Surgery – Means for introducing or removing material from body for... – With means for cutting – scarifying – or vibrating tissue
Reexamination Certificate
1999-06-09
2003-07-15
Casler, Brian L. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
With means for cutting, scarifying, or vibrating tissue
C604S035000, C604S521000, C604S500000, C606S171000, C606S169000
Reexamination Certificate
active
06592541
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates an improved ophthalmological instrument and phaco tip device used in the removal of a cataract nucleus from an eye and an improved cataract removal method.
2. Background Discussion
The current technology for cataract removal involves the use of ultrasound to dissolve, that is, emulsify, the nucleus, the hardest part of a cataract. This approach allows the cataract nucleus to be removed by washing it out through a tiny incision as small as 3 millimeters (mm) or less. Having a small incision allows safer surgery and rapid recovery. The one drawback to this technique is that exposure to ultrasonic energy needs to be kept to a minimum. Excess exposure causes damage to the very sensitive cornea. The chance of this happening is more likely when a cataract is dense or very hard. Long ultrasonic time exposures when trying to emulsify dense cataract nuclei may result in corneal damage and other complications.
It has been found that if the nucleus can first be segmented into smaller pieces, such as quarters, the ultrasonic exposure time can be greatly reduced even for very dense cataracts. The simplest approach to quartering the nucleus has been to use the regular ultrasonic emulsifier to cut a deep groove in the middle of the nucleus in an anterior posterior direction. The nucleus is then rotated 90 degrees and another groove cut deeply at right angles to the first groove, thus creating a “cross” pattern. Typically these grooves are about 1 to 1.5 millimeters in width and 3 millimeters deep, and intersect at about the center of the nucleus. Using a cracking device such as Katena nucleus splitters, the nucleus is then split into four quarters and each quarter removed by ultrasonic emulsification. A conventional phaco tip using ultrasonic energy for cutting these grooves comprises a hollow needle, having a passageway with a 1 mm to 1.5 mm diameter. Thus, the groove being cut is also equal to the tip diameter and is about 1 mm to 1.5 mm wide. The central opening in the ultrasonic tip is used to aspirate the emulsified and liquefied nucleus out of the eye as the emulsification proceeds.
Because the phaco tips used so far are 1 mm to 1.5 mm wide, the ultrasonic energy expended to cut through very hard nucleus is excessive, thus occasionally causing severe damage to the cornea. Also the nucleus may be too hard and simply not be able to be cut with such a conventional phaco tip. Thus, there may at times be a risk of dislocating the entire nucleus into the posterior region of the eye. Often under such conditions the ultrasonic procedure has to be abandoned and the surgeon has to resort to the old fashioned technique of opening the eye extensively with a knife to extract the cataract in its entirety, leading to a complicated prolonged surgical outcome.
In order to circumvent these above difficulties, Dr. Nagahara some years ago developed the concept of “natural cleavage planes” existing in the nucleus that could be used to advantage to essentially split (or chop, as he called it) the nucleus into two pieces by simply pushing a hook through the nucleus center. Although this technique has been popularized in the last few years, many surgeons still find it very difficult to use reliably.
More recently, a pre-chopper was introduced by Dr. Akoshi. The idea behind this pre-chopper was to make a very sharp pointed set of paddles in the form of a cross action forceps that could be pushed into the center of the nucleus and then pressed apart against each other, thus splitting the nucleus into 2 pieces. The difficulty has been that this pre-chopper only works well when the nucleus has a density neither too hard nor too soft. If the nucleus happens to be very soft, the paddles simply cause the nucleus material to get “mushed” without a splitting action. If the nucleus is anywhere too hard, the pre-chopper cannot be pushed into its center, deeply enough to split the nucleus. There is a serious risk of dislocation of the nucleus if further pressure is exerted. Very hard nucleus that will require excessive ultrasonic time exposure cannot be split with a pre-chopper.
All current phaco manufacturers have focused on making phaco machines more and more sophisticated with more available ultrasonic power, more vacuum, more pedals, and other features. Considering the steps involved in one of the more popular approaches to nucleus removal, the groove and crack approach, there are clearly at least two distinct steps involved that require the use of ultrasonic energy. The first step is to break the nucleus into smaller segments (usually quarters) and then to debulk, or remove each piece by emulsification. Breaking the nucleus into segments is achieved by deeply grooving the nucleus and then cracking the nucleus manually either with the standard phaco handpiece and another instrument (2 handed approach) or with a nucleus cracker (Katena, Rhein, etc.) in a one handed approach. The debulking step is performed with the same phaco tip used for making the initial grooves. It is a very inefficient in breaking the nucleus and debulking.
There are several disadvantages in using a standard single tip approach. Using one standard tip for both grooving the nucleus and debulking the segments is a very inefficient approach. In soft nuclei this approach manages to work, but when faced with a very hard nucleus, even a 45 degree beveled tip or a Kelman tip can take several minutes of phaco time to cut a groove deep enough. This also puts severe stress on the zonules. A phaco tip designed primarily for debulking, as all current tips are, works poorly as a cutting tool. To attempt to enhance the cutting action, manufacturers have advocated putting a 30 or 45 degree bevel to the tip. This improves the cutting characteristics of the tip, but exposes the cornea endothelial to excessive ultrasonic energy being released from the bevel face up position that is currently advocated. All currently available tips are 1-1.5 mm in diameter to allow for adequate aspiration of the released debris. When such a tip is used initially to just cut a groove, only the apex of the beveled tip is in contact with and is actually cutting nucleus. The greater portion of the face of the vibrating tip is in aqueous with the bevel facing upwards, thus transmitting most of the ultrasonic energy directly towards the cornea endothelium. Since the conventional phaco tip has ongoing aspiration, the tip has to be used with the bevel face up, thus directing a large part of the ultrasonic energy directly towards the corneal endothelium rather than into the cataract nucleus that needs to be cut.
SUMMARY OF THE INVENTION
This invention has several features, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this invention as expressed by the claims that follow, its more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled, “DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS,” one will understand how the features of this invention provide its benefits, which include, but are not limited to, safer surgical techniques, greater control by the surgeon during cataract removal, and reduction in damage to tissue during surgery.
This invention includes an ophthalmological device for cutting into a nucleus of a cataract. It employs a unique phaco tip. The first feature of this ophthalmological device is that the phaco tip has a body with a solid blade at its distal end. The solid blade has a face edge adapted to be placed in contact with the nucleus. This face edge is characterized in that it does not have any aspiration port therein. The face edge preferably has a surface area from about 0.4 to about 0.8 square millimeters, and a thickness from about 0.01 to about 0.6 millimeters. The width and height dimensions of the face edge at their greatest dimensions do not exceed the width and height dimensions of the body of the phaco tip.
The second feature is that the blade has
Casler Brian L.
Connors John J.
Connors & Associates, Inc.
Rodriguez Cris
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