MXPA99003159A - Tip formation for inserting a flexible membrane into an eye - Google Patents

Abstract

A tip formation (18) for an instrument for inserting a flexible membrane (37) into an eye is formed at the distal end (22) of a cannula (16). The cannula (16) has a lumen (18) which directs the flexible membrane (37) through an incision and into the eye. The distal end (22) is beveled so as to provide ease of entry into the incision, and to orient the discharge opening for the flexible membrane (37) at an inclination to the longitudinal axis of the lumen (18). The cannula walls (24) about the beveled end (22) are tapered to form a smaller sized end without impeding the advance of the membrane (37).

Description

TRAINING OF TIP TO INTRODUCE A FLEXIBLE MEMBRANE IN AN EYE FIELD OF THE INVENTION The present invention relates to a tip formation for an instrument for introducing a flexible intraocular lens or other flexible membrane into an eye.

BACKGROUND OF THE INVENTION The natural lens of the eye plays a primary role in focusing light on the retina for correct vision. However, vision through the natural lens may deteriorate due to injury, or due to the formation of a cataract caused by aging or disease. To restore vision, the natural lens is typically replaced by an artificial lens. An artificial lens can also be implanted as a replacement or supplement of the natural lens to make a refractive or other vision correction. The natural lens is removed in general by the use of a thin implement that is inserted through a small incision in the eye. The implement includes a cutting tool that is vibrated ultrasonically to emulsify the lens. The emulsified fragments of the lens are aspirated from the eye through a passage provided in the cutting tool. The fine nature of the implement allows for the removal of the lens through a small incision in the eye. The use of a small incision compared to other procedures that require a large incision can reduce the trauma and complications experienced during surgery and postoperatively. The artificial lens is composed of a flexible material so that the lens can be folded and / or compressed to a smaller size in cross section, and thus avoid enlargement of the incision during lens implantation. For this, the inserts typically include a lens reduction structure that serves to reduce the cross-sectional size of the lens, and a cannula with a lumen to direct the lens to the eye. The lens reduction structure has taken many different forms including, for example, articulated sections that close around a lens and tapered lumens that compress the lens as it is moved forward toward the eye. The cannula is a thin-walled thin tube at its distal end that guides the lens through the incision and into the eye. The lumen along the distal portion of the cannula generally has a substantially uniform configuration and size (ie, with only a slight taper for molding purposes) to avoid large additional forces needed to further compress the lens. By maintaining a substantially uniform lumen, the risk of breaking the thin walls is mitigated. Although there is great interest in making the distal end of the inserter as narrow as possible, there are practical considerations that have limited the extent to which the size of the cannula can be reduced. For example, as mentioned above, large inwardly directed forces are needed to further reduce a lens that is already tightly compressed. As a result, merely reducing the diameter of the lumen at its distal end to achieve a smaller cannula will at some point increase the forces directed inward to prevent the lens from advancing or rupture the walls. In addition, further thinning of the walls to reduce the cannula without narrowing the lumen will also result in at some point breaking the walls of the cannula during use.

COMPENDIUM OF THE INVENTION The present invention relates to a tip formation for an instrument used to insert a flexible intraocular lens or other flexible membrane in an eye. The present tip formation is formed at the distal end of a cannula that directs a lens to the eye. The distal end is beveled to facilitate entry into the incision and to orient the discharge hole for the lens at an in-clination to the longitudinal axis of the lumen. The cannula walls around the beveled end taper to form a smaller end without impeding the advancement of the lens. The tip formation reduces the circumference and the diameter of the distal end of the cannula without a concomitant reduction of the cross-sectional area of the path through which the lens is passed or a decrease in the thickness of the side walls of the cannula. As a result, the use of an inserter with the present tip formation allows to minimize the size of the incision and facilitate the introduction of the instrument into the improved eye. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of an inserter with a tip formation according to the present invention. Fig. 2 is an exploded cross-sectional view taken along line 2-2 in Fig. 1. Fig. 3 is a partial side view, in elevation, of the tip element of the inserter showing the tip formation present. Figure 4 is a partial top plan view of the tip element. Figure 5 is a partial bottom view of the tip ele- ment taken along line 5-5 in Figure 2. Figure 6 is a cross-sectional view taken along line 6-6 in the figure. 4. Figure 7 is a cross-sectional view taken along line 7-7 in Figure 3. Figure 8 is a side elevational view, broken away, of a second embodiment of an inserter with a tip formation as the present invention. Figure 9 is a side elevational view of the cartridge of the inserter of the second embodiment. Figure 10 is a perspective view of the cartridge. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a tip formation for an instrument used to insert a flexible intraocular lens or other flexible membrane into an eye. The tip formation is formed at the distal end of a cannula and could be used with virtually any lens insertion device that uses a tubular element to direct the lens to an eye. In a preferred embodiment, the tip formation 10 of the present invention is formed at the distal or free end 22 of a cannula 16 (Figures 2-7). The cannula includes a lumen 18 defining a generally linear path along a longitudinal axis 19 for directing a lens of reduced size through a small incision in an eye (Figures 2 and 3). The distal end of lumen 18 is open to form a discharge hole 23 for implanting the lens in an eye. The distal end 22 of the cannula 16 is bevelled to orient the discharge hole 23 at an inclination to the longitudinal axis 19. The term "chamfered" used in this application is intended to indicate a surface that is oriented at least in part to an inclination to the axis longitudinal of the lumen, regardless of the angle of inclination, whether the cut is linear or curved, whether the surface is regular or irregular. The beveled free end 22 defines a leading edge 26 and a trailing edge 27 of the discharge hole 23 (Figures 2, 3, 5 and 7). The wall portion 24 of the cannula 16 extending between the trailing edge 27 and the leading edge 26 converges in the forward direction. In the preferred construction, the taper of the wall portion 24 begins in an imaginary perpendicular plane that extends through the trailing edge 27 and continues to the leading edge 26. In addition, the wall portion 24 is preferably substantially shaped to the shape of a conical segment, such that the entire periphery converges towards the longitudinal axis 19. However, the convergence of the wall portion 24 could have a different shape, be discontinuous, or extend only along a length of part of the distance between the trailing edge 27 and the leading edge 26. The convergence of the wall portion 24 towards the shaft 19 serves to reduce the size of the distal end of the cannula to facilitate insertion of the insertion instrument into the incision. , and to minimize the size of the incision. In addition, the reduction of the distal end 22 is achieved without thinning the cannula walls or preventing the advance of the lens to the eye. The provision of a beveled free end through a tubular element creates a discharge hole that is larger than would be the discharge hole if it were formed so as to be perpendicular to the passage of the tubular element. According to the present invention, the additional space gained by providing a sloping discharge hole is advantageously used to reduce the size of the free end of the cannula. In other words, the wall portion 24 adjacent the inclined discharge hole 23 converges to narrow the outer surface of the cannula 16 forward of the trailing edge 27 without causing the discharge hole to have a smaller area than the cross-sectional area perpendicular to lumen 18 at the trailing edge 27. In the preferred construction, the distal walls of the cannula are formed as a thin tube to minimize the size of the tip to pass to the eye. The portion 18a of the lumen 18 that is rearwardly or upwardly of the trailing edge 27 has a substantially uniform internal configuration and size (i.e., with the slight conventional taper for molding purposes) to direct the lens to the eye without the application of high additional forces associated with the additional compression of a lens. The discharge hole 23 is inclined at an angle of 45 ° to the axis 19 to define the leading edge 26 and a trailing edge 27 (figures 2 and 3). The wall portion 24 converges forward at an included angle of about 20 ° (i.e., 10 ° relative to the axis 19) from an orthogonal plane aligned with the trailing edge 27. Despite the reduced exterior of the cannula, the The perpendicular cross-sectional area of the lumen 18 at the trailing edge 27 is substantially equal to the area of the discharge hole 23 so as not to impede the advance of the lens to the eye (Figures 5 and 6). In a preferred example, the area of the discharge hole 23 and the perpendicular cross section of the lumen at the trailing edge 27 are equal to about 2.58 mm2 (0.004 square inches). Many variations can be made in the preferred tip formation without departing from the spirit of the invention. For example, the converging wall portion 24 may converge at an exchange rate or begin to converge in forward or downward positions of the trailing edge 27. In addition, the bevelled surface may be fixed at different inclinations or be provided with non-linear The area of the discharge hole can also continue, of course, to be somewhat larger than the cross-sectional area perpendicular to the trailing edge 27, if the convergence starts forward of the trailing edge or a lower level of convergence is used. In the preferred embodiment, the tip formation 10 is an integral part of a discrete point-of-a-piece element 31 for an inserter 30 (Figures 1 and 2). The inserter 30 has a construction as described in U.S. Patent Application Serial No. 08 / 286,557, filed August 5, 1994, which is incorporated herein by reference. In general, the inserter 30 includes a tubular element 32, a cover 34, and a plunger 36 together with the tip element 31. The tubular element 32 has a cavity that opens rearward 34 to receive the plunger 36, and a shelf which protrudes forward 38 to receive a lens 37. The cover 34 covers the shelf to enclose the lens and define the station 40 to hold and retract the lens. In practice, the lens is placed on the shelf 38 and enclosed with the cover 34. The base portion 42 of the tip element 31 is pushed on the shelf and cover, and fixed in place with a detent 46 to form a integral unit with the tubular element 32. The plunger 36 is pushed forward to move the lens forward through the station 40, which folds the lens, and to the tapered segment 45 of the lumen 18. The combined effects of retraction and Compression of the station 40 and the tapered segment 45 define a lens reduction structure that reduces the lens size to a cross-sectional size small enough to fit through the narrow incision in the eye. The portion 18a of the lumen 18 has a substantially uniform configuration and size to guide the lens upward to the trailing edge 27 of the discharge hole 23 without considerable additional compression of the lens. The lens is then fed through the tip formation 10, it leaves the discharge hole 23, and enters the eye. However, despite the convergence of the wall portion 24, the area of the discharge hole is still the same as or greater than the perpendicular cross-sectional area of the lumen at the trailing edge 27. Alternately, the tip formation 10 it could be formed at the end of other inserters that use a cannula to direct the lens to an eye, regardless of the type of lens reduction structure that is used, whether the inserter is made up of a single piece or multiple pieces, or whether the training tip is a part of a cartridge or inserter tip. For example, tip formation 10 could be provided at the distal end of a cartridge 50 (Figures 8-10). The cartridge 50 has a tapered lumen 53 inside the cartridge as a lens reduction structure. After loading the lens into the lumen, the cartridge is placed in the insertion device 54 having a plunger 56 for moving the lens to an eye. Similarly, tip formation 10 may also be formed at the end of a cartridge as described in U.S. Patent No. 5,494,484 to Feingold, which is incorporated herein by reference. In this case, the cartridge includes articulated sections such as the lens reduction structure that close around the lens to reduce the cross-sectional size of the lens. The cartridge is then placed inside an insertion device that moves the lens forward to an eye. As another example, the tip formation 10 could be used with an inserter having a one-piece tubular element as described in United States Patent Application Serial No. 08 / 721,349, filed on September 26, 1996, by Cicenas et al., Which is incorporated herein by reference. In this device, the lens reduction structure includes a laterally mobile compressor to obtain an initial reduction in the cross-sectional size of the lens, and a tapered lumen that further reduces the size of the lens as it moves toward the eye. The tip formation 10 is formed in the distal end of the cannula in a manner identical to that described above. The above explanation refers to the preferred embodiments of the present invention. Various other embodiments as well as many changes and alterations can be made without departing from the spirit and broader aspects of the invention defined in the claims.

Claims (33)

1. CLAIMS 1. A tip formation for an instrument for introducing a flexible membrane into an eye, said tip forming including a cannula having a lumen for directing the flexible membrane to an eye, a free bevelled end that includes a leading edge and a trailing edge, and a hole in said beveled free end to discharge the flexible membrane of said lumen, said cannula having a first generally uniform portion immediately back of said trailing edge and a second portion between said leading and trailing edges converging towards said leading edge at a higher rate than said first portion.
2. 2. A tip formation according to claim 1, wherein said discharge hole has an area that is substantially equal to or greater than a perpendicular cross-sectional area of said lumen in said first portion at said rear edge of said discharge hole.
3. A tip formation according to claim 1, wherein said first portion of said cannula extends along a longitudinal axis of said cannula, and said bevelled free end is inclined at an angle of about 45 degrees with respect to to the longitudinal axis.
4. 4. A tip formation according to claim 1, wherein said first portion of said cannula includes opposite wall portions that are substantially parallel to each other.
5. A tip formation according to claim 1, wherein said second portion of said cannula converges the entire distance between said trailing edge and said leading edge.
6. 6. A tip formation according to claim 1, wherein said second portion of said cannula substantially conforms to a conical segment.
7. 7. A tip formation for an instrument for introducing a flexible membrane into an eye, said tip forming including a cannula having a lumen for directing a flexible membrane to an eye, a free bevelled end defining a discharge hole for said lumen, said discharge hole including a trailing edge and a leading edge, a first wall portion immediately back of said trailing edge, and a second wall portion between said leading edge and said trailing edge, said second edge inclining. wall portion relative to said first wall portion, and said discharge hole having an area that is greater or substantially equal to a perpendicular cross-sectional area of said lumen in said first wall portion at said rear edge of said hole. discharge.
8. A tip formation according to claim 7, wherein said second wall portion of said cannula converges the entire distance between said trailing edge and said leading edge.
9. 9. An instrument for introducing a flexible membrane into an eye, said instrument including: a reducing structure for reducing the cross-sectional size of the flexible membrane; and a tip formation including a cannula having a lumen for directing the flexible membrane to an eye, a free bevelled end that includes a leading edge and a trailing edge, and a hole in said free end for discharging the flexible membrane of said lumen, said cannula having a first generally uniform portion immediately rearward of said trailing edge, and a corresponding portion between said leading edge and said trailing edge converging toward said leading edge at a rate greater than said first portion.
10. 10. An instrument according to claim 9, wherein said discharge hole has an area that is substantially equal to or greater than said cross-sectional area perpendicular to said lumen in said first portion at said rear edge of said discharge hole.
11. An instrument according to claim 9, wherein said first portion of said cannula extends along a longitudinal axis, and said beveled free end is inclined at an angle of about 45 degrees relative to the longitudinal axis.
12. 12. An instrument according to claim 9, wherein said first portion of said cannula includes opposite wall portions that are substantially parallel to each other.
13. An instrument according to claim 9, wherein said second portion of said cannula converges along the entire distance between said trailing edge and said leading edge.
14. 14. An instrument according to claim 9, wherein said second portion of said cannula substantially conforms to a conical segment.
15. 15. An instrument according to claim 9, further in- cluding a plunger for moving the flexible membrane forward through said lumen and to the eye.
16. 16. An instrument according to claim 9, further including an insertion device and a cartridge removably re-seated in said insertion device, wherein said cartridge includes said reducing structure.
17. 17. An instrument according to claim 16, wherein said tip formation is formed as a part of said cartridge.
18. 18. A tip formation according to claim 1, wherein said first portion of said cannula includes opposite wall portions converging toward said trailing edge.
19. 19. A tip formation according to claim 7, wherein said first portion of said cannula includes opposite wall portions converging toward said trailing edge.
20. 20. An instrument according to claim 9, wherein said first portion of said cannula includes opposite wall portions converging toward said trailing edge.
21. 21. An instrument for introducing a flexible membrane into an eye that includes a tubular element that includes a passage for receiving a flexible membrane, said passage having an open distal end, and a plunger received movably along a longitudinal axis in said step for moving the flexible membrane forwardly through said open end and to an eye, said open end having a center that is offset from said longitudinal axis.
22. 22. An instrument according to claim 21, wherein said open end of said passage is inclined relative to said longitudinal axis.
23. 23. An instrument according to claim 21, wherein said tubular element includes a beveled free end at said open end of said passage, and said tubular element converges along the beveled free end.
24. 24. An instrument according to claim 23, wherein said tubular element converges along the beveled free end at a rate greater than a portion of the tubular element immediately back of the free bi-sealed end.
25. 25. An instrument for introducing a flexible membrane into an eye, including a tubular element that includes 2o a step for receiving a flexible membrane, said step having an open distal end and defining a non-linear path along which the flexible membrane is displaced to an eye, and a plunger movably received in said step to move the flexible membrane forward along said path and through said open end to insert it into the eye.
26. 26. An instrument according to claim 25, wherein said open end of said passage is inclined relative to said longitudinal axis.
27. 27. An instrument according to claim 25, wherein said tubular member includes a beveled free end at said open end of said passage, and said tubular element converges along the beveled free end.
28. 28. An instrument according to claim 27, wherein said tubular element converges along the bevelled free end at a rate greater than a portion of the tubular member immediately back of the beveled free end.
29. 29. An instrument according to claim 25, wherein the tubular member includes a proximal portion defining a linear path segment for the flexible element along a longitudinal axis and a distal portion that directs the flexible membrane as directed. length of a path that is not coaxial with said longitudinal axis.
30. 30. An instrument according to claim 29, wherein said open distal end discharges the flexible membrane of the tubular member along a path segment that is inclined with respect to the longitudinal axis.
31. 31. A process for introducing a flexible membrane into an eye that includes loading a flexible membrane into a tubular instrument having a passage, said passage including an open end for discharging said flexible membrane, moving the flexible membrane forward along a length of substantially linear travel through said passage and towards said open end, and discharge the flexible membrane of the passage in a direction that is not coaxial with the linear path.
32. 32. A process according to claim 31, wherein said flexible membrane is moved forward by an embolus received in the passage.
33. 33. A process according to claim 31, wherein said flexible membrane is compressed as it is moved forward,