Page 1219 - Problem-Based Feline Medicine

59 – THE CAT WITH OCULAR DISCHARGE OR CHANGED CONJUNCTIVAL APPEARANCE 1211

– Dental disease is the most common cause of
INTRODUCTION
orbital inflammation.
– Orbital neoplasia, particularly lymphosarcoma,
MECHANISM? is another disease that may cause exophthalmos
and chemosis.
Ocular discharge is a sign that the eye is irritated,
– Orbital disease may also be caused by an exten-
inflamed or there is an obstruction to tear drainage.
sion of chronic sinus and nasal inflammation
Ocular discharges vary in type.
or neoplasia, where the bony orbit has been
● A serous (watery) discharge is present when there
breached adjacent to the frontal sinus or poste-
is excess tear stimulation. Excessive tearing is
rior nasal cavity.
known as “epiphora”.
● A mucoid (jelly-like) discharge is seen when the Changed appearance of the conjunctiva is seen clin-
conjunctiva is inflamed and the conjunctival goblet ically as:
cells produce excess mucus secretion. ● Ocular discharge, which may be serous, mucoid or
● A mucopurulent (pus) discharge is found when mucopurulent.
the conjunctiva is inflamed, and there is a mixture ● Chemosis (edema), which causes the conjunctiva to
of mucus secretion and inflammatory cells. swell and bulge under the eyelids.
● Hyperemia (redness) can be intense as the con-
Common causes of ocular discharge include diseases
junctiva has a rich blood supply.
affecting the conjunctiva, cornea, eyelid, orbit or
● Follicle formation occurs because the conjunctiva
tear duct.
is very rich in lymphoid tissue. Antigenic stimula-
● Diseases affecting the conjunctiva include:
tion in chronic inflammation or allergic states is the
– Infectious diseases are the most common causes
most common cause of follicle formation.
of ocular discharge.
● Hemorrhage.
– Allergic conditions.
– Echymoses (focal hemorrhage) and petechia (pin
● Problems associated with the cornea include:
point hemorrhages) may be a sign of a bleeding
– Ulcerative keratitis (inflammation of the cornea).
disorder associated with a systemic disease caus-
– Infectious agents causing keratitis.
ing thrombo-cytopenia.
– Traumatic keratitis.
– Coagulopathies may show signs of conjunctival
● Obstruction to tear drainage.
hemorrhage.
– In cats symblepharon (adhesion of conjunctiva
– Sub-conjunctival hemorrhage is seen in cases of
to conjunctiva or conjunctiva to cornea) is the
trauma.
most common cause of puncta occlusion.
● Peri-ocular pruritis (skin irritation) may be a sign
● Eyelid problems causing irritation of the cornea
of underlying conjunctival irritation.45
include:
● Emphysema (accumulation of air within tissue) of
– Eyelid agenesis (coloboma) is the term used
the conjunctiva may be seen as a rare entity after
when there is a congenital absence of all or part
facial trauma, when air leaks under the skin and
of the normal eyelid margin. It causes trichiasis
conjunctiva to produce swelling that may be con-
(normal eyelid or facial hair irritating the con-
fused with chemosis. Crepitus (a crackling feeling
junctiva or cornea) and exposure and drying of
of the tissue) will be present to help differentiate
the adjacent conjunctiva and cornea.
this from chemosis.
– Eyelid trauma may cause trichiasis because the
eyelid margin is damaged or missing.
– Eyelid neoplasia may cause irritation of the
WHERE?
corneal surface.
● Orbital inflammation (retrobulbar disease) may History and physical examination will help deter-
cause chemosis (conjunctival edema) and ocular mine the cause of ocular discharge, and changed con-
discharge. The eye may show exophthalmos junctival appearance. It is important to determine
(bulging outwards). whether it is an acute or chronic problem.