Method and apparatus for placing tear duct drain tubes

A method of putting a two-duct probe into place in the tear ducts using a hollow cylindrical cannula which is closed at its distal end, with an oblong opening being formed in the vicinity of the distal end. A slot extending proximally from the opening allows a narrowed portion of a guide filament attached to each end of a two-duct probe to pass in order to disengage the cannula from the filament. The cannula is removed from the tear duct and the ends of the guide filaments are each pulled into the nose to place the probe into the tear ducts.

The present invention relates to a method of putting a two-duct 
ophthalmological intubation device into place, and to a cannula for 
performing the method. 
BACKGROUND OF THE INVENTION 
Two-duct drainage fixtures are constituted by a fine silicone tube designed 
to be intubed in the tear ducts in order to remedy certain dysfunctions 
such as stenoses that block said duct. The ducts communicate with the eye 
via meatuses located close to the nose in the top and bottom eyelids, and 
their function is to remove tear fluid via the nose. 
It is known that in the event of these ducts being diseased, they can be 
intubed by means of a flexible filament or tube that unblocks the stenoses 
and reestablishes the flow of tear fluid. The problem solved by the 
invention is that of intubing tear ducts. At present, the silicone tube to 
be inserted in the ducts is terminated at each of its ends by a flexible 
metal mandrel that serves as a guide for following a twisting path. The 
drawback of that method of putting the tube into place is that it usually 
leads to bleeding, particularly when bringing the mandrels out into the 
nasal cavity, and in any event it is traumatic. Such a method is described 
in U.S. Pat. No. 4,380,239-Crawford et at. 
The problem can be remedied using the Busse technique in association with a 
Ju/ nemann probe. The Busse technique essentially consists in passing a 
fine filament along the ducts and then in using the filament to pull the 
silicone tube which is of greater diameter. 
A Ju/ nemann probe is in the form of a hollow cannula having fins for 
grasping purposes at its top end and a lateral hole at its bottom end, its 
leading tip being closed. The leading end of the probe is initially 
cathetered in the meatus in a position that is slightly inclined relative 
to the horizontal so as to penetrate into the horizontal portion of the 
duct, after which it is caused to rotate through substantially 90.degree. 
and a fine guide filament, e.g. of prolene, is pushed inside the probe and 
then inside the nasal cavity from which it can be retrieved by means of a 
hook or tweezers. The Ju/ nemann probe is then slid from the other end of 
the filament from which it escapes. This operation is repeated in each of 
the two ducts. After which each of the guide filaments is united to the 
end of the probe proper. 
That technique has the advantage of avoiding bleeding and of being 
non-traumatic. However, compared with the two-duct probes mentioned above 
it requires more time and it is considerably more complex. The length of 
time required is due in particular to the fact that the surgeon must make 
the connection between the prolene filament and the silicone tube after 
extracting the probe. 
The surgeon therefore needs to perform the following operations in 
succession: 
a) inserting the cannula in a tear duct; 
b) pushing the guide filament into the cannula; 
c) pulling the guide filament from inside the nasal cavity; 
d) extracting the cannula from the tear duct and from the filament by 
making it slide upwards along the guide filament; 
e) connecting the guide filament to the silicone tube; 
f) causing the assembly comprising the guide filament and the silicone tube 
to move along the tear duct by pulling from below and pushing from above 
in small successive movements in order to avoid disconnecting the filament 
from the tube; and 
g) once the silicone tube appears in the nasal cavity, separating the 
filament from the tube and pulling thereon. 
After which the same operation needs to be performed in the other meatus. 
The operation which is the most lengthy and the most difficult is step f). 
It is not possible for the surgeon to fix the guide filament to the 
silicone tube in advance since the cannula must be removed from the guide 
filament before the connection can be made. 
OBJECTS AND SUMMARY OF THE INVENTION 
An object of the present invention is to mitigate that drawback and to make 
available to the surgeon a guide filament and silicone tube assembly from 
which the probe can easily be removed, thereby avoiding or facilitating 
steps e), f), and g). 
According to the present invention, the method of putting a two-duct probe 
constituted by a silicone tube into place by means of an intubing cannula 
constituted by a hollow cylindrical body closed at its bottom end whose 
outside diameter is less than the outside diameter of the silicone tube 
that presents a lateral opening close to its leading end consists in: 
providing each of the ends of the silicone tube with a guide filament of 
diameter smaller than the inside diameter of the hollow cylindrical body; 
providing a longitudinal slot inside the hollow cylindrical body and 
extending from the opening to the back end of the body; 
forming a narrow zone in the guide filament, the diameter of the narrow 
zone being slightly less than the width of the slot; 
inserting the cannula in a meatus; 
sliding the guide filament along the duct until it becomes apparent inside 
the nose; and 
causing the cannula to pass over the narrowed portion so as to disengage 
the guide filament. 
It therefore suffices to cause the cannula to slide over the filament until 
the narrower zone comes level with the slot, and then to disengage the 
cannula by causing it to pivot relative to the filament. 
Because of the invention, the connection between the guide filament of 
prolene and the silicone tube can be made in the factory, e.g. by means of 
adhesive (step f) and the surgeon can pull on the guide filament that 
appears in the nose substantially continuously, thereby achieving a 
considerable saving in time (step g).

MORE DETAILED DESCRIPTION 
In FIG. 1, it can be see that the cannula comprises a cylindrical hollow 
body 1 whose front or bottom end 3 is closed. In the vicinity of this end 
there is an oblong hole or opening 2. At the other end of the cannula 
there are fins 4 for grasping purposes. 
According to the invention, a longitudinal slot 5 extends from the opening 
2 along the entire length of the cannula. This slot may be made by 
electroerosion, for example. 
Given anatomical type constraints, the cannula is 0.5 mm in diameter and 
the slot is 0.25 mm wide. The length of the cannula is 100 mm, but that 
dimension is not critical. 
A prolene filament 6 (FIG. 2) is inserted in said cannula, the diameter of 
the filament being 0.4 mm so as to enable it to slide freely inside the 
cannula. As can be seen in FIG. 2, the prolene filament is connected to 
the front end 8 of a silicone tube 2 in which it is a force-fit and 
optionally retained by adhesive. The inside diameter of the tube 9 is 0.3 
mm, and after the filament 6 has been inserted therein its outside 
diameter is 0.64 mm, for example. 
The above-mentioned elements can be seen in FIG. 3. The cannula 1 is 
inserted into the bottom tear duct of an eye O and it penetrates into the 
nasal cavity N. During such insertion, the cannula 1 contains the filament 
6 extending up to its opening 2. After insertion, the filament 6 is pushed 
by means of tweezers (not shown) until its bottom end appears inside the 
nose. Then while holding the filament, the cannula 1 is disengaged from 
the tear duct and caused to slide along the filament 6 until it reaches 
the narrowed zone 7 thereof. Then it is disengaged from the filament 6 by 
a pivoting movement and the filament is pulled down, thereby entraining 
the tube 9 which in turn penetrates bit by bit into the corresponding tear 
duct. 
The same operation is repeated with the second tear duct and the operation 
is completed by ligating the two tube ends 9 inside the nose.