Surgery – Instruments – Stereotaxic device
Reexamination Certificate
1998-10-16
2001-07-24
Philogene, Pedro (Department: 3732)
Surgery
Instruments
Stereotaxic device
C600S104000
Reexamination Certificate
active
06264665
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to ultra fine surgery, in particular to surgery apparatus to assist an ocular surgeon in delicate ocular ultramicrosurgical operations, typically on or near retinal tissue, the optic nerve and the anterior chamber.
BACKGROUND OF THE INVENTION
The retina is a very small tissue lining the back inside surface of the eye. It is only 0.25 to 0.3 mm thick but 15 sq cm in area. In western countries, disease of the retina is the main cause of untreatable blindness. There is a vital need to be able to deliver biological treatments or operations to precisely determined retina locations and at specific depths, such as into blood vessels or to particular cells of the retina with a precision better than 5 microns. Currently there is no way such biological treatments or operations can be achieved with such accuracy, thus hindering specific drug and other treatments of the retina. The alternative of delivering drugs through the systemic circulation is not possible when only a small region of the retina is targeted, and delivery of powerful drugs into the ocular contents rather than at a particular location in the retina can have unwanted effects.
Current ocular ultramicrosurgical operations, where it is sought to perform delicate manipulations on areas of tissue as small as a few microns in diameter, have had a limited success rate due to the inability of surgeons to accurately control surgical tools using manual manipulations under the microscope. Even the steadiest hand has an unavoidable physiological tremor which at rest has an amplitude of about 50 micrometers and a frequency of between 7 and 12 cycles per second. After 30 minutes of activity, this physiological tremor increases to an amplitude of 2 to 5 mm at a frequency between 4 and 6 cycles per second.
In ocular research laboratories, retinal arterial or venous occlusion has been treated (mainly in animals) by in vivo cannulation of the vessel and injection of clot-clearing agents such as tissue plasminogen activator (tPA), [ Allf and de Juan Jr 1987]), but application of the technique in routine surgery on humans has been prevented by the very low success rate of such operations, typically 20 percent or lower. The low success rate is due in the case of arterial or vein occlusions to the damage done by the surgeon to the blood vessel when micro cannulation is attempted, the micro cannulation device being relatively substantial (typically 20 to 50 microns) compared with the size of the blood vessel (typically about 100 microns).
Hunter et al [ Hunter et al 1994] have described a sophisticated teleoperated microsurgical robot adapted to automation of corneal and lens operations. This system is not adapted to automation of ultramicrosurgical retinal operation.
Manual systems which assist the eye surgeon, particularly in animal experimentation, have been known for a number of years and incorporate stereotactic systems to support surgical tools such as micropipettes in a manner such that the tool shaft is orientated about a pivot point coincident with the point of entry of the tool into the ocular cavity at the pars plana. [ Toth et al 1992, Benner et al 1993]. Such systems do not completely isolate the physiological tremor from the tip of the surgical tool, and since they are manual in nature result in time consuming operations, reducing the practicality of routine application to human surgery.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a system for ocular ultramicrosurgery which isolates the hands of a surgeon from the patient and provides increased positioning accuracy and speed to make practical the routine application of ultramicrosurgical operations to the eye.
According to the present invention there is provided a system for ocular ultramicrosurgery comprising:
means for immobilising an eye of a patient on which ultramicrosurgery is to be performed;
means for marking the position of a predetermined point on said eye;
tool support and positioning means for supporting a tool in a manner so that said tool can be moved with positional accuracy; and,
remote control means for remotely controlling the position and operation of said tool, said remote control means physically isolating the hands of a surgeon from said tool;
whereby, in use, a surgeon can, by means of said remote control means, position a tip of said tool to enter said eye at said predetermined point and to pivot said tool about said predetermined point so that the tip of the tool can be positioned at any desired location within the eye and subsequently operated to perform ultramicrosurgery.
Preferably said means marking the position of a predetermined point comprises means for defining a point in space.
Preferably said system further comprises means for moving said eye and said point in space relative to each other so that said point in space can be bought to coincide with said predetermined point.
Preferably said means for defining said point in space comprises at least two lasers supported in different planes and arranged so that their respective laser beams intersect in space, said point in space being the point of intersection of said laser beams.
Preferably said means for moving said eye and said point in space relative to each other comprises head fixing means for fixing the position of a head of the patient and, means for moving said head fixing means in three orthogonal planes under control of said remote control means.
Preferably said tool support and positioning means comprises: a stereotactic manipulator providing two degrees of freedom of movement of said tool; and, a tool translation table supported on said stereotactic manipulator providing at least one further degree of freedom of movement of said tool and to enable said tool to be moved linearly into and out of said eye through said predetermined point.
Preferably said tool translation table is supported with at least one degree of freedom on said stereotactic manipulator so that the position of a tip of said tool can be adjusted to compensate for defects in the structure or form of the tip.
Preferably said tool translation table is further provided with at least one actuator under control of said remote control means to operate or otherwise work said tool.
Preferably one pair of lasers is supported on said tool translation table, said one pair of lasers arranged so that their respective laser beams mutually intersect each other at said predetermined point; and, a second pair of lasers is supported on said stereotactic manipulator in a plane different to that containing said one pair, said second pair of lasers arranged so that their respective laser beams mutually intersect each other at said predetermined point.
Preferably said remote control means comprises a computer operatively associated with said tool support and position means, said computer provided with a joystick and/or keyboard for receiving instructions from a surgeon to manipulate and control the position and operation of said tool.
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Constable Ian Jeffrey
Cringle Stephen John
Yu Dao-Yi
Larson & Taylor PLC
Philogene Pedro
The Lions Eye Institute of Western Australia Incorporated
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