What Is a Corneal Infection?

The keratitis caused by various factors is collectively called keratitis. It is one of the common diseases in ophthalmology and one of the major blinding diseases in China. The cornea is located in the forefront of the eyeball and is in direct contact with the outside world. It is susceptible to damage by microorganisms, trauma and physical and chemical stimuli and inflammation. The clinical manifestations are blurred vision, pain, photophobia and tearing, and obvious vision loss. Ophthalmological examination showed loss of corneal gloss, decreased transparency, and ulcer formation. In severe cases, corneal perforation, intraocular infection, and even blindness may occur. At present, keratitis is divided into infectious, immune, malnutrition, neurological palsy and exposure according to the cause. Infectious keratitis mostly occurs in the central area of the cornea, while immune keratopathy easily occurs in the periphery of the cornea.

Basic Information

English name

keratitis

Visiting department

Ophthalmology

Common causes

Bacteria, fungi, viruses, chlamydia, Acanthamoeba infection, autoimmune factors, trauma, and systemic diseases

Common symptoms

Pain, photophobia, tearing, eyelid spasm and other irritations and ciliary congestion, cloudy corneal infiltration or ulcers

Causes of keratitis

Infection

Is the most common cause of keratitis. Pathogenic microorganisms include bacteria (such as pneumococcus, Staphylococcus aureus, hemolytic streptococcus, Pseudomonas aeruginosa, gonococcus, etc.), viruses (herpes simplex virus, adenovirus, etc.), fungi , Acanthamoeba, Mycoplasma, Chlamydia, Treponema pallidum, etc. It is usually caused by damage, shedding of corneal epithelial cells, or a decrease in body resistance. Corneal epithelium is extremely prone to infectious inflammation after injury. Therefore, corneal foreign bodies, corneal abrasions, incorrect use of contact lenses, eye contact with contaminated drugs or water sources are common susceptible factors for infectious keratitis. Patients with diabetes, malnutrition, and chronic wasting diseases also suffer from resistance. Reduced strength and susceptibility to keratitis.

Internal cause

Refers to an endogenous disorder from the entire body. Such as some autoimmune diseases, or other systemic diseases (such as vitamin A deficiency, trigeminal nerve damage) affect the cornea.

The cornea has no blood vessels, so acute infectious diseases do not easily invade the cornea. However, the corneal tissue participates in the whole body's immune response. Although the degree of the immune response is lower than that of other tissues, it is because it has no blood vessels and its metabolism is slow. This makes the immune response last for a long time, and the cornea lasts for a long time. Is in a sensitive state, so prone to allergic diseases, such as vesicular keratitis.

Endogenous keratitis often occurs in the stroma of the cornea and does not generally cause corneal ulcers.

3. Spread of neighboring organizations

Due to the homology of embryology and anatomical continuity, it spreads to the corneal epithelium. Diseases often come from the conjunctiva, such as severe conjunctivitis with superficial keratitis.

Keratitis clinical manifestations

In addition to paralytic keratitis, most patients with keratitis have strong symptoms of inflammation, such as pain, shame, tearing, and eyelid spasm. Keratitis patients not only have ciliary congestion, but also iris congestion. Severe patients may develop edema in the conjunctiva or even the eyelids.

The symptoms of corneal inflammation caused by different etiologies are also different. Bacterial keratitis has the most rapid onset, the most severe symptoms, and increased secretion and stickiness. Viral keratitis is followed by less secretions, which are watery or mucus-like; fungal Keratitis is the lightest, and sometimes the corneal lesions are already severe, but the patient feels less obvious. Corneal sensation in patients with herpes simplex keratitis may diminish.

Corneal inflammation will inevitably affect vision to a greater or lesser extent, especially if the inflammation invades the pupil area. The corneal scar formed after the ulcer heals not only prevents light from entering the eye, but also changes the curvature and refractive power of the corneal surface, making it impossible for the object to focus on the retina to form a clear object image, and thus reduces vision. The degree of vision involvement depends entirely on the location of the scar. If it is located in the middle of the cornea, even though the scar is small, it affects vision greatly.

Keratitis examination

Slit lamp inspection

Slit lamp microscope can clearly observe the eyelid, cornea, conjunctiva, sclera, iris, and anterior segment of the eye. Keratitis is typically manifested by ciliary congestion, corneal infiltration, and corneal ulcer formation.

2. Corneal confocal microscope

It is an effective method to diagnose fungal keratitis and Acanthamoeba keratitis by confocal laser.

3. Corneal lesion scraping examination

Including smear staining microscopy, pathogenic microorganism culture, and drug sensitivity tests can identify pathogenic bacteria and guide treatment.

4. Corneal tissue biopsy

Tissue biopsy of the corneal lesion area can increase the positive rate of microbial detection, which is applicable when the repeated culture of progressive corneal ulcer is negative.

Keratitis diagnosis

The diagnosis can be confirmed based on medical history, clinical manifestations, eye examination and auxiliary examination. The focus is on clarifying the cause, first of all determining whether it is infectious or non-infectious.

Inquire about medical history in detail, such as history of eye trauma, contact lens wearing history, cold fever history, eye or systemic long-term medication and system-related disease history. During the examination, pay attention to whether there is a decrease in vision, whether there is inflammation in the conjunctiva and iris, the size, shape, and color characteristics of the corneal lesions, the amount and color of the secretions, whether there are corneal perforation signs, whether there is pus in the anterior chamber, and whether there is corneal perception. decline.

Keratitis treatment

The basic principle of treating keratitis is to take all effective measures to quickly control the infection, strive for an early cure, and reduce the sequelae of keratitis to a minimum. Since most ulcerative keratitis is caused by external causes, it is extremely important to eliminate pathogenic microorganisms to remove pathogenic external causes. In addition to ocular treatment, corneal lesions related to systemic diseases should also actively treat the primary disease. During the treatment, pay attention to observation. If the conjunctival congestion is reduced, the corneal lesions are reduced and flattened, indicating that the treatment is effective. If the conjunctival congestion becomes worse, the corneal lesions will expand deeper and surrounding, the anterior chamber pus will be obvious, the surface condition will deteriorate, and the treatment will be ineffective. The treatment plan should be adjusted in time. Conservative treatment is ineffective or scars left by ulcers significantly affect vision for corneal transplantation.

Hot pack

It can make the blood vessels in the eye dilate, relieve stagnation, and at the same time promote blood flow, enhance resistance and nutrition, and make the ulcer recover quickly.

2. rinse

If there are many secretions, the conjunctival sac can be washed 3 times or more daily with normal saline or 3% boric acid solution to flush out secretions, necrotic tissue, bacteria and toxins produced by bacteria. In this way, not only can reduce the factors of infection expansion, but also ensure that the concentration of local drug application will not be reduced.

3. Mydriasis

Enlarging the pupil can reduce iris stimulation, prevent post-iris adhesion, and keep the eye in a resting state, which is conducive to the healing of ulcers. Atropine is a commonly used drug, with a concentration of 0.25% to 2% solution or ointment, which is dripped and applied daily (press the lacrimal sac after dripping to prevent the solution from being excessively absorbed by the mucosa and causing poisoning).

4. Drug treatment

(1) Antimicrobial treatment Select effective drugs for pathogenic microorganisms for local eye drop treatment. For severe corneal ulcers, antibiotics can be injected under the bulbar conjunctiva. For ulcers with severe conditions that are not known for the results of bacterial culture and drug sensitivity tests, multiple broad-spectrum antibiotics can be tried at the beginning.

(2) Glucocorticoid The application of glucocorticoid should be strictly controlled, and it can be used for the treatment of allergic keratitis and keratitis. In the acute phase of bacterial keratitis and fungal keratitis, glucocorticoids are contraindicated.

(3) Oral drugs For severe keratitis, oral drugs can be added to increase local nutrition and promote ulcer healing. Commonly used vitamin C, vitamin B ₂ and cod liver oil pills.

5. Bandaging and dressing

(1) In order to stop the movement of the eyeball and promote the early healing of the ulcer, it must be wrapped. This treatment is particularly suitable for winter. Because it not only prevents the eyeballs from getting cold, but also produces heat and protection.

(2) If there is secretion in the conjunctival sac, it should not be bandaged, and it can be replaced by Buller's eye mask or black glasses. In addition, if the ulcer potential will break through, or it will bulge during the scarring period, daily pressure bandages should be applied. If it is not possible during the day, it should be used during nighttime sleep to save the adverse consequences.