A
watery eye can be the product of excess tear production (hyper-lacrimation),
disturbed ocular surface tear flow (lid malposition) or disturbed outflow
(epiphora). Occasionally all three mechanisms can be involved. Epiphora
is due to some form of compromised drainage which may be caused by:
a) punctal Plimosis, b) canalicular stenosis and obstruction or c) naso-lacrimal
duct blockage. Obstruction of the naso-lacrimal duct may be congenital,
in which case it is most usually due to delayed canalization of the valve
of Hasner, or it may be acquired.
In
adults the commonest cause of epiphora is primary acquired nasolacrimal
duct obstruction (NLDO) which is associated with inflammation of the nasolacrimal
duct.
Epiphora
in the presence of a patent lacrimal system to syringing and in the absence
of excess tear production or lid malposition is defined as functional NLDO.
Management
of less common causes of epiphora such as congenital facial abnormalities
and secondary acquired obstructions am not discussed in this article.
EPIPHORA
IN CHILDREN
Symptomatic
NLDO occurs in approximately 5-6% of infants. A sticky, watery eye with
positive regurgitation on pressure over the lacrimal sac confirms the diagnosis.
Other diagnostic measures such as probing or dacryoscytography (DCG) may
be combined with treatment under general anaesthesia.
As
there is a high spontaneous rate of remission (60-90%) in the first year
of life, probing should be delayed until 10-12 months of age.1, 2 Parents
can be instructed to undertake lacrimal sac massage during the intervening
period. Earlier probing is only justified if their is severe recurrent
infection.
Probing
of the naso-lacrimal duct is the first line of treatments However probe
failure increases with age and is known to double every 6 months.1 For
this reason and in cases of persistent epiphora, a second probing two to
four months later is advocated. In failed cases with persistent epiphora
and recurrent infection, it may be necessary to perform a dacryocystorhinostomy
(DCR). Alternatively bicanalicular silicone incubation with Crawford, Juneman
or Ritleng tubes can be carried out with a claimed success rate of 88-95%.4,5
EPIPHORA
IN ADULTS
Causes
of disturbed ocular surface tear flow such as lid malposition (euryblepharon,
punctal ectropion, punctal phimosis) or ocular surface irritation (dry
eye, blepharitis) should be excluded first.
Identification
of the site of the obstruction causing epiphora is most important, This
information has been shown to dramatically increase the chance of successful
tmatrnent.6
INVESTIGATIONS
Identification
of the site of blockage requires one or more of the following tests:
Dye
tests
Two
or three drops of sodium fluorescein are instilled into the lateral fornix.
Dye may drain completely (dye disappearance) and be collected by a swab
at the inferior meatus (Jones I), when the drainage system is patent. No
more tests are necessary at this stage. With compromised drainage, dye
usually overflows medially onto the cheek. In the presence of lid malpositions
it overflows medially, centrally or laterally, according to the lid position.
The
ocular surface is examined simultaneously. Conjunctival and corneal staining
should be noted to rule out ocular surface disease. On the whole dye tests
are objective and not reliable.
Syringing
and probing
The
lower puncti are gently dilated under topical anaesthesia. Next, one or
two mls of local anaesthesia are injected using a lacrimal canula. If there
is regurgitation, the largest lacrimal probe which can be inserted without
damaging the annulus is used. If it enters the sac without my resistance,
the site of blockage is most probably NLD. If a site of resistance is noted,
the probe is grasped with forceps at the punctum and withdrawn. The exposed
end is measured to identify accurately the site of the blockage. A smaller
sized probe is then inserted. Resistance at the same site reveals a complete
canalicular obstruction. In the case of stenosis the smaller probe can
be passed through and into the sac. Syringing of the NLD then follows.
The same examination is repeated for the upper puncti. An experienced examiner
can gather enough information at this stage to plan treatment.
Macro
dacryocystography (MDCG) and scintigraphy
These
further investigations may be used to confirm the diagnosis. MDCG is particularly
useful to reveal details of lacrimal sac anatomy and the site of nasolacrimal
duct obstruction.8 MDCG with a delayed erect film 5 minutes after injection
of contrast medium can detect functional NLDO by showing delayed clearance
of the lacrimal sac.9 Scintigraphy is mainly used to confirm a diagnosis
of functional blockage when there is delayed or no out- flow of radioactive
media in the presence of a normal DCG.
Canalicular
Endoscopy
More
recent investigative tools are available such as the microcanalicular endoscope,
which can demonstrate the site and type of blockage. However, experienced
lacrimal surgeons can usually gather sufficient information by simply probing
the canaliculi.
TREATMENT
Nasolacrimal
duct blockage
External
DCR is still the most popular choice for NLDO and dacryocystitis and has
a success rate of 80-95%. If there is canalicular damage or a narrow upper
nasal cavity it may be necessary to insert a silicone tube. Day-case external
DCR under local anaesthesia is gaining popularity.
Endonasal
DCR is acknowledged to have a lower success rate.10,11 Power tool and laser
assisted DCR's can be performed as day case procedures and can be less
time consuming.12
Balloon
dilatation dacryoplasty his also been shown to be effective in partial
nasolacrimal duct obstruction with a claimed success rate of 60%.12
Canalicular
obstruction
a)
Canalicular blockage
More
complex surgical procedures are necessary if intubation is not successful.
The micro-surgical repair of canaliculi has been proposed with a canaliculo-DCR
being reserved for distal canalicular blockage. Retrograde intubation of
the canaliculi combined with DCR is used for proximal canalicular obstruction
and punctal agenesis, with a success rate of 60-70%.13 During a standard
DCR the inner opening of the common canaliculus is identified and probed
towards the blocked canaliculi. On reaching the site of the blockage a
pseudo punctum is fashioned. A silicone tube is then inserted through the
same route.
b)
Canalicular stenosis
Silicone
tube insertion during DCR is necessary. Alternatively canaliculoplasty
by closed technique bicanalicular silicone tube insertion can be performed.
A success rate of up to 70% has been reported. 15,16 Early anecdotal reports
indicate that endocanalicular Erbium laser, used prior to intubation, has
an arguably (but as yet unproven) better outcome.
In
cases of failure of the above procedures, a by-pass operation is the only
remaining option. Conjunctivo-DCR with a Lester-Jones tube can be performed
as a closed technique in the presence of a previous osteotomy
Functional
blockage
Functional
blockage due to preductal or ductal narrowing, identified by delayed MDCG
or scintigraphy can be treated by DCR and a silicone stent. Many cases
of functional blockage have also been successfully treated using lid shortening
and punctal snip procedures.16 It seems that in such cases other underlying
causes have been responsible such as punctal phimosis. Functional blockage
due to pump failure (facial nerve palsy) might require by-pass lacrimal
surgery. Treatment remains controversial.
SUMMARY
-
Ocular
surface irritation and lid mal-positions should be addressed initially.
After identification of the site of blockage an appropriate plan of action
should be adopted.
-
Probing
of the canaliculi in experienced hands is an effective diagnostic tool.
-
Partial
canalicular blockage can be treated by either DCR and silicone tube insertion
or by closed technique canaliculoplasty involving bicanalicular insertion
of a stent into the naso-lacrimal duct.
-
Extensive
canalicular blockage requires more complex surgery. Canaliculo-DCR for
distal obstruction and DCR with retrograde intubation for proximal obstruction.
-
Lacrimal
by-pass surgery with a Lester-Jones tube is the last resort when other
techniques have failed to achieve recanalisation of the drainage system.
Bijan
Beigi, Norwich Hospital.
References:
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Focus
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