Surgery – Specula – Retractor
Reexamination Certificate
2001-10-02
2003-09-16
O'Connor, Cary E. (Department: 3732)
Surgery
Specula
Retractor
C600S208000
Reexamination Certificate
active
06620098
ABSTRACT:
The present invention relates to a device for dilating a pupil and/or maintaining a pupil in a dilated state.
The invention has been developed primarily for use in ophthalmic surgery and will be described hereinafter with reference to this application.
BACKGROUND OF THE INVENTION
It is advantageous in many ophthalmic procedures for the pupil to be dilated as much as possible, that is for the iris to be retracted toward the outer edges of the eye. This normally occurs automatically when the eye is deprived of bright light, for example, in dark rooms or at night.
When performing ophthalmic operations, such as inserting an intra-ocular contact lens (ICL), in the posterior chamber, a dilated iris and pupil gives the surgeon a larger area to manipulate the ICL into position. The lens in the eye and its enclosing capsule are delicate structures that may be easily damaged by excessive contact pressure and shock. By maximising the area available to the surgeon there is a reduction in the risk of damaging the iris or human lens or other components of the eye due to unintentional contact with the various surgical instruments.
Retinal surgery involves operating on the retina on the back of the eye while occasionally viewing the retina inside the eye through the pupil. Again a large pupil is a definite advantage for the surgeon during this difficult procedure. Accordingly, maximising the dilation of the iris is of great assistance.
Cataract surgery involves replacing the natural human protein lens inside the eye with an artificial lens. This is usually done because the natural lens has degraded over time from the effects of ultra-violet rays and ageing such that the lens is no longer clear.
In some countries, the present procedure for removing the natural lens involves cutting a semicircle around the edge of the cornea of the eye folding back the resultant flap and physically removing the lens from its enclosing capsule through the iris. The lens is then replaced with a new relatively rigid artificial lens, the cornea returned to its original position and sutured into place. Recovery from this procedure is quite slow and the sutures may subsequently need to be removed.
In most Western countries and Japan, a more advanced procedure is performed involving an ultrasonic fractionator instrument known as a phaco-emulsifier. In this technique the pupil is usually dilated using a topical drug in the form of eye drops and an incision about 3 mm wide is made in the periphery of the cornea. The anterior chamber is inflated with a “visco-elastic” material to keep the anterior chamber fully formed and deep. A tool is introduced through this incision to tear away the anterior capsule covering the lens. The phaco-emulsifier is then introduced through the incision and used to break up the lens. The pieces being sucked out by the phaco-emulsifier and any remnants are drawn out by irrigation/aspiration. The new lens made of foldable material is then introduced through the wound and unfolded into place. The visco-elastic is then sucked from the eye and the procedure is complete. Stitching is not necessary and the patient need only stay overnight or may even be able to return home immediately. This technique is much less traumatic to the eye and much less costly in hospital stay and recuperative therapy.
About one in five patients do not achieve sufficient pupil dilation with topical drugs. Also such eye drops can wear off during an operation resulting in the iris contracting and reducing the pupil size during surgery. This complicates the removal of any lens remnants during and after phaco-emulsification as it is not possible to see inside the entire lens capsule when a portion of it is covered by the iris. Without sufficient pupil dilation, removal of the lens remnants is done by “feel” relying heavily on the experience of the surgeon. Experience has shown that thorough capsular “clean up” of the remnants significantly reduces the need for secondary clean up procedures following cataract surgery.
Insufficiently dilated pupils are also prone to damage from the tip of the phaco-emulsifier. With a small pupil there is a greater likelihood that the phaco-emulsifier tip will touch the inner edge of the iris during emulsification of the lens and cause permanent damage to the iris structures. This is most likely to occur at the inner edge of the iris diametrically opposed to the incision.
A number of physical and therefore surgically more complicated measures can be used to dilate the pupil and maintain it in a dilated state.
One method involves making four minor incisions at roughly 90° intervals around the periphery of the cornea and inserting a small hook-like apparatus through each incision. The hooks engage with the inner circumferential edge of the iris and when retracted, pull the iris outwards to define an enlarged substantially square shaped opening. Another physical method, known as sphincterotomy, involves making an incision into the cornea through which a blade is passed that makes radial cuts into the iris itself, thus allowing the iris to dilate and expose more of the lens. Both the above methods add extra time to the total operation time and the latter involves considerable risk of damage to the patient's iris. Moreover, the damage done in segmenting the iris during a sphincterotomy is irreversible and results in a permanently disfigured iris.
More recent advancements have included the use of generally annular dilating devices. These are usually made from resilient polymeric materials which are contractible to enable insertion through a small incision in the cornea, sclera or limbus and positioning within the iris, the resilient nature of the material acting upon placement to urge and maintain the iris outwardly into a dilated state. These types of prior art dilating devices can be divided into three separate categories.
The first category comprises dilating devices which in their expanded states generally form a complete annulus having surfaces thereon adapted to engage the inner edge of the iris. Examples of such devices are shown in U.S. Pat. No. 4,782,820 (Woods), U.S. Pat. No. 5,267,553 and 5,322,054 (Graether) and U.S. Pat. No. 4,387,706 (Glass).
The Glass device comprises a complete annular ring having a generally ‘L’ shaped cross section defining an inner axial wall and a posterior flange for seating behind the iris. The dilator is deformable via a pair of opposed pinions provided on the posterior flange. These pinions enable the dilator to be compressed to an oval configuration by the use of forceps to facilitate positioning of the device within the pupil. However, given the relatively rigid nature of the flanged structure and the absence of any means to retain the dilator in a direction parallel to the central axis of the iris, it is understood that practical use of this device in terms of both insertion into the anterior chamber of the eye and subsequent location within the iris would be extremely difficult if not impossible. This view is probably supported by the fact that it appears this design did not materialise into a commercially successful form.
The Graether patents then go on to describe a pupil expander that is generally ‘U’ shaped in-cross section forming an incomplete annulus, the ends of which are joined by a flexible connecting strap to make a complete circle. In use the expander is deformed into an elongated shape for insertion into the eye via a scieral incision. Elongation is preferably achieved by use of a specially designed jig which aligns the elongated ‘U’ shaped side walls for sliding onto special forcep tips. While it appears the ‘U’ shaped channel structure goes some way to addressing the iris retainment problem of Glass, its use is still a slow and awkward procedure and necessitates during insertion severe deformation of the iris into a “cat” like elongate slit which is potentially damaging to the iris.
Woods teaches what may well have been a further improvement over Glass, describing a device also having an elongated arcuate, flexible, resilient body that
Gottlieb Rackman & Reisman P.C.
Milvella PTY LTD
O'Connor Cary E.
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