Keratitis

Introduction Keratitis [Medicine] keratitis: Inflammation caused by bacteria and viruses invading the cornea due to corneal trauma. The affected eye has a foreign body sensation, a stinging or even a burning sensation. Conjunctival hyperemia on the surface of the conjunctiva, accompanied by symptoms such as fear of light, tearing, visual impairment and increased secretions. The surface of the cornea is infiltrated with ulcer formation. Corneal inflammation necessarily affects vision more or less, especially if inflammation invades the pupil area. The scar formed by the healing of the ulcer not only hinders the light from entering the eye, but also changes the curvature of the cornea surface and the refractive power of the refractive lens, so that the object cannot be focused on the retina to form a clear image, and thus the vision is lowered. The degree of vision involvement depends entirely on the location of the scar. If it is in the middle of the cornea, even if the scar is small, it affects vision.

Cause

1. External causes: Most of the corneal infections caused by external causes have two conditions:

a. Damage and shedding of corneal epithelial cells.

b. Simultaneous infection.

Infectious corneal ulcers are more likely to occur only if both conditions are available.

2. Internal cause: refers to an intrinsic disease from the whole body. There is no blood vessel in the cornea, so acute infectious diseases are not easy to invade the cornea. However, the corneal tissue participates in the systemic immune response, although the degree of immune response is lower than that of other tissues, but because it has no blood vessels and the metabolism is slow, the change of this immune response lasts for a long time, and the cornea is in a long time. It is in a sensitive state, so that allergic diseases such as vesicular keratitis are prone to occur.

3. Caused by the spread of adjacent tissues: due to embryonic homology and anatomical continuity, the disease that spreads to the corneal epithelium mostly comes from the conjunctiva, such as severe conjunctivitis and superficial keratitis.

an examination

Related inspection

Bacteriological examination of eye specimens for fungal culture examination

1. Check systemic and local pathogenic factors.

2. Suppurative inflammation should be smear examination, bacterial, fungal culture and drug susceptibility test.

3. Tree branch and shallow punctate keratitis for immunological examination.

Differential diagnosis

1. In addition to paralytic keratitis, most patients with keratitis have symptoms of inflammation, such as pain, shame, tearing, and eyelids. This is caused by inflammation of the trigeminal nerve endings in the cornea, causing reflex orbital muscle contraction and tear secretion. The cornea is an avascular tissue, but the adjacent area is rich in blood vessels (the blood vessels of the limbus and iris ciliary body). When the inflammation involves adjacent tissues, there is congestion and inflammatory exudation. Therefore, patients with keratitis not only have ciliary congestion, but also iris congestion. The latter manifested as iris discoloration and pupil dilation.

2. The exudate is from the same source. Edema can occur in the conjunctiva of the severe patient or even in the eyelids. Corneal infiltration occurs due to the movement of leukocytes to the corneal lesion due to hyperemia of the limbus. When the cornea is inflamed to the degenerative phase, the clinical irritation symptoms are greatly alleviated.

3, corneal parenchyma: refers to diffuse inflammation within the corneal parenchyma. It is mostly an expression of an antigen-antibody reaction, such as congenital syphilitic keratitis. But it can also be seen in the infection of tuberculosis, viruses and certain molds. The following is only a description of congenital syphilitic keratitis.

4. If keratitis is caused by mold, it is called fungal keratitis, and because the outer layer of mold has capsule protection, it is more difficult to kill than ordinary bacteria. If the eye is infected, the mold will rapidly multiply and penetrate into the eye tissue. There are symptoms such as red eyes, pain and blurred vision. At this time, only topical or oral anti-mold drugs can be used. In severe cases, even corneal ulcers and corneal perforations become blind and corneal transplantation is required.

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