eyelid; it is shown usually in the form of an ulcer with the pitted edges and a curdled or grease bottom. At the bottom of an ulcer and in surrounding it To. grayish small knots are visible. Sometimes tuberculosis To. it is shown in the form of papillomatous growths (see tsvetn. fig. 7) in which it is possible to see small knots, characteristic of it. The course of tuberculosis To. chronic with bent to a recurrence. Treatment the general and local (streptomycin, PASK, Ftivazidum, etc.) -

The pempigus of an eye (pemphigus) — a rare disease, a characteristic symptom to-rogo is bulging on To., and also on a cornea and skin a century. The etiology of an eye pempigus is unknown; assume that it a virus origin. Can proceed at the general heavy, hron, a disease of an organism with gradual defeat of all sites of skin and mucous membranes of pemfigusny process. On To. a century and transitional folds bubbles of various size are formed, they quickly burst, and on site them there are flat erosion covered with a fibrinous plaque; limited ulcerations are less often formed. Many ophthalmologists refer to an eye pempigus also essential cicatricial wrinkling To., at Krom already from the very beginning of a disease scars on are noted To. with the wrong growth of separate eyelashes, and increase of process leads to wrinkling To., to symblepharon. Forecast bad: treatment unsuccessfully, a disease always comes to an end with a blindness of both eyes.

Dystrophic processes

concern To them an amyloidosis, a pingvekula, an alate pleva (see. Pterygium ), a xerosis, or dryness, To. (see. Xerophthalmia ), symblepharon, epitarsus.

An amyloidosis of a conjunctiva — a peculiar defeat of not clear etiology. Can be manifestation of the general amyloidosis (see) or a local disease, Krom is often preceded any hron, by an inflammatory disease To., napr, trachoma, or an independent disease of K. Nachinayetsya gradually, without the inflammatory phenomena, as a rule from transitional folds, extending on To. a cartilage, a semi-lunar fold, sometimes taking also tissues of a cartilage. In the beginning the thickening is observed To., then in it there are hilly growths, wax-like, sometimes translucent and slightly jellylike. Further thickenings To. increase, act to the area of a palpebral fissure and the patient hardly can open eyelids. Pathoanatomical the thickening or thinning of an epithelium is noted To., and under it accumulation of the homogeneous masses giving reaction to amyloid or a hyalin, existence of infiltration from plasmocytes. Treatment — operational removal of the part regenerated To.

Pingvekula (fatty tumor) — the small yellow-white education which is slightly towering, rounded or triangular shape, often developing at elderly people under the influence of various long external irritants. Pathoanatomical, in addition to keratinization of an epithelium, the main change is dystrophy (vitreous degeneration) of subepithelial fabric. Pingvekula quickly leaves only for cosmetic reasons.

Symblepharon — a cicatricial union To. centuries with To. eyeglobe. Symblepharon arises after burns, diphtheria of an eye, a pempigus, wounds etc. when on opposite surfaces To. a century and an eyeglobe wound or ulcer surfaces which in the subsequent grow together are formed. Distinguish front and back symblepharon: if the arch To. it is not destroyed — symblepharon front; if the arch does not exist — symblepharon back. The look, special on the origin, represents the back symblepharon which is formed owing to widespread scarring To. at trachoma with smoothing of transitional folds and reduction of all conjunctival sac. Treatment operational: plastic surgeries on K.

Epitarzus — a dublikatura of a mucous membrane of a century between the arch To. and cartilage of an upper eyelid; has an appearance of an overlay of whitish color with the smooth surface penetrated by vessels. Emergence of an epitarsus is caused by incomplete closing of a frontal and maxillary crack (congenital anomaly). Is not subject to treatment.

Tumors

High-quality. Fibromas To., consisting of sosochkopodobny growths of connecting fabric, have a smooth surface, a soft or dense consistence, are capable to rapid growth, especially in the field of the lacrimal meat. Soft fibromas often bleed. Close to them on a structure there are papillomas To., having, unlike fibromas, the pulled surface similar to mulberry berry or a cauliflower. They are more often localized on To. an eyeglobe, it is preferential at a limb from where can extend also to a cornea. Papillomas quite often recur and at a malignancy are subject to operational treatment.

Hemangiomas and lymphangiomas meet as initially arising in To., and extending to it from a century. Hemangiomas (see) more often are located on To. an eyeglobe, have the mesodermal nature and have inborn character. Removal of hemangiomas is dictated in one cases by cosmetic reasons, in others — the disturbances of functions of an eye caused by them or developing of bleedings. Operational removal of a hemangioma with preliminary bandaging, an obkalyvaniye of vessels or cauterization by means of diathermocoagulation is made. Also short-distance roentgenotherapy is applied. Lymphangiomas (see) meet very seldom.

Fig. 5. A dermoid of a conjunctiva of an eyeglobe in the field of a limb (it is specified by an arrow).

Dermoid and lipodermoid — inborn tumors. Dermoids To. clinically represent small formations of rounded shape with a clear boundary, whitish or yellowish color (tsvetn. fig. 5); they are located usually at nizhnenaruzhny edge of a cornea and occupy its periphery a little, are not mobile, a dense consistence. The surface of dermoids is similar to skin: surface layers of an epithelium orogovevat, iod them is dense fibrous connecting fabric and in it hair sacks, grease and sometimes sweat glands. Along with dermoids also other anomalies of development of an eye can meet (colobomas a century, irises, etc.). The arrangement under is characteristic of a lipodermoid To. in the field of the equator of an eye between an upper straight line and an outside straight line muscles in the form of a thick fold To., edges the edge leaves from under a century and kzad it is lost imperceptibly in the depth of an eye-socket. Lipodermoid contains in the thickness more fatty tissue, than a dermoid and therefore has more yellowish color and softer consistence; it is more mobile. Treatment of that and other education — operational removal.

A nevus To. — the pigmented and not pigmented birthmarks (see. Nevus ). Not pigmented spots To. in the form of flat yellowish eminences with a smooth surface most often are located about a limb of a cornea. They can be exposed to a malignancy. In the absence of growth the nevus is not subject to treatment.

Malignant. The epithelioma, or a carcinoma, is more often localized in the field of a limb where To. most often is exposed to external irritations. Pathoanatomical epitheliomas To. in most cases represent planocellular cancer (see) with the chicken skin inclined to superficial ulcerations and papillomatous vegetations of belovatosery or pinkish-yellow color depending on the number of vessels. Elements of an epithelioma, burgeoning in fabric of a cornea and To., have bent to get into an eye-socket, to surround a surface of an eyeglobe, forming peribulbarny epitheliomas. In initial stages the roentgenotherapy is possible; also an operative measure — a careful oncotomy is shown, and at germination in an eye-socket — ekzenteration of an eye-socket (see).

Fig. 6. A melanoma of a conjunctiva of an eyeglobe (it is specified by an arrow).

Melanoma To. meets quite often. It develops from the preexisting pigmental birthmark in the field of a limb, the lacrimal meat or a semi-lunar fold, has an appearance of smooth or hilly tumors of dark color (see tsvetn. fig. 6). Melanoma (see) often gives a recurrence and metastasises, especially after an unsuccessful operative measure. In the earliest stages in the absence of the active growth of a melanoma it is necessary to abstain from an operative measure. At growth of a tumor or in case of a recurrence there can be a need of removal of an eye or even an ekzenteration of an eye-socket.

Cysts have various origin. Inborn meet less than acquired (limf, cysts, at a lymphangiectasia To. and epithelial cysts of retentsionny character — a delay of a secret of conjunctival glands and glands of cartilages a century). Their size from a pin head to a pea. Cysts develop also owing to growth of an epithelium in depth of fabric at inflammations To., and also at an injury owing to output channels, cicatricial for rashcheniye, with formation of cavities in them. V K. also adventitious cysts owing to an invasion in can be formed To. parasites (cysticercus, filarias, etc.).

See also Eyelids , Eye .



Bibliography: Volokonenko A. I. About age changes in a conjunctiva of the person, Vestn, oftalm., t. 14, No. 1, page 19, 1939; Merkulov I. I. Clinical ophthalmology, book 1, page 99, Kharkiv, 1966; The Multivolume guide to eye diseases, under the editorship of V. N. Arkhangelsky, t. 1, page 185, M., 1962, t. 2, book 1, page 46, 1960; System of ophthalmology, ed. by S. Duke-Elder, v. 2, L., 1961, bibliogr.

A. I. Volokonenko.

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