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Overview
Dacryostenosis, also known as a blocked tear duct,
is a fairly common condition that disrupts normal
tear drainage. It occurs in infants, in older
children, and adults. It is generally not a
serious condition and rarely poses a threat to
vision.
The outer layer of the eye is coated by a
three-layered tear film. The tear film serves
several purposes:
-
Keeps the eyes moist
-
Protects the eyes from infection and irritation
-
Keeps the surface of the eyes smooth so light
can pass through easily
The outermost surface of the tear film is oil
produced by the meibomian gland. Its purpose is to
keep the tear surface smooth and reduce
evaporation of the watery layer beneath it.
Tears, which make up the middle layer, are
produced by the lacrimal cells. Their job is to
cleanse the eye and wash away foreign materials
and irritants. The third layer is mucus
produced by conjunctival goblet cells. Mucus helps
keep the eye moist by allowing the tears to spread
evenly over the eye.
Tears from the surface of the eye normally drain
into the nose through a tube called the
nasolacrimal duct. If this duct is obstructed
or blocked, the tears are unable to properly drain
and overflow onto the cheek. Blockage can be
caused by different factors. In infants, the duct
may be incompletely developed. In most cases,
blocked tear ducts in babies resolve on their own,
usually before the first birthday. Tears are
essential to eye health and function; when
disruption in their production or drainage is
caused by a blockage, treatment is needed to open
the obstruction. In adults and older children,
obstruction may be due to infection, injury, or a
tumor.
Incidence and Prevalence
About 500,000 people in the United States are
affected by dacryostenosis every year. Most cases
are children under the age of 2 and adults over
the age of 50. About 6% of babies are born with a
blocked tear duct (usually in one eye only). The
condition resolves with little or no treatment by
the infant’s first birthday in more than 90% of
cases.
Causes
Although dacryostenosis can occur at any age, it
is most common in infants who have an inborn
obstruction of the nasolacrimal duct. The valve of
Hasner, which is located at the end of the duct,
is the most common place for blockage to occur.
Either the membrane covering the valve in utero
did not dissolve, or the drainage channel is
narrower than normal.
In adults, blockage can be caused by the
following:
-
Enlargement of facial bones near the nose, due
to aging
-
Idiopathic inflammation (i.e., inflammation with
an unknown cause)
-
Infection in the tear duct
-
Nasal polyps
-
Sinus disease
-
Trauma to the eye or nose
-
Tumor
Dacryocystitis
is an infection of the tear sac that may result
from a blocked duct. Because the tears do not
drain normally, bacteria can collect in the ducts
or the tear sac. Dacryocystitis can develop into a
chronic condition and can spread to adjacent
sinuses and into the bloodstream, if the infection
is not treated effectively.
Signs and Symptoms
The primary symptom of a blocked tear duct is
excessive tearing. The tears may overflow onto the
face and run down the cheek. There is often a
mucous discharge as well. This condition may occur
in both eyes.
Infection
is common and may even be the reason for the
blockage. Symptoms of infection include redness or
swelling of the inner corner of the lower lid,
discharge, and tenderness.
Diagnosis
Diagnosis is based on symptoms. The cause of the
tear duct blockage must also be identified. Tests
are determined by the patient’s age and symptoms.
The eye doctor takes a history of past medical and
vision problems and current eye problems and may
perform a basic eye exam.
To determine the presence and extent of tear duct
blockage, a fluorescein eye stain is used
to observe the drainage of tears. An orange dye is
placed in the eye using a dropper or blotting
paper. After it covers the surface of the cornea,
a blue light is shone on the eye to detect
abnormalities on the cornea, including delays in
tear drainage.
An internal examination of the nose may be
indicated, especially if an injury has occurred.
Imaging tests and x-rays also may be warranted to
rule out other causes, such as a tumor. In adults,
a fluid is irrigated through the nasolacrimal
drainage system to locate and determine the extent
of the blockage.
Treatment
Treatment depends on the symptoms, the cause, and
the age of the patient. If an infection is
present, it is treated first. Oral antibiotics are
generally the treatment of choice, but in some
cases, antibiotic eye drops or ointment may be
prescribed. If the infection occurred as a result
of an obstructed duct, other measures are
implemented.
A blocked duct in an infant is treated by gently
massaging the area between the eye and nose
several times a day. This treatment is usually
successful in opening a blockage or helping to
move a blockage that is in the process of
self-resolving. If tearing is persistent beyond 1
year of age or if the affected eye is infected, a
surgical procedure is performed.
In adults, the cause of the blockage must be
determined. If an infection clears and the duct
remains obstructed, or if an infection recurs,
further treatment may be necessary.
In children and adults, a duct can sometimes be
reopened by placing a small probe into the
duct. If this does not remove the obstruction, a
silicone tube can be inserted to maintain an
opening. In children, the tube usually must remain
in position for 6 to 12 months, until the tear
duct stays open by itself. The drawback to this
method is that a second procedure may be necessary
to remove them.
Surgery
If conservative measures fail, patients may
require a procedure called
dacryocystorhinostomy, the creation of a new
passage for tears to flow. This is performed in a
hospital, under general anesthesia. The procedure
is more than 90% successful in relieving the
blockage.
If the tear duct is damaged beyond repair due to
chronic infection or injury, an artificial duct
can be surgically implanted. The artificial tear
duct, called a Jones tube, is placed behind the
inner corner of the eyelid to drain tears into the
nose.
Tumors or nasal polyps that cause obstruction
usually are removed surgically.
Prevention
In many cases, tear duct obstruction cannot be
prevented. Safety precautions should be taken when
playing contact sports and performing other types
of physical activities (e.g., wearing helmets and
face masks) to prevent trauma to the face. Prompt
and adequate treatment for nasal and eye
infections may also reduce the risk. |
