EYELID ABNORMALITIES:
Common problems of cats & dogs
UPPER AND LOWER EYELID
The upper and lower eyelids have many functions. They protect the cornea
[clear portion out front of the eye] and the eye itself from drying out, from
insults and trauma from the outside. They spread the tears (tear film) across
the cornea. They produce portions of the tear film from glands along the eyelid
margin and from cells in the folds of the eyelids. They determine the shape and
size of the eyelid openings. They keep out the light. Finally they pump the
tears out to the tear duct. Meanwhile, the third eyelid helps to spread the tear
film and produces from 30-to-60 % of the watery portion of the tears.
The eyelids of dogs and cats open between 10 and 14 days of age. If the
eyelids open too early, tear production is not present and signs of
dry eye (keratoconjunctivitis sicca) will occur unless
you apply antibiotic ointment 3-to-4 times daily until tear production begins.
A condition known as
conjunctivitis neonatorum occurs when bacteria or viruses enter the eye
through the eyelids that are closed following birth in dogs and cats. Corneal
rupture and chronic scarring of the cornea and the white of the eye
(conjunctiva) will occur unless the eyelids are opened by a veterinarian and the
eyes are treated with appropriate medication. We now know that in kittens,
conjunctivitis neonatorum is due to herpesvirus infection.
These kitties will benefit from appropriate antiviral medication. Cortisone medication should not be used in these patients.
A lack of portions of the eyelid occurs in cats and is known as eyelid
agenesis oreyelid coloboma. This condition is seen in the lateral
portion of the upper eyelid. This condition will lead to scarring and blood
vessels occurring in the cornea because tears are not spread normally and
because hairs on the 'eyebrow' will rub the cornea. Surgery is necessary to
correct this condition.
An abnormality known as dermoids can occur along the conjunctiva
(white of the eye) on the upper eyelid or along the lateral eyelid opening.
Dermoids are normal skin tissue at an abnormal spot. Depending on the size and
location, these growths may be left alone [if they are causing no problems] or
removed during surgery.
Eyelash disease is actually a group of conditions that
cause eye injury from hairs that irritate the eye. Trichiasis is a
condition of normal hairs lying on or irritating the globe. Examples of this
would be very long facial hairs in long haired dogs and nasal folds in the
Pekingese. Also tiny hairs at the nose side of the eye can act as a wick and
cause tear spilling in Miniature Poodles and Persian cats. Distichiasis
is the condition of an eyelash coming out of an abnormal position in the glands
that are located along the eyelid edge. Districhiasis is more than 1
eyelash coming out of each of the gland openings. Ectopic cilia are
abnormal hairs that exit a hair follicle on the inside of the eyelid. Ectopic
cilia are very painful. The successful elimination of the offending hairs will
require surgical freezing. Excessive facial folds are seen in the newborn Shar
Pei at the time of eyelid opening. The most common treatment is the use of
'temporary tacking' using either sutures or staples to hold the eyelids away
from the cornea to prevent damage.
Lagophthalmos means 'rabbit eye' and is commonly seen in the
Pekingese, Pug, Boston terrier, Lhasa Apso, Japanese Chin, Dandy
Dinmont and Shih Tzu, and the Persian,
Burmese, Exotic Shorthair and Himalayan breeds of
cat. Whilst these animals may not exhibit any signs of eye problems for years,
increased pigmentation will start on the cornea at the nose side of the eye. An
all too common presentation will be the patient that develops a corneal ulcer in
the center of the eye. Lagophthalmos usually requires surgery to prevent further
damage that can cause the eye to rupture.
Entropion (rolling in of the eyelids) and ectropion (rolling
out of the eyelids) are conditions caused by abnormal eyelid position in
relation to the globe itself. If the patient has heavy facial features, they
will probably have ectropion. Only if it causes exposure problems will ectropion
need correction. If the eye size is relatively small for the size of the orbit,
entropion will result. Entropion will often cause abrasions of the cornea and/or
irritation of the conjunctiva. This is very painful and almost always requires
surgery to correct. Entropion or ectropion may occur due to scarring from
previous injury or surgery.
Acquired conditions include: Eyelid neoplasm.
Research has shown that in dogs, approximately 75% are
benign (do not spread). That does mean that 25% are malignant (do spread) and
therefore, all removed masses should be submitted for pathologic examination. In
cats, the ratio of benign to malignant tumors is exactly reversed so that 75%
are malignant. Chalazia are firm, swollen masses that are well
localized. They are removed surgically and pathology should rule-out the
possibility of neoplasm. Eyelid lacerations are injuries that should be
sutured as soon as the patient's stability permits.
Facial nerve palsy (paralysis of eyelids) is commonly seen in patients
with chronic ear infections [American Cocker Spaniels]. Because of the
paralysis of the muscle that circles the eye, the eyelids cannot blink and the
cornea will dry out due to an uneven spreading of the tears. This drying can
lead to ulcers, infection and even globe rupture. Medication alone may help
although surgery may be needed to save the eye! Eyelid inflammation is known as
blepharitis. This is often seen as enlargements of the glands of the
eyelids that will appear as small abscesses on the globe surface of the eyelid.
Gland contents may be expressed by the ophthalmologist and the contents
cultured. Treatment will involve broad-spectrum antibiotics and cortisone given
by mouth, topically applied antibiotics and warm, moist compresses.
THIRD EYELID OR 'HAW'
The gland of the third eyelid may become everted. The exposure to the air
will cause the gland to become red and the condition is called cherry eye.
Because the gland produces 30-to-60% of the tears, it should not be removed.
Surgery should be performed to replace the gland and thus preserve its function.
Occasionally in young patients, the third eyelid will become folded causing
a 'funny' look to the eye (everted third eyelid). This folding often
leads to excessive tearing. This eversion is irritating to the patient and
should be corrected surgically.
As with the eyelids, lacerations and neoplasms may occur to the third
eyelid. They should be treated the same as similar conditions of the upper and
lower eyelids.
Eyelid conditions are often irritating to our pets. With proper treatment,
surgery and medication, further worsening of the condition can be prevented.
Have any questions on this subject? Contact
Dennis Hacker via E-mail:
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Cerrito, CA. * All Rights Reserved
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