fungal corneal ulcer
Introduction
Introduction to fungal corneal ulcer The fungal corneal ulcer was first reported by Leber in 1878. In the past, due to the low incidence, it was rarely mentioned in the literature. After the 1950s, reports of outside national value gradually increased. In the past 10 years, the disease has also increased significantly in China. In fact, some of the so-called "crowding corneal ulcers" that are not treated with antibiotics may be fungal and worthy of attention. basic knowledge The proportion of illness: 0.0005% Susceptible people: no special people Mode of infection: non-infectious Complications: iritis
Cause
Cause of fungal corneal ulcer
The fungus is directly invaded by corneal infection, and the necrotic tissue is scraped on the ulcer surface of the infected cornea for smear examination. The fungal hyphae can often be found, and the necrotic tissue is inoculated on the fungal culture medium, which can have fungal growth. There are dozens of pathogenic fungi in human corneas. There are 21 genera and 25 species in data analysis, mainly Aspergillus, followed by Fusarium.
From 1964 to 1976, 204 strains of fungi cultured from 318 cases of fungal corneal ulcer were identified by the Institute of Microbiology, Chinese Academy of Sciences.
From 1957 to 1965, 13 cases were reported in domestic literature. The strains were Candida albicans, Aspergillus, Fusarium, Yeast and Cephalosporium.
Foreign literatures are mainly Aspergillus, Fusarium, Candida albicans and Cephalosporium.
Most cases have a history of inducing onset. Most of the cases are closely related to vegetative lobular injuries during agricultural labor. In our case, the most common cause is the amputation of rice by threshing, followed by foreign matter such as plant leaf abrasion and dust. In the eyes, it can also be seen in long-term patients with other types of keratitis secondary to fungal infections, some people think that it is related to eye abuse of antibiotics or corticosteroids.
Corneal trauma causes epithelial damage, causing injuries such as rice, plant foliage or dust, etc. There are often fungi. When the corneal epithelium is damaged, the fungus can be inoculated into the cornea, causing the onset. The incubation period is usually 1 to 4 days, with an average of 2.4 days.
Prevention
Fungal corneal ulcer prevention
The vast majority of patients are farmers, although they can occur throughout the year, but mainly concentrated in the agricultural summer harvest and autumn harvest season.
1. Develop good hygiene habits, wash your hands frequently, and often cut your nails.
2, do not wear contact lenses for a long time, be careful when replacing contact lenses.
3, the same as the prevention of acute conjunctivitis, mainly to cut off the source of infection and attention to eye and hand hygiene.
4. It is forbidden for patients to bathe and swim in public places.
5, the treatment is mainly based on topical medication, drug oral administration and acupuncture also have a certain effect.
6, eat more foods and fruits with cold and heat and diarrhea, such as white, winter melon, bitter gourd, fresh sorghum, sugar cane, banana, watermelon and so on.
Complication
Fungal corneal ulcer complications Complications iritis
The disease is often accompanied by severe iritis reaction. The atropine must be used to fully enlarge the pupil. Corticosteroids have a diffusing effect on the ulcer, and it is not suitable for local or systemic use.
Symptom
Fungal corneal ulcer symptoms common symptoms tears eye pain corneal ulcer conjunctival edema and corneal ulcer keratitis conjunctival hyperemia photon necrosis
The diagnosis of fungal corneal ulcer is difficult, generally should start from the following three aspects.
1. History:
In one of the following cases, the pathogen should be further examined: 1 rural patients, history of agricultural trauma such as rice before the onset, or history of keratitis, or history of picking up foreign bodies; 2 long-term drip or subconjunctival injection Antibiotics and ulcers fail to control.
2, symptoms and signs:
1 often accompanied by white, yellow-white or gray-white ulcer in front of the empyema, the degree of development compared with the disease course, relatively chronic; 2 eye irritation symptoms and ulcer size contrast, relatively minor.
3. Pathogens:
1 ulcer necrotic tissue for scraping, can find fungal hyphae, the scraper is inoculated on the fungal medium, there may be fungal growth; 2 cell culture is generally negative, or only bacteria growth.
Fungal examination method: take the nectar examination of the necrotic tissue of the ulcer surface. If the fungal hyphae can be found, or the necrotic tissue can be cultured, and the fungus grows, it is the most reliable diagnosis basis. The specimen method is to first drop the surface anesthetic. Then use a pointed small blade to scrape a small piece of necrotic tissue with a diameter of 0.5 mm in the infiltrated dense area. As a specimen, the potassium sulphate smear is usually first examined. If there is still a specimen, it can be used for fungal culture at the same time. Once, the rabbit is used to damage the cornea in the pupil area. Do not take specimens deep in the ulcer to prevent ulceration and perforation.
When scraping specimens, it is sometimes possible to make a preliminary identification between fungal and bacterial. Generally speaking, the necrotic tissue of the fungal ulcer surface is "tough" or "toothpaste", the texture is loose, lack of viscosity; and the bacteria The necrotic tissue of the ulcer surface is "gel-like" and is sticky.
(1) fungal smear method: take a small piece of ulcerated necrotic tissue on a slide, drop a small drop of 5% potassium hydroxide solution on it, cover with a cover slip, slightly lightly press, check with high magnification microscope, ie Can be detected fungal hyphae, many often full of vision, but a small number of hyphae need to be carefully examined to find out, smear positive, generally can be diagnosed, the specimen should be checked at the time, can not be saved.
(2) Fungal culture method: Take a small piece of necrotic tissue and place it on the slope of solid potato or Sabouraud medium. If it can be inoculated on several mediums at the same time, it will help to increase the positive rate of culture and put it at 37 degrees Celsius. In the box, daily observation, there will be fungal organisms from the next day after the inoculation. If there is no growth after one week, it is positive. The culture method can observe the morphology, color and microscopic examination of hyphae, spores, etc. under the microscope. Identification of bacillary dysentery, preservation of strains and drug sensitivity tests, the positive rate of culture is generally low.
At the beginning, only the eye is sensitive or irritating, accompanied by blurred vision, history of trauma, ulcers within a few days after the injury, development is slow, and the rapid development of Pseudomonas aeruginosa corneal ulcer after trauma .
Early eyelid swelling and dizziness, tears and other irritating symptoms vary in severity. Most of the irritative symptoms in the severe stage are mild, and the congestion is often very serious, mainly mixed. In some cases, there may be a small amount of grayish white secretions.
Due to the difference in fungal strains, the duration of infection and the difference in individual conditions, the ulcer morphology seen in clinical practice is very inconsistent. Typical early ulcers are gray or milky white, often irregular, rough, dense, slightly higher. Out of the plane, the density distribution of ulcers and infiltration is uneven, and the corneal boundary between the ulcer and the healthy area is mostly clear, and the edge of the ulcer is often not neat.
Larger ulcers are often yellow-white, mostly irregular in shape, and the surface appears to be dry and rough. It is "tidal scale" or "toothpaste". The matrix is infiltrated and dense, the edge of the ulcer is slightly raised, the lesion is developed, and the knot around the ulcer is visible. Nodular or root-like matrix infiltration.
The following names are commonly used for fungal keratitis.
Hyphae Moss: It is a hyphae and necrotic tissue attached to the surface of the ulcer. The color is white and opaque, slightly bulging, and the cornea is clearly separated from the healthy area. It can be scraped off, and the ulcer surface after scraping is more transparent.
Mycelium: It is a lesion of fungal hyphae that grows into the corneal stroma. The surface is slightly dry and rough. The infiltration density of the turbid area is inconsistent and the texture is hard. When scraping with a knife, the scraping on the tip is very loose. The ulcer is still cloudy and opaque.
The edge of the hyphae: some ulcer edges are rough, sometimes infiltrating the roots of the tree, called "pseudo-foot"; or there is an isolated nodular round infiltration point around the ulcer, called "satellite stove."
Reaction ring: There is a circle of inflammatory bacteria infiltration around the mycelial stove, which is generally not too wide, about 1 to 2 mm. It is the defense response of the body to the hyphae. Some people call it the "immune ring."
Boundary sulcus: located in the middle of the mycelial lesion and the reaction ring, where the inflammatory cells infiltrate the most, which is a shallow ditch formed by shallow tissue necrosis and mild depression.
The slit lamp examination of fungal corneal ulcers, the development of ulcers from shallow to deep, the early ulcers are superficial, the corneal thickness is almost unchanged, and the bottom of the ulcer is densely infiltrated, reaching 0.2, 0.4 of the full thickness of the cornea. 0.6 unequal, although the matrix edema is light, but often full-thickness, facing the endothelium behind the hyphae, often edema rough and thick, accompanied by wrinkles, some people call it "endothelium plaque", sometimes the whole Diffuse haze edema in the cornea suggests that the ulcer is developing.
The development of ulcers often begins to infiltrate around or at the bottom, followed by the formation of abscesses, ulceration of necrosis and ulceration. The necrotic tissue of the ulcer surface melts and detaches, causing the cornea to become thinner and eventually lead to perforation.
The perforation is generally slow, the position, size and shape are uncertain. The perforation is often slightly bulged. Whenever the iris is exposed, the cornea is slightly conical at the central perforation, and the incidence of perforation is about 10%.
Sometimes the necrotic tissue does not fall off, the cornea has already appeared "water leakage" phenomenon, so that the anterior chamber disappears unconsciously, and sometimes in the necrotic corneal tissue, a little iris tissue is revealed, which is another sign of ulcer perforation.
Once the ulcer is perforated, the inflammation is gradually relieved, but compared with the perforation of the area, most of the anterior chamber is difficult to form again, and the ulcerated necrotic tissue is continuously detached, so that the transparent posterior elastic layer is completely exposed, the iris is clearly visible, and the normal can not be resisted. Intraocular pressure, which in turn develops into a local or total grape swelling of the cornea.
When the ulcer tends to heal, the eye pain is relieved, the irritation symptoms are improved, the viscous secretions disappear, the ulcer color changes from yellow-white to grayish white, the ulcer surface is clean, the surrounding epithelium grows inward, the fluorescein staining range is narrowed, and the anterior chamber empyema and spleen The phenomenon of the cornea and the deposition of the cornea are reduced. After the ulcer is healed, the corneal stroma remains infiltrated and edema, which often takes several months to absorb.
During the healing process of ulcers, new blood vessels can be inserted, and slender single branches are rare. The dense and short each is seen around the mycelium, which is similar to the cornea becoming smaller and the limbus moving inward.
Severe iritis ciliary reaction is one of the characteristics of fungal corneal ulcer. About 50% of cases may have anterior chamber empyema, from 1 mm or 2 to 3 mm. In a few cases, the accumulation of pus can reach more than half of the anterior chamber, or even full. The entire anterior chamber, the accumulation of pus is white or pale yellow, the former is the early phenomenon of ulcers, while the latter often represents the development of inflammation to a serious stage, the pus is thick, not easy to move, ulcers, abscess and anterior chamber empyema in the form It is easy to be confused, and it needs to be examined by slit lamp cutting to distinguish.
There are two types of post-corneal sediments, one is brown-gray powder or fine granules. Every time it is seen in the early stage of ulcers, the smaller area has no pus or a small amount of empyema in the anterior chamber, and the other is pale yellow pulp. Paste-like, or gray-white plaque, attached to the rough corneal endothelium, usually accompanied by anterior chamber empyema, anterior chamber empyema if not absorbed, and finally in the anterior chamber angle, iris, crystal surface formation membrane.
Fungal corneal ulcers have healed, epithelial growth, and fluorescein does not stain at all, there is still a possibility of recurrence in a short period of time, which is different from bacterial ulcers.
Examine
Examination of fungal corneal ulcer
1 ulcer necrotic tissue for scraping, can find fungal hyphae; the scraper is inoculated on the fungal medium, there may be fungal growth.
2 cell culture is generally negative, or only bacteria grow.
Slit lamp examination, the development of ulcers from shallow to deep, early ulcers are superficial, corneal thickness is almost unchanged, the bottom of the ulcer is dense matrix infiltration, up to 0.2, 0.4, 0.6 of the full thickness of the cornea, matrix Although the edema is light, it is often full-thickness. It is opposite to the endothelium behind the hyphae. It often has edema rough and thick, accompanied by wrinkles. Some people call it "endothelium plaque", sometimes diffuse fog appears throughout the cornea. Edema, suggesting that the ulcer is developing.
Diagnosis
Diagnosis and diagnosis of fungal corneal ulcer
diagnosis
Some ulcers are very bacteriological and must rely on careful clinical examination and pathogen diagnosis.
1, according to clinical manifestations, combined with ulcer formation, reference etiology and medical history can generally make a preliminary diagnosis.
2, the scraping of the bacteria for bacterial staining, culture, help to confirm the diagnosis.
