Brow arch pain
Eyebrow bow pain, that is, pain in the eyebrow arch, is a clinical symptom of bacterial keratitis. Bacterial keratitis is the most important infectious corneal disease in the 1960s. After the 1970s, viral keratitis, fungal keratitis, and Acanthamoeba keratitis increased rapidly, but bacterial keratitis still It is the most common infectious keratopathy with the highest incidence and blindness rate.
(1) Causes of the disease
The pathogenic bacteria have changed a lot with the changes of the times. In the 1950s, pneumococci were dominant; in the 1960s, Staphylococcus aureus dominated; in the 1970s, Pseudomonas aeruginosa dominated; in the 1980s, Pseudomonas aeruginosa was relatively reduced due to the use of aminoglycoside antibiotics. Penicillin-resistant Staphylococcus is relatively abundant; since the 1990s, other Gram-negative bacteria, such as non-fermenting Gram-negative bacilli, Serratia marcescens, and anaerobic bacteria, have gradually increased. Comprehensive domestic and foreign literature, the current common pathogenic bacteria.
Among the most common pathogenic bacteria, there are four species, Gram-positive bacteria Streptococcus pneumoniae (S) and Staphylococcus aureus (S), and Pseudomonas aeruginosa in Gram-negative bacteria. (pseudomonas aeruginosa, P) and Moraxella (M) are referred to as SSPM infections. According to the statistics of 120 cases of bacterial keratitis in Yokohama University in Japan, SSPM infection accounted for 72.5% (87 cases), and the above four pathogenic bacteria were 15% (18 cases), 11.7% (14 cases), 35.8. % (43 cases), 10% (12 cases), the United States, Canada also have the same statistical results. This tendency not only occurs in industrialized countries, but also in developing countries. In the Philippines, the number of SS2 infections was 92.2% (1624), which were 4.7% (83 cases), 42.31% (745 cases), 26.6% (468 cases) and 18.6% (328 cases).
Trauma is one of the most common risk factors for bacterial keratitis. In occupational anterior segment trauma, 6% of bacterial keratitis occurs. In rural areas, 5% of patients with corneal abrasions develop bacterial infections. Various causes of trauma to the corneal epithelium and matrix, first expose the corneal stromal tissue to the normal flora of the conjunctival sac, which is easy to cause bacterial infection; corneal foreign body and splashed water source are important carriers of external bacteria entering the cornea; In the presence of chronic bacterial blepharitis or dacryocystitis, bacteria in these areas can easily cause corneal infection.
In developed countries, wearing contact lenses is the most common risk factor for bacterial keratitis. All types of contact lenses may cause bacterial infection of the cornea, and soft contact lenses have the highest proportion of overnight wearers. Statistics show that the incidence of corneal ulcers in hard contact lens wearers is 0.02% per year, 0.04% for breathable rigid contact lenses, 0.04% for daily wear soft contact lenses, and traditional soft contact lenses are worn day and night. The rate is 0.2%. Wearing contact lenses causes corneal bacterial infection, and the contact lens itself has an effect on the structure and function of the corneal epithelium, bacterial contamination of the lens and lens case, wearing and nursing methods, and the wearer's life and hygiene habits. .
Among ocular surface diseases, abnormalities in tear volume and tear composition and destruction of eyelid closure function are common factors associated with corneal bacterial infection. All lesions that cause corneal epithelial destruction such as monocystic corneal epithelial lesions, epithelial cell poisoning caused by long-term use of antibiotics or antiviral drugs, local long-term use of glucocorticoids, and follicular keratopathy caused by endothelial decompensation, And a variety of degeneration and malnutrition involving the corneal epithelium, may be secondary to bacterial infection.
The clinical manifestations of corneal bacterial infection are the result of a combination of bacterial and host responses.
There are many kinds of bacteria causing keratitis, including Micrococcal (mainly Staphylococcus and Micrococcus), Streptococcus, Pseudomonas and Enterobacteriaceae, and about 87% of bacterial keratitis is It is caused by the above four types of bacteria. The distribution of bacteria is different depending on factors such as region, environment, life and sanitation. According to the statistics of the Department of Ophthalmology, Beijing Eye Institute from 1989 to 1998, Pseudomonas aeruginosa, coagulase-negative staphylococci, pneumococcus, coryneform bacteria and Staphylococcus aureus are the main pathogens of bacterial keratitis.
1. Staphylococcus aureus keratitis: Staphylococcus aureus is capable of producing plasma coagulase. A variety of virulence factors can be produced in infected tissues, and can be classified into two types according to their effects: factors related to the spread of infection and factors related to toxicity.
(1) Factors related to infection spread include: hyaluronidase, lipase, phospholipase, nuclease, gelatinase, plasmin, protease, and lytic enzyme.
(2) Toxicity-related factors: endotoxin A, B, C, D and E, hemolytic toxins a, p, 7 and 8, toxic shock syndrome toxin-1, and epidermolysis toxins A and B. The plasma coagulase of S. aureus forms a layer of fibrin membrane around the bacteria, which surrounds the lesion to form an abscess. Hemolytic toxins have the function of killing white blood cells.
2. Coagulase-negative staphylococcal keratitis: The bacteria itself does not secrete strong toxins, generally belonging to attenuated bacteria or conditional pathogens. The pathogenesis of corneal lesions is slow, and a biofilm is formed around the bacteria. The membrane is composed of glycoprotein secreted by bacteria and covers the surface of the bacteria, and the bacteria adhere to the surrounding bacteria by the membrane to form bacterial spots. In this state, the resistance of bacteria to antibiotics is significantly enhanced, making the drug difficult to work.
3. Pneumococcal keratitis: The pneumococcal capsule can escape the phagocytosis of neutrophils, so it is easy to invade the corneal tissue and spread rapidly. The bacteria secrete lysin, neuraminidase and hemolytic toxins, causing tissue damage. In addition, the immunoglobulin A-degrading enzyme produced by this bacterium can hydrolyze almost all secretory IgA involved in the local immune response, and the local non-specific immune function of the eye is inhibited.
4. Pseudomonas aeruginosa keratitis: Pseudomonas aeruginosa infection is mainly related to the virulence and invasiveness of bacteria, in addition to the decline in eye defense ability. The bacteria are capable of producing important pathogenic substances such as exotoxin A, elastase, and extracellular enzymes. Under the action of Pseudomonas aeruginosa flagella and protease, bacteria are easily transferred to the site of tissue damage; mucopolysaccharide protein complex makes bacteria adhere to the surface of tissue cells; elastase, alkaline protease and cytotoxin and hemolytic toxin Conducive to its invasion and reproduction, and cause necrotic damage of the corneal stroma.
5. Moraxella keratitis: The pathogenicity of Moraxella in different species is similar in the eye. The bacterium produces proteases and endotoxins that break down the corneal tissue. Some strains of Moraxella produce enzymes and toxins similar to phospholipases, hyaluronidase and hemolytic toxins.
6. Actinobacterial keratitis: The proportion of keratitis caused by Nocardia is less than 1 in 100 in infectious keratitis. Nocardia is an organism that grows in an obligate cell and can multiply in phagocytic cells without producing exotoxin, which is slower. The cell wall contains lipopeptides and lipopolysaccharide components, which vary from strain to strain and from growth to growth. Iron ions are an important factor in the ability of Nocardia to multiply in cells. The Nocardia infection of the cornea is often secondary to minor damage, and both humoral and cellular immunity participate in the defense mechanism.
7. Streptococcal keratitis: Streptococcus can produce a variety of toxins, mainly hemolytic toxins and erythrotoxin. Hemolytic toxins are cytotoxic; erythrotoxin is an exotoxin. Streptococcus can also produce a range of enzymes, mainly streptokinase and hyaluronidase. The former can activate plasminogen to plasmin and dissolve fibrin; the latter decomposes the extracellular matrix, which is beneficial to the spread of bacteria.
8. Salmonella keratitis: It is difficult for Salmonella to invade normal corneal tissue. Only when the corneal epithelial barrier is disrupted can the bacteria invade the corneal stroma and multiply. The experiment confirmed that the degree of lesion of keratitis caused by Serranosus is positively correlated with the amount of proteolytic enzymes secreted by bacteria. The amount of proteolytic enzyme produced by virulent strains is high, and the corneal lysis and necrosis reaction is obvious; on the contrary, the protein of attenuated strains The amount of hydrolase secretion is small and the tissue damage is also light.
9. Acne Propionibacterium keratitis: Because normal human conjunctiva is relatively hypoxic, there are often various anaerobic bacteria, of which 40% to 85% are P. acnes. The bacterium is a conditional pathogen, and infection is generally associated with mucosal barrier destruction and tissue hypoxia and necrosis. The polysaccharide released by this bacterium has leukocyte chemotaxis, and bacteria can multiply in cells. Propionibacterium acnes is often infected with other aerobic or anaerobic bacteria.
Most bacteria can invade the corneal stroma only when the corneal epithelium is damaged. Once the bacteria enters the cornea, polynuclear leukocytes (PMN) become chemotaxis, and release of lytic enzymes leads to stroma necrosis. In the case of infection of some highly toxic bacteria such as Pseudomonas aeruginosa, in addition to the above reasons, proteolytic enzymes can also be produced during bacterial reproduction, so the condition is more serious and rapid. Although the posterior corneal elastic membrane has a certain resistance to bacterial penetration, corneal perforation eventually occurs.
Ophthalmic examination corneal examination
1. The clinical manifestations of keratitis caused by different pathogen infections are not the same.
2. Symptoms: The onset is more urgent, the symptoms are heavy, redness, pain, photophobia, tearing, decreased vision, tingling in the eyes, foreign body sensation, and pain in the eyebrows. Increased eyelids and secretions.
(1) signs outside the cornea: ciliary congestion, swelling of the eyelids, conjunctival hyperemia and edema, iris congestion (expressed as iris discoloration and pupil dilation).
(2) corneal signs: corneal infiltration, corneal ulcer, corneal edema, posterior elastic membrane bulging, post-corneal deposition, anterior chamber empyema and corneal perforation. The clinical manifestations of corneal ulcers caused by different bacteria are very different. Table 3 is the main difference between SSPM-infected corneal diseases.
4. Pathological evolution process: The following is a simplified diagram (Figure 2) to outline the pathological evolution of bacterial keratitis:
The diagnosis of bacterial keratitis can be determined based on the current medical history, risk factors, and the original eye and systemic diseases. As mentioned earlier, a variety of factors can alter the clinical manifestations of bacterial keratitis. Antibiotic therapy or antibiotic-corticosteroid combination therapy can also affect and alter the typical clinical features of a visit. Laboratory diagnosis must be performed to determine bacterial corneal infections.
Brow arch cyst: is a type of dermoid cyst. The dermoid cyst is a congenital skin-like neoplasm. Due to abnormal development of the embryonic stage, part of the ectodermal rupture is buried under the skin or conjunctival tissue. It is easy to occur in the inner or outer part of the eyelid, and the site of occurrence is related to the sacral suture, which often originates from this kind of suture. It can also occur in eyebrows, tendons, and conjunctiva.
Brow-bow depression refers to the defect of the dermis and subcutaneous tissue of the eyebrow skin, which may cause depression and is often caused by hemorrhoids, trauma, and chickenpox.