Pterygium

Introduction of pterygium Pterygium is a common and frequently-occurring disease in ophthalmology. It is generally considered to be a chronic inflammatory lesion of local conjunctival fibrovascular tissue caused by external stimuli. It is triangular and can invade the cornea, involving single or both eyes. Its shape resembles the wing of an insect, hence the name pterygium. Traditional Chinese medicine is called "the scorpion". It is one of the most common ophthalmic diseases in the clinic and the oldest eye disease. It can not only cause eye irritation and appearance defects. It can also affect vision in varying degrees. It occurs mostly in outdoor workers and may be related to long-term stimulation such as sand, smoke, sunlight, and ultraviolet rays. basic knowledge Sickness ratio: 0.05% Susceptible people: no special people Mode of infection: non-infectious Complications: astigmatism

The cause of pterygium

At present, there are still many controversies about its pathogenic factors. It is generally believed that it may be the result of internal factors (genetic factors) and external factors (environmental factors). In external factors, ultraviolet rays in sunlight are the most important environmental factors, in addition to sand, dust, Drying, etc. are also important environmental factors that affect the onset of disease.

Environmental factors (19%):

Epidemiological survey results show that the incidence of people living in hot, sunny and dusty areas is significantly increased, and outdoor workers are also susceptible to this disease. Some people have found through experiments in rats that high doses of ultraviolet radiation can cause epithelium. Hyperplasia, anterior elastic layer degeneration and vascularization in the corneal stroma indicate that the formation of pterygium has a significant relationship with UV action and may be the most important environmental factor.

Genetic factors (12%):

Genetics has a certain effect on the occurrence of pterygium, but it does not play a decisive role. This inheritance is a dominant heredity with low penetrance, but it seems that the true lesion is not hereditary. The effects of environmental stimuli have a tendency to develop pterygium.

Immunity factor (26%):

Because plasma cells, lymphocytes, and immunoglobulins are found in pterygium, which are thought to be related to immunology, monoclonal antibody studies have shown that almost all lymphocytes are T cells that cause cell-mediated immune responses. And type IV hypersensitivity reaction, immunofluorescence studies show that immunoglobulin is IgG and IgE, IgG is mainly in the corneal stroma, which is consistent with the area infiltrated by plasma cells and lymphocytes, IgE is mainly distributed in the epithelium, matrix area, IgE Immunofluorescence studies showing type I or immediate hypersensitivity, normal conjunctiva, have not found IgG and IgE. If IgE persists, it will lead to chronic inflammation. The stimulation of this antigen can come from like pollen, dust particles or even viruses. Source factors, it is worth noting that although IgE is sometimes found by chance, this immunological theory still has some appeal. T lymphocytes, IgG and IgE are found in pterygium, which can indicate humoral and cell-mediated Hypersensitivity is closely related to the occurrence of pterygium.

Chronic inflammation and proliferative diseases (10%):

Chronic inflammation from any cause (such as focal conjunctivitis occurring at the edge of the limbus) can lead to inflammatory edema, repair and neovascularization, and a fibrovascular response characteristic of pterygium.

Other (16%):

Biedner et al believe that the occurrence of pterygium is related to the secretion of basic tears. Monselise et al. pointed out that angiogenesis can also promote the formation of pterygium. Some people think that there are many conjunctiva in the formation and development of pterygium, and the base of chronic corneal ulcer is considered to be mainly Conjunctival ulcers have also been suggested in recent years as the occurrence of pterygium is associated with limbal stem cell dysfunction.

Pathogenesis

The specific pathogenesis is still not fully explained. There are many theories about the pathogenesis of pterygium. In the early studies, it was found that there are a large number of lymphocytes in the pterygium tissue, plasma cell infiltration and mast cell response, which is considered to be pterygium. There is an immunological mechanism in the pathogenesis of meat. The study also found that IgG, IgE and a small amount of IgA and IgM exist in the pterygium tissue, and the basement membrane has granular immunoglobulin and C3 deposition, so the disease of pterygium is considered It is related to type I and type III allergies, but mast cells appear only in the subcutaneous matrix of the pterygium, especially near the denatured elastic fibers. They are not detected in the epithelial layer and the limbus, so it is currently impossible to judge the immune response. Whether the pterygium is a primary or secondary change in the pathogenesis.

Pterygium prevention

Prevention of pterygium is mainly to avoid smoke, sand and sunlight, eye health, eyelid or other types of conjunctivitis should be treated in a timely manner, at the same time should pay attention to adequate sleep, regular life, avoid dry stool and other general conditions. Prevent against environmental factors, avoiding the wind, sand, dust, pollen and other stimuli.

Pterygium complications Complications astigmatism

As the meat gradually advances toward the center of the cornea, it can cause corneal astigmatism. Once stretched to the pupil area, it can seriously impede vision. Large pterygium can affect the movement of the eyeball. Invasion of the cornea can cause different degrees of corneal opacity, but Corneal infective inflammation rarely occurs, and more complications occur during surgery, such as infection, conjunctival epithelial cysts, adhesion of the rectus muscles, adhesion of the eyeball, and thinning of the cornea leading to astigmatism.

Symptoms of pterygium common symptoms Corneal surface of the cornea on the conjunctiva of the conjunctiva of the cornea on the conjunctiva, conjunctival congestion and conjunctival congestion... Conjunctival papillary hyperplasia of the conjunctival edema and corneal ulcer

Clinically, it is roughly divided into primary caries (also divided into conjunctival phase and pre-corneal phase), advanced carcass (late corneal) and postoperative caries (also divided into cured caries and recurrent caries).

First hair

(1) Conjunctival period: the cleft palate conjunctival hyperemia and thickening gradually spread to the surface of the cornea, forming a triangular vascular tissue, resembling the wings of insects, hence the name pterygium, mostly on the nasal side The side of the sacral side is less. When extending to the cornea, it can invade the front elastic layer and the shallow layer. The conjunctiva under the slit lamp is thick, congested and edema, and the blood vessels are dilated. The tail is stuck with the half moon fold, and the moving ball conjunctiva is caused. A transverse strip, diiodopurine or fluorescein was washed and stained with cobalt blue light, and the conjunctival epithelium was spotted, and the conjunctiva covered by the lower eyelid was not colored.

(2) Pre-corneal fat: The triangular congestive fold formed by the thick conjunctiva, the head spans the limbus, the bottom is fan-shaped, and extends over the half-month folds to the sides of the tears. In the front of the limbus, it is the neck of the flesh. The head of the meat bulges on the limbus, extends to the cornea about 2 mm across the limbus, has tiny blood vessels on the surface, and has a gray-white vesicle at the end of the head. The small islands deposited by the particles invade the shallow layer of the cornea, which is the small island of Fuchs. The small island and the cornea around the head are opaque that is difficult to be recognized by the naked eye. The body also has gray-white stripes composed of particles, the blood vessels distributed along the limbus, the head and neck in the infiltrating hyperemia area and the corneoscleral adhesion, fluorescein staining. , showing epithelial punctate.

2. Progressive meat

The head is grayish-white rubber-like bulge, and its end forms a vertical jagged edge. The neck is filled with blood vessels and the tissue is thick. The surface of the head of the meat is slightly raised, and there is a scattered calcification point. The progress edge can pass over the center of the pupil and deep into the cornea. The front elastic layer has an epithelial bulge and turbidity.

Due to the pulling effect of the meat on the cornea, the curvature of the cornea can be changed to cause astigmatism. Habsen et al. examined 39 eyes and found regular astigmatism in the naked eye. The astigmatism can reach 5D, but most of the visual acuity does not decrease. Lin et al. The sensitivity of the naked eye was found to be significantly reduced in each spatial frequency, and it was found that the glare phenomenon was also significantly increased compared with the normal eye.

The meat can be stable for a long time, no obvious congestion, thick tissue, slightly raised head, gray corn infiltration in front of the cornea, and the meat is continuously pushed to the center of the cornea, called the stage.

There are many unconscious symptoms, but when the meat reaches the center of the cornea, it can cause astigmatism. If the pupil is covered, it will seriously affect the vision. The fat and contracture of the fat can limit the movement of the eye.

After the cornea has ulcers or burns, the conjunctiva of the ball and the cornea are called pseudo-pterygium. It can occur in any direction of the limbus, it is static, and only the head and the cornea adhere.

It is generally not difficult, although the changes in pterygium are very intuitive, but misdiagnosis often occurs. The following is the diagnostic criteria for pterygium: mature pterygium is a raised, triangular lesion on the cornea. The base is located at the conjunctiva next to the limbus, and the tip points to the center of the cornea. For example, the pterygium is artificially divided into three parts: the head, the neck and the body. The head is the part of the cornea, and the neck is the part of the limbus. The part is located on the surface of the sclera, and the mature pterygium often has a characteristic change in the corneal epithelium at the anterior edge of the head, which is characterized by a lipidal change in the corneal epithelium and subepithelial. This change usually has a transparent zone between the head and the head. Most pterygium is located in the cleft palate. If the initial lesion originates from the cleft palate, the diagnosis of primary pterygium should be cautious. In addition, the pterygium adheres to the limbus at the limbus. Pseudo-caries are sputum, adhesions of the conjunctiva, usually do not stick at the limbus, and can be distinguished by a glass rod under local anesthesia.

Examination of pterygium

It is easy to diagnose and must be differentiated from pseudo-caries. The latter can occur in any part of the limbus. It is a adhesion caused by inflammation or damage to the conjunctiva and cornea. Therefore, the probe can pass the probe, while the true fat is. No.

1. The expression of p53 protein in pterygium epithelial cells can be detected by Western blot. Some authors have found that p53 protein is abnormally expressed in pterygium epithelial cells. In some patients, p53 protein is inactivated, suggesting that pterygium may be a proliferative. disease.

2. Histopathological examination

Under the light microscope, the pterygium presents a region of varying thickness under the conjunctiva and the limbus of the sclera, with amorphous, eosinophilic, transparent or granular material accumulating, similar to denatured collagen, mixed with circles. Shaped or broken fibers, like an abnormal elastic tissue, the number of fibroblasts in the matrix tends to increase, appearing to be a reaction caused by damage. In addition, protein-like substances, acid mucopolysaccharides and calcification are found especially in old lesions. A small amount of aggregation of stones, initially believed that the accumulated matrix material is elastic tissue, because it can be stained by the stain of the elastic tissue, but because the tissue is resistant to non-proteolytic enzymes, ie, elastase, there is still controversy. The epithelium can be normal, atrophied or hyperplasia.

It is inferred from ultrastructural studies that there are four sources of elastic material formation: denatured collagen; pre-existing elastic fibers; abnormal activity of fibroblasts; abnormal matrix, which is generally considered to be due to their common inflammation of pterygium Degeneration changes occur. Most of the components of pterygium are composed of elastic fiber precursors and abnormally mature elastic fibers, and secondary degeneration (elastic tissue malnutrition) occurs.

According to the pathological process and pathological characteristics can be divided into 3 types:

(1) papillary proliferative type: equivalent to advanced pterygium, the composition of papilloma is thickened by conjunctiva and highly proliferating connective tissue under the epithelium, with edema, a large number of new blood vessels and a large number of round cells in connective tissue Infiltration, epithelial growth and deep wrinkles, resembling long tubular glands, edema epithelial cell nucleus staining deep and fine, cytoplasm clear, shaped like goblet cells.

(2) Fibrous type: equivalent to the initial hair, showing epithelial relaxation, edema, deep and dense nuclear staining, tightening of the epithelium, flattening of the cells, less blood vessels, no filling, compared with the proliferative type, less tissue cells.

(3) Atrophic and sclerotic type: equivalent to successful surgery, the development of sputum meat is stopped (clinical automatic atrophy is rare), the epithelium is significantly atrophied, the connective tissue under the epithelium is dense, hardened, transition to glassy degeneration, and the epithelium can be degenerated. Glass-like substance, even or missing, in the glassy denatured material, or calcification is observed, and the blood vessels in the connective tissue that have lost the original state due to degradation have partially atrophied. At this time, the naked eye can be observed to be converted into It is pale and tends to be flat.

Diagnostic identification of pterygium

diagnosis

Diagnosis can be performed based on clinical performance and laboratory tests.

Differential diagnosis

Sometimes it needs to be differentiated from plaque, pseudo-caries and squamous cell carcinoma.

False scorpion

False scorpion meat often has clear pathogenic causes such as inflammation, trauma, especially chemical injury, etc., can occur anywhere in the keratoconjunctiva, irregular shape, lesions are mostly static, and some pseudo-caries only have the head connected to the cornea The bottom probe near the limbus can pass, true pterygium is the result of chronic inflammation of the conjunctiva and subconjunctival tissue and develops into the cornea. Pseudopterygium is generally an acute injury of the limbal region of the cornea, near the bulbar conjunctiva Adhesion to the corneal lesions forms a conjunctival bridge.

2. Squamous cell carcinoma conjunctival squamous cell carcinoma

More common in the elderly, can occur in any part of the keratoconjunctiva, the bumps are uneven or papillary, rapidly infiltrating into the surrounding tissue, neovascular disorder, easy bleeding, and the tissue that invades the cornea is mostly irregular, if necessary, pathology A biopsy can confirm the diagnosis.

3. Cracks

The palpebral plaque is located in the conjunctival zone near the limbus of the limbus. It is a horizontal band, triangular or elliptical, bulging gray-yellow lesion. The pterygium is characterized by invading the cornea, while the palpebral plaque is not, but Occasionally, particularly large plaques may invade the cornea and be confused with pterygium.

4. Benign tumor of the limbus

Conjunctival papilloma is a translucent, lustrous red dome-shaped lesion that can be located on the nasal or temporal side near the limbus and confused with pterygium, but conjunctival papilloma rarely invades the cornea, histopathological examination The two can be distinguished. The corneoscleral cutaneous tumor often occurs under the ankle. It is a hemispherical bulge with a smooth white surface. It can be lightly congested and the surface can be seen. When it occurs on the temporal side, it should be differentiated from the pterygium.

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