Conjunctivitis is a collective term for the inflammatory reaction of the conjunctival tissue in response to external and the body’s own factors. Although conjunctivitis itself does not have a serious impact on vision, when its inflammation spreads to the cornea or causes complications, it can lead to visual impairment. According to the condition and course of conjunctivitis, it can be divided into acute, subacute and chronic; according to the etiology, it can be divided into bacterial, viral, chlamydial, fungal and allergic; according to the characteristics of conjunctival lesions, it can be divided into acute follicular conjunctivitis, chronic follicular conjunctivitis, membranous and pseudomembranous conjunctivitis, etc.
Etiology
The etiology of conjunctivitis can be divided into two categories, infectious and non-infectious, according to its different nature.
1. Infectious. Inflammation of the conjunctiva due to infection by pathogenic microorganisms.
2. Non-infectious. Allergic inflammation caused by local or systemic allergic reactions is the most common. External physical and chemical factors, such as light and various chemicals, can also be causative factors.
Clinical manifestations
Conjunctival congestion and increased secretion are common features of all types of conjunctivitis, and inflammation may occur in one or both eyes simultaneously/sequentially.
1. Symptoms
Foreign body sensation, burning sensation, heavy eyelids, increased secretions, photophobia, lacrimation and varying degrees of visual acuity loss when the lesion involves the cornea.
2.Signs
Signs of conjunctivitis are an important basis for the correct diagnosis of different types of conjunctivitis.
(1) Conjunctival congestion Conjunctival vascular congestion is characterized by more pronounced congestion near the dome, with a reticular distribution of blood vessels and bright red color, which may extend into the periphery of the cornea to form a corneal vascular opacity, which disappears soon after epinephrine is applied.
(2) Discharge Purulent discharge is mostly seen in gonococcal conjunctivitis; mucosal purulent or cicatricial discharge is mostly seen in bacterial or chlamydial conjunctivitis, which often sticks firmly to the eyelashes and makes it difficult to open the eyelids in the morning; aqueous discharge is usually seen in viral conjunctivitis.
(3) Conjunctival edema Conjunctival inflammation causes conjunctival vasodilatation and exudation resulting in tissue edema, which is evident in edema due to relaxation of the bulbar conjunctiva and vaulted conjunctival tissue.
(4) Subconjunctival hemorrhage Mostly punctate or small flakes, epidemic hemorrhagic conjunctivitis due to virus can often be accompanied by subconjunctival hemorrhage.
(5) Papillae are nonspecific signs of conjunctival inflammation and can be located on the lid conjunctiva or corneal limbus, presenting as a raised polygonal mosaic-like appearance with areas of congestion separated by pale sulci.
(6) Follicles Follicles are yellowish-white, smooth, round elevations, 0.5 to 2.0 mm in diameter, but in some cases such as chlamydial conjunctivitis, larger follicles may also be present; viral and chlamydial conjunctivitis are often referred to as acute follicular conjunctivitis or chronic follicular conjunctivitis because of the concomitant marked follicle formation.
(7) Membrane and pseudomembrane Membrane is attached to the surface of the conjunctiva fibrin exudate, pseudomembrane is easy to peel off, while the true membrane is not easy to separate, the wound bleeding after forced peeling, the essential difference between the two is the difference in the degree of inflammatory response, the true membrane inflammatory response is more intense, diphtheria bacilli cause severe membranous conjunctivitis; β-hemolytic streptococcus, pneumoniae, gonococcus, adenovirus, inclusion bodies, etc. can cause membranous or pseudomembranous conjunctivitis.
(8) Scarring Damage to the stromal tissue is the histological basis for conjunctival scar formation. Early conjunctival scarring is manifested by narrowing of the conjunctival dome and subepithelial fibrosis of the conjunctiva.
(9) Preauricular lymph node enlargement Viral conjunctivitis is often associated with preauricular lymph node enlargement.
(10) Pseudohyperlidosis Mild ptosis due to hypertrophy of the upper lid tissue by cellular infiltration or scar formation, most often seen in the late stages of trachoma.
(11) Conjunctival granuloma Less common, seen in chronic inflammation caused by tuberculosis, leprosy, syphilis, and rickettsiae.
Examination
1.Conjunctival scraping
Gram stain and Kimsa stain initially determine the type of pathogenic bacteria and the characteristics of the inflammatory response of the conjunctiva. If the infiltration of neutrophils is predominant, it often suggests bacterial or chlamydial infection; if mononuclear cells increase or multinucleated giant cells appear, it may be viral infection; if there are inclusion bodies in the cytoplasm of epithelial cells and lymphocytes and plasma cells, it suggests chlamydial infection.
2, bacteriological examination of the conjunctiva, bacterial culture of secretions and drug sensitivity test
These tests help in the diagnosis of pathogenesis and guide treatment. If chlamydia or viral infection is considered, laboratory pathogen isolation or application of PCR techniques can be done to help in the diagnosis.
Diagnosis
The first step is to make a preliminary diagnosis based on the patient’s pathogenesis and clinical manifestations, e.g., infectious conjunctivitis usually develops in both eyes and can involve family members; most acute viral conjunctivitis develops first in one eye and then in the other; trachoma is predominantly upper lid lesions; whereas acute follicular conjunctivitis due to viruses is predominantly lower lid; bacterial conjunctivitis is more Bacterial conjunctivitis has more pronounced cicatricial symptoms; gonococcal inflammation has a large amount of purulent discharge; all of these lesion characteristics help in the diagnosis.
Treatment
1.Local treatment
(1) rinse the conjunctival sac The role is mainly clean, commonly used for saline, 2% to 3% shed acid solution or 1: 5000 ~ 1: 10000 liters of mercury (or potassium permanganate) solution.
(2) Do not cover the affected eye Because there are many secretions in conjunctivitis, if the affected eye is covered, the secretions are not easily discharged and are stored in the conjunctival sac; and the temperature of the conjunctival sac will rise after covering, which is more conducive to the reproduction of bacteria and makes conjunctivitis worse.
(3) Local medication Antibacterial drugs or antiviral eye drops According to the pathogenic diagnosis, choose the appropriate therapeutic drugs. Commonly used 0.5% to 1% silver nitrate, when dropping the eye, turn the eyelid and put the drops on the lid conjunctiva, stop for a moment after dropping the eye, that is, rinse with saline. Or dip a cotton swab into a small amount of the solution, apply it to the surface of the lid conjunctiva, and then rinse with saline.
2. Systemic treatment
For severe conjunctivitis, such as gonococcal conjunctivitis and trachoma, a combination of systemic medication is required.
Prevention
Conjunctivitis is mostly contagious by contact, so you should promote diligent hand washing and avoid rubbing your eyes at will. Promote running water to wash the face, towels, handkerchiefs and other items should be separated from others, and often cleaned and disinfected. Certain isolation measures should be taken for patients with infectious conjunctivitis, and swimming in public swimming areas should not be allowed. If one eye has conjunctivitis, the patient must be told to protect the healthy eye from infection. Anyone who works in an environment stimulated by wind, dust and smoke should improve the environment and wear protective glasses to prevent conjunctivitis.