Swelling of conjunctiva and watering of the eyes are symptoms common to all forms of conjunctivitis. However, the pupils should be normally reactive, and the visual acuity normal. Viral Viral conjunctivitis is often associated with an infection of the upper respiratory tract, a common cold, and/or a sore throat. Its symptoms include excessive watering and itching. The infection usually begins with one eye, but may spread easily to the other.
Viral conjunctivitis shows a fine, diffuse pinkness of the conjunctiva, which is easily mistaken for the ciliary infection of Iris (Iritis), but there are usually corroborative signs on microscopy, particularly numerous lymphoid follicles on the tarsal conjunctiva, and sometimes a punctate keratitis. Some other viruses that can infect the eye include Herpes simplex virus and Varicella zoster. Allergic An eye with allergic conjunctivitisAllergic conjunctivitis is inflammation of the conjunctiva (the membrane covering the white part of the eye) due to allergy. Allergens differ among patients. If this is combined with rhinitis, the condition is termed “allergic rhinoconjunctivitis”.
The symptoms are due to release of histamine and other active substances by mast cells, which stimulate dilation of blood vessels, irritate nerve endings, and increase secretion of tears. Bacterial An eye with bacterial conjunctivitis Bacterial conjunctivitis causes the rapid onset of conjunctival redness, swelling of the eyelid, and mucopurulent discharge.
Typically, symptoms develop first in one eye, but may spread to the other eye within 2–5 days. Bacterial conjunctivitis due to common pyogenic (pus-producing) bacteria causes marked grittiness/irritation and a stringy, opaque, greyish or yellowish mucopurulent discharge that may cause the lids to stick together, especially after sleep.
Severe crusting of the infected eye and the surrounding skin may also occur. The gritty and/or scratchy feeling is sometimes localized enough for patients to insist they must have a foreign body in the eye. The more acute pyogenic infections can be painful.  Common bacteria responsible for non-acute bacterial conjunctivitis are Staphylococci and Streptococci. Bacteria such as Chlamydia trachomatis or Moraxella can cause a non-exudative but persistent conjunctivitis without much redness.
Bacterial conjunctivitis may cause the production of membranes or pseudomembranes that cover the conjunctiva. Pseudomembranes consist of a combination of inflammatory cells and exudates, and are loosely adherent to the conjunctiva, while true membranes are more tightly adherent and cannot be easily peeled away. Cases of bacterial conjunctivitis that involve the production of membranes or pseudomembranes are associated with Neisseria gonorrhoeae, ? -hemolytic streptococci, and C. diphtheriae. Corynebacterium diphtheriae causes membrane formation in conjunctiva of non-immunized children.
Chemical Chemical eye injury is due to either an acidic or alkali substance getting in the eye. Alkalis are typically worse than acidic burns. Mild burns will produce conjunctivitis, while more severe burns may cause the cornea to turn white. Litmus paper is an easy way to rule out the diagnosis by verifying that the pH is within the normal range of 7. 0—7. 2. Large volumes of irrigation is the treatment of choice and should continue until the pH is 6—8. Local anaesthetic eye drops can be used to decrease the pain.
Irritant or toxic conjunctivitis show primarily marked redness. If due to splash injury, it is often present in only the lower conjunctival sac. With some chemicals, above all with caustic alkalis such as sodium hydroxide, there may be necrosis of the conjunctiva with a deceptively white eye due to vascular closure, followed by sloughing of the dead epithelium. This is likely to be associated with 1 / 2 slit-lamp evidence of anterior uveitis. Causes Conjunctivitis when caused by an infection is most commonly caused by a viral infection.
Bacterial infections, allergies, other irritants and dryness are also common causes. Both bacterial and viral infections are contagious and passed from person to person, but can also spread through contaminated objects or water. The most common cause of viral conjunctivitis is adenoviruses. Herpetic keratoconjunctivitis (caused by herpes simplex viruses) can be serious and requires treatment with acyclovir. Acute hemorrhagic conjunctivitis is a highly contagious disease caused by one of two enteroviruses, Enterovirus 70 and Coxsackievirus A24. These were first identified in an outbreak in Ghana in 1969, and have spread worldwide since then, causing several epidemics.
The most common causes of acute bacterial conjunctivitis are Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenza. Though very rare, hyperacute cases are usually caused by Neisseria gonorrhoeae or N. meningitidis. Chronic cases of bacterial conjunctivitis are those lasting longer than 3 weeks, and are typically caused by Staphylococcus aureus, Moraxella lacunata, or gram-negative enteric flora. Conjunctivitis may also be caused by allergens such as pollen, perfumes, cosmetics, smoke, dust mites, Balsam of Peru, and eye drops Neotrombicula autumnalis (trombiculid mite) in contact with the upper eyelid margin, inducing conjunctivitis.
An exceptional case of conjunctivitis induced by a trombiculid mite (Neotrombicula autumnalis) was reported in 2013. Conjunctivitis is part of the triad for Reiter’s syndrome, a manifestation of reactive arthritis, which is thought to be caused by autoimmune cross-reactivity following certain bacterial infections. Reactive arthritis is highly associated with HLA-B27.
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