Trachoma is a chronic infectious conjunctivitis caused by Chlamydia trachomatis. Trachoma is named for its rough and uneven appearance on the surface of eyelid conjunctiva, which looks like sand. Trachoma, which means trachoma in English, comes from the Greek trachys, which also means rough. Conjunctival infiltration such as nipple and follicular hyperplasia appeared in the early stage of the disease, and corneal pannus appeared at the same time. In the late stage, the affected eyelid conjunctiva is scarred, which leads to eyelid varus deformity, aggravates corneal damage, and even affects vision and even blindness. Trachoma was the main cause of blindness in China before liberation. After liberation, trachoma has been widely prevented and treated under the care of the party and the government. With the improvement of people's living standards and medical and health conditions, the incidence of trachoma has been greatly reduced. From the epidemiological sampling survey of blindness and low vision in Shunyi County, Beijing, Shanghai, Yunnan, Shaanxi and other places (1988), it can be seen that the main causes of blindness in most of the above areas are non-communicable diseases such as cataract and glaucoma. However, the survey results in Yunnan Province show that among the 6.5438+0.8 million blind patients in Yunnan Province, cataracts account for 654.38+0, about 80,000; Trachoma and its complications accounted for the second place, about 30 thousand people. Therefore, trachoma plays an important role in the causes of blindness in China. In addition, this disease is still the main cause of blindness in many developing countries in Asia and Africa.
etiology
It has long been known that trachoma secretions can infect this disease. In 1907, Halberstaedter and VonProwazek stained with optical microscope and Gimsa, it was found that inclusion bodies, that is, red and blue precursors and deep blue precursors, gathered in epithelial cells of trachoma. This inclusion body is surrounded by a matrix and is mistakenly called "Chlamydia". Since then, many studies have been carried out, but no pathogens have been isolated. During 1954, Tang cooperated with Zhang. While examining and treating a large number of patients, we inoculated monkeys' eyes with secretions from patients' eyes, and inoculated mice's brains with secretions from trachoma patients, and the results were completely negative. 1955 was inoculated with chicken embryos, and active trachoma cases without complications and drug treatment were selected. Streptomycin was used to kill the bacteria in the sample, and finally the first isolation and culture was successful in 1956. Since then, a new upsurge of trachoma research has been set off around the world. Because this pathogen can pass through the bacterial filter and parasitize in cells to form inclusion bodies, it was considered to be a virus at that time. It is also recognized that its size and shape are different from ordinary viruses, and it is called atypical or large viruses. Later, scholars from all over the world further studied its molecular biology and metabolic function, and proved that it has RNA, DNA and some enzymes, propagates in a binary way, has cell membrane and cell wall, is sensitive to antibiotics, and does not conform to the basic properties of the virus. But it is similar to G bacteria to a great extent. In 197 1, Storz and Page proposed to name this kind of microorganism Chlamydia. Bergey's Handbook of Bacterial Identification published by 1974 accepted this classification: divided into prokaryotic cell kingdom, fern, rickettsia, chlamydia, chlamydia, chlamydia, including Chlamydia trachomatis and Chlamydia psittaci. In the 10 manual published in 1989, a new species of Chlamydia pneumoniae was added. Chlamydia trachomatis is subdivided into three biological variants: trachoma, lymphogranuloma and mouse pneumonia. Among them, the biological variants of trachoma can be divided into three immune types: A, B, Ba, C, D, E, F, G, H, I, J and K 12, and the biological variants of lymphogranuloma can be divided into L 1, L2 and L3.
Generally speaking, endemic blinding trachoma is mostly caused by type A, B, Ba and C, and some functions say that these types are mostly caused by epidemic chlamydia trachomatis. D ~ k type mainly causes urogenital infection; Such as urethritis, cervicitis and epididymitis. And inclusion body conjunctivitis, so it is called ocular-urogenital chlamydia. In 1966, Wang Kegan and Zhang of China used the mouse toxin protection test to divide 46 kinds of Chlamydia trachomatis isolated from different regions of China in 10 into two immune types: type I represented by TE-55 and type II represented by TE- 106, with a ratio of 2∶ 1. However, the corresponding relationship between types ⅰ and ⅱ and the immunophenotype of 15 above has not been determined. Zhang, Zhang, et al. (1990) The immunofluorescence test was used to detect the immunophenotype of Chlamydia trachomatis in North China. The results showed that the prevalence of trachoma in North China was mainly type B, followed by type C..
Chlamydia trachomatis can infect human conjunctiva and corneal epithelial cells There are two biological stages in its life cycle: the protozoa is infected, with a size of about 0.3μm and a cell wall, which can survive outside the cell; The initial body, also known as reticular body, is a reproductive stage, with a large volume of about 0.8μm and no infectivity. After the protoplasm invades the host cell, it develops into a precursor in the cytoplasm and forms the daughter protoplasm by binary division. When the cytoplasm is full, it will burst and release protozoa, and the free protozoa will invade normal epithelial cells and start a new cycle. Each cycle is about 48 hours.
Trachoma primary infection, can not leave scars after healing. However, in epidemic areas, sanitary conditions are poor and repeated infections often occur. Primary infection has sensitized conjunctival tissue to chlamydia trachomatis, which will cause delayed hypersensitivity when chlamydia trachomatis is encountered again. Trachoma is often acute in the course of chronic diseases, which may be the manifestation of repeated infection. Repeated infection aggravates pannus and scar formation of trachoma, and even the tarsal plate thickens and deforms, causing entropion of eyelids, aggravating corneal opacity, damaging vision and even blindness. In addition to repeated infections, other bacterial infections will also aggravate the condition.
pathological change
Chlamydia trachomatis only invades epithelial cells of eyelid conjunctiva and fornix conjunctiva, but the lesions caused by Chlamydia trachomatis reach deep tissues. At first, the epithelial cells in the surface layer degenerated and fell off, while the epithelial cells in the deep layer proliferated. With the development of the disease, epithelial cells proliferate rapidly, making the epithelial layer no longer smooth and forming nipples. There are dilated capillaries, lymphatic vessels and lymphocytes in the nipple essence. At the same time, diffuse lymphocyte infiltration appeared in conjunctival subcutaneous tissue, and localized local aggregation occurred at the same time, forming follicles. There are many lymphocytes, macrophages and reticulocytes in the center of the follicle, and there are a lot of small lymphocytes around it. With the progress of the disease, follicles degenerate, and then connective tissue proliferates to form scars. There is also diffuse lymphocyte infiltration in meibomian, which leads to hypertrophy, and in severe cases, connective tissue hyperplasia and deformation. Corneal pannus begins at the upper part of corneal limbus, and corneal microvascular expansion develops to the central part of cornea, accompanied by cell infiltration, initially located in the shallow layer, and then develops to the lower layer and deep layer of cornea. It is covered at first, but it can invade all corneas in severe cases.
clinical picture
The incubation period is about 5 ~ 12 days. It usually invades the eyes. Most of them occur in children and adolescents.
1. Most symptoms are acute. The patient has foreign body sensation, photophobia, tears, and a lot of mucus or mucus secretions. After several weeks, the acute symptoms subsided and entered a chronic phase, at which time there was no discomfort or only eye fatigue. If you heal yourself or yourself at this time, you can leave no scars. However, in the chronic course of disease, in epidemic areas, repeated infections often occur, and the condition is aggravated. When there is active pannus on the cornea, the irritation symptoms become obvious and the vision decreases. In the late stage, the symptoms of sequelae are more obvious, such as entropion, trichiasis, corneal ulcer, dry eyeball, etc., which seriously affects vision and even blindness.
2. Symbols
⑴ Acute trachoma: Acute follicular conjunctivitis, eyelid swelling, conjunctival congestion, nipple hyperplasia causing eyelid conjunctiva roughness, upper and lower fornix conjunctiva covered with follicles, combined with diffuse keratodermatitis and preauricular lymphadenopathy. After a few weeks, the acute inflammation subsided and turned into a chronic phase.
⑵ Chronic trachoma: Due to repeated infection, the course of disease can be delayed for several years to more than ten years. Although the degree of congestion is reduced, there is diffuse cell infiltration with subcutaneous tissue, conjunctival contamination thickening, nipple hyperplasia and follicular formation (figure 1). Follicles vary in size and have a gelatinous appearance, and the lesions are obviously in the upper fornix and conjunctiva on the upper edge of eyelid plate. The same lesions can also be seen in the lower eyelid conjunctiva and the lower fornix conjunctiva, which can even invade the semilunar fold wall in severe cases. Corneal pannus: It is a normal capillary network outside the corneal limbus, which passes through the corneal limbus and enters the transparent cornea, affecting vision, and gradually develops to the pupil area, accompanied by cell infiltration, and develops into a shallow small ulcer, which can form a corneal facet after healing. When cell infiltration is serious, thick pannus can be formed.
In the process of chronic diseases, conjunctival lesions are gradually replaced by connective tissue, forming scars. It first appeared in the tarsal sulcus under the conjunctiva of the upper eyelid, showing horizontal white stripes, and then gradually became a net. When the active lesions completely subsided, all the diseased conjunctiva became white and smooth scars.
The course and prognosis of trachoma vary according to the severity of infection and whether it is repeatedly infected. Mild or no recurrent infection can be cured within a few months, leaving a thin scar or no obvious scar on the conjunctiva. In severe cases, repeated infection can last for several years to more than ten years, while chronic diseases can be infected by other bacteria, and repeated infection often leads to acute attacks. Finally, large-scale scarring is no longer contagious, but there are serious complications and sequelae, which often reduce vision and even blindness.
In order to prevent trachoma and meet the needs of investigation and research, there are many clinical staging methods for trachoma. 65438-0979 During the discussion of the Second National Ophthalmology Academic Conference, the stage of trachoma was redefined:
Stage I-progressive stage: that is, in the active stage, papillae and follicles coexist at the same time, the conjunctival tissue of the upper fornix is blurred, and there are corneal pannus.
Stage Ⅱ —— Fading stage: From the beginning of scar appearance to most of them becoming scars. There are only a few active lesions left.
Stage ⅲ-complete scarring stage: active lesions completely disappear, replaced by scars, no infection.
At the same time, the grading standard is established: according to the number of active lesions (nipples and follicles) in the total area of upper eyelid conjunctiva, it is divided into two levels: mild (+), moderate (++) and severe (++). Coverage of less than 1/3 is (+), that of 1/3 ~ 2/3 is (++), and that of more than 2/3 is (++).
The classification method of corneal pannus is determined: the cornea is divided into four parts, in which pannus invades within 1/4 (+), reaching 1/4 ~ 1/2 (++) and reaching1/3 ~ 3/.
Mccullen staging method commonly used in the world:
Stage I-initial stage of infiltration: the conjunctiva of eyelid and fornix is hyperemia and hypertrophy, especially in the upper part, with early follicles and early pannus of cornea.
Stage Ⅱ-active stage: There are obvious active lesions, namely papillae, follicles and pannus of cornea.
Stage Ⅲ-Pre-scar: Same as Stage Ⅱ in China.
Stage Ⅳ-complete scarring stage: the same as the third stage in China.
diagnose
Typical trachoma is easy to be diagnosed according to the appearance of nipple and follicular hyperplasia, corneal pannus and eyelid conjunctival scar. Early diagnosis of trachoma is still difficult. Sometimes it can only be initially diagnosed as "suspected trachoma". According to the decision of Ophthalmology Branch of Chinese Medical Association No.65438-0979, the diagnosis basis of trachoma is as follows: ① The blood vessels of upper fornix and upper eyelid conjunctiva are blurred and congested, nipple hyperplasia or follicular formation, or both. ② Corneal pannus can be seen with magnifying glass or slit lamp. ③ Scar appears in the upper fornix or/and upper eyelid conjunctiva. ④ Trachoma inclusions were found during conjunctival curettage. On the basis of item 1, one of the other three items can be used to diagnose trachoma.
Suspected trachoma: hyperemia in the upper fornix and conjunctiva at the corner of the eye, with a small number of papillae (papillae is normal tissue) hyperplasia or follicles, and other conjunctivitis has been ruled out.
differential diagnosis
1. Conjunctival follicular disease is common in children, bilateral and without conscious symptoms. Hair follicles are more common in the lower fornix and lower eyelid conjunctiva. Follicles are small and uniform, similar in size, translucent, with clear boundaries, normal conjunctiva between follicles, no congestion, no pannus of cornea and no scar. Trachoma follicles are mostly found in the upper fornix and upper eyelid conjunctiva, which are turbid, uneven in size and irregular in arrangement, with symptoms such as conjunctival congestion and hypertrophy.
2. Chronic follicular conjunctivitis is common in school-age children and adolescents, all of which are lateral, and Echinococcus granulosus may be the cause. There are often secretions in the morning, and my eyes are uncomfortable. Follicles are more common in the lower fornix and lower eyelid conjunctiva, with uniform size and orderly arrangement; Although the conjunctiva is congested, it is not hypertrophy; 1 ~ 2 years after self-healing, no scar formation; No pannus of cornea.
3. Conjunctivitis in spring is seasonal, and its main symptom is itching. The nipple on eyelid conjunctiva is large, flat and hard, and there is no lesion in the upper fornix, which is easy to distinguish. Eosinophils increased in secretion smear.
4. Inclusion conjunctivitis Inclusion conjunctivitis in adults and newborns can be seen in conjunctival curettage, and its shape is the same as trachoma, which is not easy to distinguish. However, all cases of inclusion conjunctivitis started with acute symptoms, with hair follicles attached to the lower fornix and conjunctiva of the lower eyelid and no pannus of cornea. Months to 1 year can heal itself without scar formation, which can be distinguished from trachoma.
treat cordially
Since the application of sulfonamides and antibiotics, the treatment of trachoma has been significantly improved. Experimental studies have proved that rifampicin, tetracycline, chlortetracycline, oxytetracycline, erythromycin, sulfanilamide and chloramphenicol have inhibitory effects on Chlamydia trachomatis.
1. External use of 0. 1% rifampicin or 0.5% chlortetracycline or tetracycline eye drops, 3 ~ 6 times a day, has a good effect. However, this kind of drug gradually fails after being dissolved in water for several weeks and needs to be re-formulated. If made into eye ointment or suspension, it can be stored for a long time. 10% ~ 30% sodium sulfacetamide and 0.25% ~ 0.5% chloramphenicol eye drops are easy to store and have good effects. The above drugs generally need to be used continuously for 1 ~ 3 months. Intermittent therapy is also feasible, that is, after taking medicine for 3 ~ 5 days, stop taking medicine for 2 ~ 4 weeks, and then take medicine. The effect is also good, easy to adhere to. For most people who are scarred and still have residual nipple hyperplasia "islands", copper sulfate pen can be used to corrode and promote scarring.
2. Systemic treatment of acute or severe trachoma, in addition to local drops, adults can take sulfanilamide preparations orally. Take it continuously for 7 ~ 10 days as a course of treatment, and stop taking it 1 week before taking it. It takes 2 ~ 4 courses of treatment, and attention should be paid to the side effects of drugs.
3. Surgical treatment of nipple hyperplasia is feasible. Rub eyelid conjunctiva and fornix conjunctiva with cotton swab or cuttlebone stick dipped in sulfanilamide or tetracycline. Squeeze most follicles, crush follicles with wheel forceps under local anesthesia, and discharge the contents. At the same time, combined with drug therapy to promote rehabilitation. To eliminate the sequelae of eyes, such as a few trichiasis can be electrolyzed, and those with trichiasis of eyelids need surgical correction.