Patent Application
20070208362
1. Field of the Invention
The present invention relates to a medical device that is used to cut a cornea.
2. Background Information
There have been developed a number of different surgical techniques to correct hyperopic or myopic conditions of a human eye. U.S. Pat. No. 4,840,175 issued to Peyman discloses a procedure wherein a thin layer of a cornea is cut to expose the stroma layer of the cornea. A laser beam is then directed onto the exposed corneal tissue in a predetermined pattern. The laser beam ablates corneal tissue and changes the curvature of the eye. This procedure is sometimes referred to as Laser in situ Keratomileusis (LASIK).
U.S. Pat. No. Re 35,421 issued to Ruiz et al. discloses a device for cutting a cornea in a LASIK procedure. Such a device is commonly referred to as a microkeratome. The Ruiz microkeratome includes a ring that is placed onto a cornea and a blade that is located within an opening of the ring. The device also contains a drive mechanism which moves the blade across the cornea in a first direction while the blade moves in a reciprocating transverse direction to cut the eye. The device can create a lamella flap of the cornea which is flipped back so that the stromal bed of the cornea can be ablated with a laser.
U.S. Pat. No. 6,051,009 issued to Hellenkamp et al. discloses a microkeratome that is sold under the trademark HANSATOME. The HANSATOME microkeratome moves the blade in an arcuate path about the cornea. The HANSATOME includes a disposable blade assembly that can be loaded and removed from the device. The blade assembly includes a blade holder that is attached to a cutting blade. The blade holder has a recess that receives the end of a drive shaft. Rotation of the output shaft moves the blade in an arcuate path, and moves the blade in a back and forth motion to create the lamella flap of the cornea.
Microkeratomes have three primary components, a hand piece that contains a motor, a head that holds the blade, and a ring that applies a suction to maintain the position of the microkeratome relative to the cornea. Because the microkeratome is in contact with patient tissue it must be cleaned after each procedure, typically in an autoclave. The motor and accompanying gears are typically enclosed by a housing of the hand piece. The enclosed nature of the assembly increases the difficulty of cleaning the internal components of the hand piece. Additionally, the autoclave process may degrade the hand piece motor after a number of procedures and cleaning cycles. It would be desirable to provide a microkeratome that does not require the hand piece to be sterilized after each surgical procedure.
The blades used to cut tissue are replaced after each procedure. The replacement blades are typically loaded into the head of the microkeratome with a pair of tweezers. The blade must be loaded accurately so that a drive pin of the motor assembly is inserted into a corresponding slot of a blade holder. Accurately loading the blade with tweezers can be a time consuming process. It would be desirable to provide a blade package that can be used to accurately load a blade into a microkeratome in a time efficient manner.
A complication may occur while the microkeratome is cutting the lamella flap. It may be desirable to remove the microkeratome in the middle of a cut. Removing the microkeratome requires releasing the vacuum of the suction ring. Releasing the vacuum allows the cornea to move back to its original shape. Movement of the cornea will also cause the blade to move. Movement of the blade may cause damage to the cornea. It would be desirable to provide a microkeratome that allows a surgeon to remove a blade while the suction ring is still fixed to the cornea. It would also be desirable to provide a microkeratome that allows the surgeon to vary the thickness of the lamella flap hinge. cl BRIEF SUMMARY OF THE INVENTION
A microkeratome that has a head coupled to a hand piece by a latch assembly. The head holds a blade.
Disclosed is a microkeratome that includes a latch assembly that couples a head to a hand piece. The latch assembly allows the head to be readily detached from the hand piece and sterilized. There is no need to also sterilize the hand piece. The microkeratome also has a ring assembly that is coupled to the head and the hand piece. The ring assembly may include a fastener that can be unfastened to allow the hand piece and head to be detached from the ring, even while the ring assembly is fixed to a cornea.
The hand piece includes a motor that moves the blade across the ring. The microkeratome may have an aspiration connector with a collar that limits the travel of the blade and the thickness of a resulting lamella flap. The aspiration connector can be replaced with a collar of a different diameter to produce a flap with a different thickness. This allows a surgeon to select a flap hinge thickness.
The blade may be loaded into the microkeratome with a blade shuttle. The blade shuttle may have a plunger that pushes the blade into the microkeratome head. The movement of the plunger may be limited by a stop within the shuttle. The stop assist in accurately locating the blade within the head.
Referring to the drawings more particularly by reference numbers,
The head 14 has a blade cavity 20 that can receive a blade (not shown). The ring assembly 16 may include a helical gear 22 that is coupled to the hand piece 12. The hand piece 12 includes a motor (not shown) that cooperates with the helical gear 22 to move the head 14 and blade across an opening 24 of the ring assembly 16. The hand piece 12 may contain another motor (not shown) that moves the blade in a lateral reciprocating manner so that the blade cuts corneal tissue and creates a lamella flap. The head 14 and ring assembly 16 may have tongues 26 and grooves 28, respectively, that create linear bearings.
The ring assembly 16 may include a nut 30 that is attached to the helical gear 22. The nut 30 can be removed to allow the hand piece 12 and head 14 to be detached from the ring assembly 16. This allows the hand piece 12, head 14 and blade to be removed even while the ring 16 is applying suction to a cornea. By way of example, the microkeratome 10 may be actuated to initiate cutting of a cornea by the blade. A complication may occur which causes the surgeon to de-actuate the microkeratome and stop the cutting process. Under suction the ring flattens out the cornea. If the suction is removed the cornea may move back to its natural shape. This movement may cause undesirable movement between the blade and corneal tissue. The nut 30 allows the hand piece 12, head 14 and the blade to be removed from the cornea without removing the suction of the ring 16.
The ring assembly 16 may include an aspiration connector 32. The aspiration connector 32 is connected to an aspiration tube (not shown) and is coupled to aspiration openings (not shown) in the ring. The aspiration connector 32 may have a collar 34 that limits the travel of the head 14 and the blade. The aspiration connector 32 may have a threaded shaft (not shown) that screws into a corresponding threaded opening (not shown) of the ring assembly 16.
Alternatively, the helical gear 22 can provide a stop function. The stop function may be provided by the end of the threads near the fasterner 30. The stop function could also be provided by a nut attached to the threads of the gear 22. The size of the flap hinge can be varied by changing gears 22.
The latch assembly 40 may further have an actuator 48 that can be depressed by a user to move in a downward direction as indicated by the arrow to rotate the latch out of the groove 44. The assembly 40 may include a return spring(s) 50 to move the actuator 48 back when released by the user. As shown in
A user can attach the head 14 to the hand piece 12 by moving the head 14 until the latch 42 snaps into the groove 44. The head 14 can be removed from the hand piece 12 by depressing the actuator 48 to pull the latch 42 out of the groove 44. The head 14 then be sterilized and re-attached to the hand piece 12. Alternatively, the head 14 may be replaced. By way of example, the head 14 may be constructed from a low cost plastic material that is replaced after every procedure. The hand piece 12 may also be constructed from a plastic material. The head may be constructed from the same plastic material as the hand piece. By way of example, the plastic may be a polycarbonate or polysulphone.
As shown in
While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.
