Surgery – Instruments – Light application
Reexamination Certificate
1999-06-10
2001-12-11
Dvorak, Linda C. M. (Department: 3739)
Surgery
Instruments
Light application
C606S010000, C606S013000, C606S004000, C606S006000, C606S009000, C606S003000, C607S089000, C433S215000
Reexamination Certificate
active
06328732
ABSTRACT:
The invention relates to a device for treating bodily substances, comprising a laser beam source which produces pulsed laser radiation at wavelengths particularly in the infrared range, an arrangement for guiding the laser radiation to the location of treatment, and further comprising a control device by means of which the pulse energy and/or pulse length and/or pulse frequency can be adjusted.
Quite generally, the invention is suitable for treating bodily substances, i.e. producing an effect on bodily substances in many different ways. The term “treatment” may either refer to changing the conditions of these substances, or to removing these substances from the body, or to changing the position of the substances in the body. The bodily substances can be manifold, for example diseased tissue, or a substance generated in diseased form, or tissue which is sound per se but is to be removed for medical reasons. The following is a description of the invention with regard to what is known as intraocular cataract surgery.
A cataract is a change of the lens of the human eye, resulting in loss of transparency of the visible optical range of the lens. The region of the lens becomes cloudy. Loss of transparency causes impairment of vision.
Cataract surgery refers to the surgical treatment of the cataract, wherein the cloudy lens is removed from the path of light beams required for the optical perception. During the past centuries, such removal was done by what is known as cataract cracking, and the patient was then given so-called cataract lenses.
In 1949, the British ophtalmologist H. Ridley was the first to implant an artificial lens (PMMA) into the patient's eye after a cataract operation.
Accordingly, before implanting an interocular (new) lens, cataract surgery requires the original cloudy lens to be removed.
One criterion in cataract surgery recognised as being of growing importance is the fact that as much neighboring tissue structures as possible are to be maintained while the cloudy lens is being removed.
The surgical technique differentiates between the so-called intracapsular lens dispensation and the extracapsular cataract extraction. In the last-mentioned method it is the aim of the operation to remove the cloudy lens from the capsule of the lens, with the intention to leave said capsule of the lens in its anatomic position as much as possible.
Lately, the so-called phacoemulsification has been developed as an example for extracapsular cataract surgery (W. Böke “Phakoemulsifikation. Warum?”, Klin. Mbl. Augenheilk., 197 (1990) 100-105, F. Enke publishing house of Stuttgart). Basically, phacoemulsification is a standard surgical operation performed by means of a cut.
To reduce irritations of the tissue caused by cuts and other manipulations of the tissue, the so-called ultrasonic phacoemulsification has lately been used to a larger extent (see Jeffrey W. Berger, Jonathan H. Talamo, Keven J. LaMarche, Seon-Ho Kim, Robert W. Snyder, Donald J. D'Amico, George Marcellino “Temperature Measuring During Phacoemulsification and Erbium: YAG Laser Phacoablation in Model Systems”, Journal of Cataract Refract Surg., Vol. 22, April 1996, pp. 372 to 378). Due to such ultrasonic phacoe-mulsification, both the interoperative stresses as well as the postoperative complications may largely be reduced to a minimum. By means of this technique, the material of the lens is removed via an aspiration/irrigation system. The energy used to crack the lens is caused by ultrasonic vibrations which are applied to the body of the lens.
The energy required to crack the cloudy lens can also be provided by means of laser radiation (also see the above-mentioned article of J. W. Berger et al). In case of the so-called laser phacovaporization, for example by means of Er- YAG- or Er-YSGG lasers, the material of the lens is broken, due to the high absorption of the laser radiation in the IR region in the tissue to be treated, such cracking resulting in tissue ablation or tissue separation (Ray P. Gailitis, Scott W. Patterson, Mark A. Samuels, Kerry Hagen, Qiushi Ren, George O. Waring “Comparision of Laser Phacovaporization Using the Er-YAG and the Er-YSGG Laser”, Arch Ophtamol, Vol. 111, May 1993, pp. 697-700).
The present invention relates to the removal of a cloudy lens by use of laser.
Said above-mentioned problems do not only occur in cataract surgery but generally in treating substances of the human body (“bodily substances”) with laser radiation. When treating bodily substances with laser radiation it is generally important to treat only the diseased or changed regions by means of such radiation, whilst more or less adjacent regions should at best not be exposed to such radiation.
U.S. Pat. No. 4,572,189 describes an electronic control device for a surgical laser system in which only the maximum pulse number and two pulse durations can be predetermined. U.S. Pat. No. 4,933,843 and EP-A-0164751 describe surgical laser systems in which unsatisfactory adjustments of the system can be recognised by means of a menu control.
When used in cataract surgery, the invention relates to the technical problems arising from the different material of the lenses of different patients and from the non-homogeneity of the optical properties within a lens, and it is the object of the invention to provide a device for the intraocular cataract surgery as mentioned in the beginning so that the surgeon can be given a device which enables him to control the intraocular application of the laser energy to such an extent that it may be possible for him to remove the cloudy lens carefully without impairing the adjacent structures of the tissue.
According to the invention, this object relating to a device for the intraocular cataract surgery as mentioned above is solved in that the control device comprises a first arrangement by means of which an acceptable range for the pulse energy and/or pulse length and/or pulse frequency can be predetermined extent that the sound tissue remains unafflicted to the utmost amount.
When used in cataract surgery, the invention relates to the technical problems arising from the different material of the lenses of different patients and from the non-homogeneity of the optical properties within a lens, and it is the object of the invention to provide a device for the intraocular cataract surgery as mentioned in the beginning so that the surgeon can be given a device which enables him to control the intraocular application of the laser energy to such an extent that it may be possible for him to remove the cloudy lens carefully without impairing the adjacent structures of the tissue.
According to the invention, this object relating to a device for the intraocular cataract surgery as mentioned above is solved in that the control device comprises a first arrangement by means of which an acceptable range for the pulse energy and/or pulse length and/or pulse frequency can be predetermined before an operation, and a second arrangement by means of which the pulse energy and/or pulse length and/or pulse frequency can be adjusted to a given value or values within the predetermined range during the operation.
The invention is in particular also suitable for devices used in dermatology, particularly for the treatment of scars or wrinkles. When used in dermatology, fibrous material or an articulated arm with mirror as known per se can also be used as guide means, i.e. the radiation is guided to the required location via mirrors.
Furthermore, the invention is also suitable for devices used in dentology, in particular for the treatment of hard tooth substances such as dental enamel or dentin.
When used in dentology, an Er:YAG solid-state laser is particularly suitable as laser radiation source, and this preferably even in combination with another laser such as a Nd:YAG solid-state laser (wavelength: 1064 nm). It is preferred to use said two lasers in alternating manner via two different guide means, however, with the same control device according to the invention being provided for pulse energy, pulse length
Donitzky Christof
Pribbernow Arnold
Browning Clifford W.
Dvorak Linda C. M.
Farah Ahmed
Wavelight Laser Technologies GmbH
Woodard Emhardt Naughton Moriarty & McNett
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