Corneal opacity

Introduction The cornea is a transparent tissue with avascular structure. Transparency is the greatest feature of corneal tissue and is an essential element of its physiological function. Once it is affected by trauma or harmful factors, its transparency is lost and turbidity can cause visual impairment. Corneal opacity is generally seen by visual inspection. Lighter like a veil, the screen is slightly foggy, and the heavy one is magnetic white. However, very slight turbidity needs to be checked by special inspection. Corneal opacity can be all or limited. As long as turbidity is found, its properties should be further understood.

Cause

The transparency of the cornea is primarily dependent on the optical consistency of its tissue structure. Therefore, the integrity of the epithelium and endothelium, the alignment of the corneal stroma plate, the proper water content of the corneal tissue, and the avascular tissue of the cornea can maintain its transparency. Therefore, if some factors undermine the above basic conditions, corneal opacity can be caused. For example, inflammation leads to cell infiltration or opaque substance deposition, excessive moisture infiltrates into the corneal parenchyma through the damaged corneal endothelium, and corneal neovascularization or scar tissue caused by certain lesions destroys the regularity of the corneal plate and epithelial arrangement.

1. Congenital.

2. Infectivity. Including keratitis caused by bacteria, fungi, viruses, corneal ulcers.

3. Traumatic. Corneal perforation, contusion, blast injury, chemical burn, hot burn, etc.

4. Allergic reactivity. Such as vesicular keratitis.

5. Denaturation or malnutrition. Such as corneal old ring. Corneal band degeneration, lattice dystrophy, corneal softening, etc.

6. Scarring. Corneal cloud, leukoplakia, adhesion blood spots, corneal staphyloma and so on.

7. Corneal tumors. The originator is rare, and most of it originates from the conjunctiva or limbus.

8. Others. Corneal opacity is one of the signs of other eye diseases. Such as corneal edema, corneal depression, corneal neovascularization. Corneal blood staining, Keyier (Kayser-Fleischer referred to as KF ring) pigment ring, pterygium and so on.

an examination

Related inspection

Ultrasound examination of the eyeball and eyelids and CT examination of the sputum area Urine mucopolysaccharide detection slit lamp ophthalmoscopy

First, medical history

To understand the eye, time of onset, and detailed symptoms. Such as corneal opacity with redness, shame, tearing, pain, vision loss is the characteristics of corneal inflammation. If there is a history of trauma, you should ask about the specific circumstances of the injury, such as crop wounds, it may be a fungal infection. With a history of corneal foreign body removal, corneal ulcers progress rapidly, pay attention to Pseudomonas aeruginosa infection. If the cornea is mostly opaque, has no irritation and has a family history, there is a possibility of corneal degeneration. Has a history of trauma or keratitis, no irritating symptoms, only visual impairment, it may be a corneal scar.

Second, physical examination

Some corneal lesions are caused by other diseases of the body. Such as a cold can cause rash keratitis, herpes zoster can spread to the cornea, malnutrition in infants and young children due to vitamin A deficiency can cause corneal softening. Therefore, we should pay attention to the whole physical examination, which is conducive to diagnosis.

Eye examination: Corneal lesions can be examined with a 10x magnifying glass with a flashlight. Detailed lesions still need to be observed by slit lamp microscope combined with fluorescein staining. For example, keratitis opacity is mainly cell infiltration and edema, so the boundary of the turbid area is unclear, and the surface is tarnished with ciliary congestion. If it is a corneal scar, there is no ciliary congestion, the corneal turbidity is clear, and the surface is shiny. The fluorescent staining of the inflammatory person was stained, and the scar was not stained due to the integrity of the epithelium. Calcium deposition, etc. on the basis of the original white class, is corneal degeneration or malnutrition.

Third, laboratory inspection

1. Scrape and culture. Corneal ulcer scrapers quickly understand the pathogens, conjunctival sac secretions for bacterial or fungal culture.

2. Cytological examination. Cytological examination of the ulcer smear, the virus is a three-dimensional oval. The cytoplasm and nucleus infected under the fluorescence microscope showed yellow-green fluorescence.

3. Serological examination. It is meaningful for the diagnosis of herpes simplex keratitis.

Fourth, equipment inspection. Slit lamp microscopy combined with fluorescein staining is helpful for diagnosis.

Differential diagnosis

(a) superficial keratitis

1 The primary lesion can be caused by a virus. Epidemic keratoconjunctivitis caused by adenovirus type VII, epidemic hemorrhagic conjunctivitis caused by enterovirus. It can cause inflammatory infiltration under the corneal epithelium and epithelium. Fluorescein staining is punctately colored with varying thicknesses. In the case of herpes simplex epithelial infection, it is punctate, star-shaped or linear, and gradually develops into dendritic or map-like opacity.

2 secondary to the inflammation of adjacent tissues, such as heavier acute conjunctivitis, invading the peripheral part of the cornea, superficial corneal infiltration, edema, epithelial exfoliation, and more point-like opacity. Fluorescein staining was positive. If the lower third of the cornea has dense punctate dermatitis and erosion, often associated with staphylococcal eyelid inflammation.

(B) corneal stroma

Most of them are immune reactions, and can also be caused by direct invasion of pathogenic microorganisms. Congenital syphilis is the most common cause, tuberculosis, herpes simplex, banded sores, etc. can also cause the disease. A deep keratitis, the lesion is located in the deep layer of the corneal stroma, infiltrating turbidity and edema. The lesions are thickened with a posterior elastic layer wrinkle and have a frosted glass appearance. Vision loss, ciliary congestion, may be associated with iridocyclitis. In the late stage, the neovascularization is surrounded by the corneal stroma, which is brush-like and rarely branched. The cornea can still return to transparency after the inflammation of the light is subsided. If the substrate layer is necrotic, deep scars of varying thickness will be left behind.

(three) corneal ulcer

The cornea has a gray-white infiltration, the boundary is not clear, the surface is tarnished, followed by tissue defects forming ulcers, and fluorescein staining is positive. The severe irritant symptoms are obvious, the ciliary congestion is significant, the ulcer is large and deep, with anterior chamber empyema, and can be perforated.

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