2 English reference conjunctiva [Chinese medicine terminology examination and approval Committee. Terminology of traditional Chinese medicine (20 13)]
Conjunctiva [Landau Chinese-English Dictionary]
Conjunctival coat [Landau Chinese-English dictionary]
Landau Chinese-English dictionary
Conjunctival sac [Landau Chinese-English Dictionary]
3 Overview Conjunctiva refers to a thin translucent mucosa [1] that starts from the eyelid margin and ends at the corneal margin. Covering the back of eyelid and eyeball surface [1]. It is a transparent membrane with multiple layers of columnar epithelium and a small amount of connective tissue. Eyelid conjunctiva is lined on the inner surface of eyelid, and bulbar conjunctiva is attached to the front of eyeball. These two parts are continuous with each other. When the eyelids are closed, the space surrounded by conjunctiva is called "conjunctival sac". It can protect and promote eye movement. The junction of bulbar conjunctiva and palpebral conjunctiva is called fornix conjunctiva. The conjunctiva is rich in blood vessels and nerve endings, and there are a few mucus glands, which can secrete mucus, lubricate the eyeball and reduce the friction between eyelid conjunctiva and cornea. Chlamydia trachomatis mainly invades eyelid conjunctiva and fornix conjunctiva. Acute bacterial conjunctivitis and viral conjunctivitis are both caused by bacteria and viruses infecting the conjunctiva, which are both contagious.
4 Conjunctival anatomy The conjunctiva is a layer of mucosa covering the inner surface of eyelid, which reflects to the surface of bulbar conjunctiva and ends at the limbus corneae. It is connected with the skin at the eyelid margin and the corneal epithelium at the corneal margin, forming a sac called conjunctival sac. The conjunctival sac communicates with the outside world with the palpebral fissure as the opening, connects with lacrimal gland epithelium at the lacrimal punctum, and connects with nasal mucosa through lacrimal passage.
Conjunctiva is divided into:
① eyelid conjunctiva iva: divided into: a. eyelid margin; B. meibomian part; C. Orbit (Figure 8.3.7. 10 1).
② fornix conjunctiva iva: divided into: a. superior fornix; B. Inferior vaults; C. lateral vault; Medial vault.
③ bulbar conjunctiva iva can be divided into: a. sclera; B. limbus corneae.
④ Fold (semilunar fold)
Half-moon): Eyelid conjunctiva is lined on the inner surface of eyelid. Its marginal part extends from the gray line of the palpebral margin to the inferior tarsal sulcus, which is continuous with the skin epithelium, and consists of conjunctival stratified squamous epithelium transitional from the skin epithelium. This part is the prone site of palpebral margin cancer. Submeibomian communication is often the place where foreign bodies remain. The conjunctiva of meibomian is rich in blood vessels, which is closely adhered to meibomian and cannot be fixed. The upper eyelid is more closely adhered than the lower eyelid. Through the conjunctiva of the meibomian part, meibomian glands, such as yellow and white lines, are parallel to each other and arranged perpendicular to the meibomian margin. It is difficult to separate eyelid conjunctiva when doing tarsectomy. From the upper edge of the eyelid plate to the vault is the orbital conjunctiva.
The conjunctiva in the fornix is formed by the mucous membrane on the inner surface of the eyelid, which is thicker and looser than the conjunctiva in other parts, so that the eyeball has enough room for movement and will not hinder the movement of the eyelid. The superior fornix is located between eyelid and eyeball, 8 ~ 10 mm above corneal limbus. The levator palpebrae superioris tendon and superior rectus muscle are closely related to the conjunctiva of the superior fornix, so special attention should be paid to avoid damaging the above muscles and tendons during the operation of the superior fornix. The inferior fornix is located between the lower eyelid and eyeball, 8mm from the lower edge of corneal limbus. The lateral vault is located between the outer canthus and eyeball, with a distance of 14mm from the corneal limbus, and the narrowest part of the medial vault is 7mm from the corneal limbus, including lacrimal fossa and semilunar folds (Figure 8.3.7. 102).
The suspensory ligament formed by the combination of inferior rectus muscle and inferior oblique muscle with fascia is attached to the inferior fornix (Figure 8.3.7. 103).
The bulbar conjunctiva is located on the surface of the eyeball and is the thinnest and most transparent part of the conjunctiva. The bulbar conjunctiva is divided into the sclera covering the sclera surface and the corneal limbus within 3mm from the corneal limbus. Here, the bulbar conjunctiva and the ocular fascia capsule are fused together, evolving from typical conjunctival epithelium to 10 layered squamous epithelium, and gradually transitioning to corneal epithelium. Because this is the epithelial transition zone, it is also the prone site of tumors.
Semilunar fold is a crescent-shaped conjunctival fold, located in the inner canthus, with its free edge facing the cornea, the lower corner reaching the vault, and a cavity on the outer free edge for storing tears. This kind of membrane is very developed in animals, called the blink membrane or the third eyelid, but it has degenerated in this part of human beings.
The lacrimal caruncle is a small red object, which is located in the semilunar fold and is a part of the lower eyelid. Its surface is stratified squamous epithelium, but there are large sebaceous glands, which are equivalent to meibomian glands. This is the origin of the white beaded secretion of the inner canthus. Its surface has 15 ~ 20 fine hairs, which are colorless and 0.2 long. The lacrimal caruncle is also a common site of tumors, such as hemangioma, pigmented nevus and meibomian adenocarcinoma.
5 conjunctiva histology The conjunctiva is divided into two layers: ① epithelial layer; ② Subconjunctival tissue. Subconjunctival tissue is divided into glandular layer and fibrous layer.
① Conjunctival epithelium: the junction of conjunctival epidermis and conjunctival epithelium at the palpebral margin is located at the rear edge of the opening of meibomian gland excretory orifice. The squamous epithelium here is non-keratinized epithelium. There are many unicellular mucous glands between conjunctival epithelium-goblet cells (especially between bulbar conjunctival epithelium), which secrete mucus to protect cornea. The density of conjunctival goblet cells changes with age. After birth 1 year is the fastest period of development change, and the cell density in childhood increases slowly until the cell density in adulthood reaches a relatively stable level of 30-70 goblet cells per 0. 1mm2 conjunctival surface. Severe damage to conjunctival epithelium and subconjunctival tissue leads to large-scale conjunctival scar formation, which is called substantive conjunctival xerosis; Vitamin A deficiency caused by systemic malnutrition and intestinal diseases is called xerosis conjunctiva. No matter what causes conjunctivitis xerosis, conjunctival epithelium will change from columnar to stratified squamous epithelium with more layers and keratinization on the surface, which is called dermoid.
The basal layer of corneal limbal epithelium often contains pigment, which gradually occurs after 6 months of birth. The bulbar conjunctiva can also contain pigment or even assemble into pigment spots.
Conjunctival epithelium changes with age. The baby's conjunctival epithelium has only two layers and is flat; After adulthood, the number of layers increased to 5 ~ 6, and the cell morphology changed from flat to columnar; When people get old, the conjunctival epithelium becomes flat again. Electron microscope shows that there are many microvilli in conjunctival epithelium, but there is no real desmosome-like structure between cells, which is the reason why conjunctival epithelium is not as firm as skin surface. In addition, epithelial cells contain many particles, such as pigment particles, lipid particles, keratin particles, mucus particles and swallowed foreign bodies. Epithelial cells at the corneal limbus increased to more than 65,438+00 layers, where the basement membrane was very irregular, with wavy wrinkles on the surface, and arranged radially at the corneal limbus, forming a ridge with pigment about 65,438+0 mm and 360, called vogt's palides, which was an important source of epithelial cells in the process of corneal wound repair.
Conjunctival epithelium and corneal epithelium are derived from ectodermal leaves during embryonic development, and they are anatomically connected at corneal limbus. In view of the anatomical and physiological dependence between bulbar conjunctiva, corneal limbus and corneal epithelium, Thoft et al. classified it as ocular epithelium.
Surface epithelium) has protective effect on deep tissue. In the sense of forming ocular surface, conjunctival epithelium and limbal epithelium can be transformed into corneal epithelium under certain conditions.
② Subconjunctival tissue layer: This layer is very loose. It is divided into shallow adenoid layer and deep fibrous layer. The former is looser and the latter is denser. Newborns have no adenoid layer. Appear gradually after 3 months of birth. In addition to reticular fibrous tissue, there are lymphocytes, histiocytes and mast cells. In the range of tarsal plate, lymphocytes can gather into large lymph nodes, which are distributed along the upper edge of tarsal plate. The deep fiber layer consists of collagen fibers, elastic fibers and blood vessels. But there is no such layer at the conjunctiva of the meibomian. It is fused with levator palpebrae superioris muscle and superior rectus muscle in the upper part of the fornix, and fused with inferior rectus muscle and inferior oblique muscle tendon in the lower part of the fornix, in the bulbar conjunctiva and eyeball fascia. The nerves and blood vessels supplying the conjunctiva pass through this tissue. Because the subconjunctival tissue is loose and elastic, it is very loose on the eyeball surface, and there is a buffer space when it is injured, which is not easy to break and it is easy to heal if there is a wound. Clinically, a small conjunctival wound (< 5 mm) can heal itself without suture. Large wounds should be aligned and sutured to avoid granulation tissue proliferation and scar formation, resulting in conjunctival sac deformity. The elasticity and toughness of conjunctival tissue change with age. In the elderly, elastic fiber degeneration, conjunctival elasticity and toughness decreased, and tissues became thinner. Therefore, the conjunctival flap is easy to tear during surgery in the elderly.
6 Conjunctival gland ① Mucous gland: Most conjunctival epithelium, especially between bulbar conjunctiva, has goblet cells secreting mucus. When these single-cell mucous glands are destroyed, conjunctiva will be dry and accompanied by tears.
② Serous gland: The accessory lacrimal glands such as Wolfring gland at the upper end of eyelid plate, Krause gland in fornix and lacrimal gland secrete tears, which can moisten and protect the cornea (Figure 8.3.7. 104).
7 Conjunctival vessels The bulbar conjunctiva is superficial and its blood vessels are clearly visible. Conjunctival blood vessels are very rich, which are characterized by more veins than arteries, direct communication between arteries and veins, direct anastomosis between veins and arteries. Under the slit lamp microscope, the direction of blood flow changes one after another. There are two sources of conjunctival artery: ① the arch of eyelid artery, which is formed by anastomosis of dorsal nasal artery and lacrimal artery; ② Anterior conjunctival artery, a small branch of anterior ciliary artery (Figure 8.3.7. 105).
The eyelid conjunctival artery comes from the eyelid artery arch, which forms the eyelid marginal artery arch at the inferior tarsal sulcus to supply the eyelid conjunctiva, and the end of the artery often expands into a ball. The branch of the marginal arterial arch located above the meibomian passes through the muscularis palpebrae and supplies the conjunctiva of the fornix. The blood supply of bulbar conjunctiva mainly comes from the posterior bulbar conjunctival artery, which is a branch of eyelid arterial arch, passes down through the fornix and is distributed in all bulbar conjunctiva except corneal limbus. Because the conjunctival artery mainly comes from the vascular system of the fornix, when conjunctivitis occurs, the closer the conjunctival congestion is to the fornix, the more obvious the congestion at the limbus of cornea is, which can be distinguished from ciliary congestion.
The blood supply of the bulbar conjunctiva around the cornea comes from the anterior conjunctival artery, which is a small branch of the anterior ciliary artery and branches from the rectus muscle before penetrating into the eye. The anterior conjunctival artery not only supplies the limbal artery plexus, but also branches to the bulbar conjunctiva near the limbal. Near the corneal limbus, there are not only the anastomotic branches of anterior conjunctival artery and posterior conjunctival artery, but also the communicating branches of conjunctival artery system and ciliary artery system. Therefore, severe conjunctivitis may cause mixed congestion (fig. 8.3.7. 106).
There are far more veins in conjunctiva than arteries, especially in the deep part of bulbar conjunctiva. There are three kinds of conjunctival venous return. Most of the venous blood from eyelid conjunctiva and bulbar conjunctiva returns to the posterior eyelid venous plexus, and some venous blood from eyelid conjunctiva directly returns to the superior and inferior veins of the eye. The deep vein of bulbar conjunctiva around corneal limbus plus vein of extraocular muscle, except for the rectus muscle, which has 3 veins, all the other rectus muscles have 2 veins. Because the conjunctiva has rich blood supply and strong resistance, it is easy to heal after being damaged.
8 lymphatic vessels of the conjunctiva There are abundant lymphatic vessels in the conjunctiva, and the subconjunctival tissues form two lymphatic networks. The superficial lymphatic network is small, and polygonal meshes are formed under the conjunctiva. The deep Linba pipe network is large and located in the subconjunctival fiber layer. Lymphatic fluid flows back to the inner and outer canthus, and there are several large lymphatic vessels at the limbus of cornea, such as two large collecting tubes, which surround the cornea in a semicircle from top to bottom, forming an incomplete lymphatic ring 7 ~ 8 mm behind the limbus of cornea, and sometimes small branches from the collecting tubes are parallel to the collecting tubes, where the upper and lower lymphatic vessels meet. There is also a large collecting duct in the lower part of the fornix, which flows into the outer canthus, then into the superficial lobe lymph nodes of the parotid gland before the ear, and finally into the deep cervical lymph nodes. Under the slit lamp, we can see that the lymphatic vessels of bulbar conjunctiva are different in thickness under normal circumstances, and their swollen parts are spindle-shaped, beaded or even spherical.
Lymphatic metastasis of eyelid tumor, the upper eyelid can reach the front of the ear, and the lower eyelid can reach the submandibular. Therefore, eyelid cellulitis is often accompanied by preauricular or submandibular lymph node enlargement, but there are no lymphatic vessels in the orbit. Orbital cellulitis generally does not cause lymphadenopathy (fig. 8.3.7. 107).
9 Conjunctival lesions Conjunctival vessels are abundant. Conjunctiva is in contact with the outside world and is more susceptible to infection by various external factors and microorganisms. Therefore, conjunctiva can form "red eye" due to infection and inflammation, and it can also be caused by simple conjunctival vascular congestion caused by internal and external environment, such as excessive drinking, habitual constipation, long-term irregular menstruation, ametropia, eye muscle imbalance, ciliary muscle overload and so on.
Conjunctival vascular congestion indicates extraocular conjunctival lesions, while ciliary vascular congestion indicates intraocular lesions, especially uveitis and elevated intraocular pressure. Histologically, conjunctival epithelium and corneal epithelium belong to the same source. Some conjunctivitis will spread to the cornea, causing a certain degree of visual damage. There are many unicellular mucous glands-goblet cells between conjunctival epithelium, which secrete mucus to protect cornea. If these goblet cells are destroyed in large quantities due to serious local lesions such as pemphigus, severe burns and drug allergy, serious conjunctival scars will be formed, and the surface of the eyeball will not be protected by mucus, which will lead to substantial conjunctival dryness and blindness. Conjunctival malignant tumor can cause damage to eyelid, eyeball or orbital contents, but it can be fatal.