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 onmicroscopy, 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

1. BY SHAFIYA

2.  Conjunctivitis (also called pink eye in North
America or Madras eye in India) is inflammation
of the conjunctiva (the outermost layer of the eye
and the inner surface of the eyelids). It is
commonly due to an infection (usually viral, but
sometimes bacterial) or an allergic reaction

3.  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.

4. • 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 onmicroscopy,
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

5. • Allergic conjunctivitis is inflammation of the conjunctiva
(the membrane covering the white part of the eye) due to
allergy.Allergensdiffer among patients. Symptoms consist
of redness (mainly due to vasodilation of the peripheral
small blood vessels), oedema (swelling) of the conjunctiva
, itching, and increased lacrimation (production of tears). 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

6. • 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 areStaphylococci and Streptococci

7. • 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, β-hemolytic
streptococci, and C. diphtheriae. Corynebacterium diphtheriae
causes membrane formation in conjunctiva of non-immunized
children

8. BACTERIAL ALLERGIC

9. • Inclusion conjunctivitis of the newborn (ICN) is a
conjunctivitis that may be caused by the bacteria
Chlamydia trachomatis, and may lead to acute,
purulent conjunctivitis.[13] However, it is usually self-healing.
• Conjunctivitis is identified by irritation and redness of
the conjunctiva. Except in obvious pyogenic or
toxic/chemical conjunctivitis, a slit lamp
(biomicroscope) is needed to have any confidence in
the diagnosis. Examination of the tarsal conjunctiva is
usually more diagnostic than the bulbar conjunctiva.

10. • Conjunctivitis when caused by an infection is most commonly caused by a viral
infection.[14] 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.[15]
Herpetic keratoconjunctivitis (caused by herpes simplex viruses) can be serious
and requires treatment withacyclovir. 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.[16]
• The most common causes of acute bacterial conjunctivitis are
Staphylococcus aureus, Streptococcus pneumoniae, and
Haemophilus influenzae.[15] 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.

11.  Conjunctivitis may also be caused by allergens such as
pollen, perfumes, cosmetics, smoke, dust mites,
Balsam of Peru,[5] 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.

12.  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.

13. • Cultures are taken infrequently, because most cases of conjunctivitis
are treated empirically and (eventually) successfully, but often only after
running the gamut of the common possibilities. Swabs for
bacterial culture are necessary if the history and signs suggest bacterial
conjunctivitis, but there is no response to topical antibiotics. Viral culture
may be appropriate in epidemic case clusters.
• A patch test is used to identify the causative allergen in the case where
conjunctivitis is caused by allergy.[7]
• Conjunctival scrapes for cytology can be useful in detecting chlamydial
and fungal infections, allergy, and dysplasia, but are rarely done
because of the cost and the general lack of laboratory staff experienced
in handling ocular specimens. Conjunctival incisional biopsy is
occasionally done when granulomatous diseases (e.g., sarcoidosis)
or dysplasia are suspected.