Patent Application
20160367319
Embodiments of the invention relate to laser probes used in ophthalmologic surgeries. More particularly, embodiments of the invention relate to laser probes which are capable of bending to send light into areas typically not accessible with straight laser probes.
Some prior-art laser probes include a pre-curved, nitinol (a nickel and titanium alloy) tube and a metal (e.g., stainless steel) straightening member, which is used to straighten the nitinol tube. In such devices, the straightening member is located on the outside of the nitinol tube in a telescoping manner. Because the straightening member is positioned outside of the nitinol tube, the straightening member is larger and is made from a larger amount of material in comparison to the nitinol tube. Generally speaking, the relatively large amount of stainless steel used in the straightening member provides sufficient stiffness to the member to straighten the nitinol tube.
In other laser probes, including laser probes designed by one or more of the current Applicants, the straightening member is positioned inside a pre-curved, non-metallic, tube. In such laser probes, the pre-curved tube is made from polymeric, flexible materials, such as polyether ether ketone (PEEK). As a result of using a non-metallic material for the outer pre-curved tube, the straightening member (regardless of the amount of material from which it is made) is usually sufficiently stiff to straighten the outer pre-curved tube.
Placing a straightening member inside a pre-curved nitinol tube, however, does have drawbacks. An inner straightening member is generally smaller, and made from less material than an outer straightening member. As a result, an inner straightening member generally does not provide sufficient stiffness to straighten the pre-curved nitinol tube. Nitinol is generally stiffer than the non-metallic materials used in certain laser probes. As a consequence of using a stiffer outer tube and a less stiff inner member, full straightening of a nitinol, outer, pre-curved member with an inner straightening member is difficult, if not, impossible to achieve in practical manner.
In one embodiment, the invention provides a steerable laser probe including an optical fiber, and a first tubular sleeve. The first tubular sleeve is positioned co-axially with the optical fiber relative to an axis. The first tubular sleeve includes a first curved portion. The steerable laser probe also includes a straightening sleeve positioned co-axially with the first tubular sleeve and the optical fiber relative to the axis. The straightening sleeve includes a second curved portion. The second curved portion facilitates a more complete straightening of the first tubular sleeve in comparison to prior designs.
In another embodiment, the invention provides a steerable laser probe including an optical fiber, and a first tubular sleeve. The first tubular sleeve is positioned co-axially with the optical fiber relative to an axis. The first tubular sleeve includes a nickel alloy. The steerable laser probe also includes a straightening sleeve positioned co-axially with the first tubular sleeve and the optical fiber relative to the axis. The straightening sleeve includes a steel alloy. A second thickness of the straightening sleeve is between about 1.5 and about 3 times a first thickness of the first tubular sleeve.
Other aspects of embodiments of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.
The optical fiber 14 is positioned within the flexible tubular sleeve 18 and the straightening sleeve 22. The optical fiber 14 includes a proximal end 34 and a distal end 38. The distal end 38 of the optical fiber 14 extends beyond the handle 26 and is connected to a laser source 42. The proximal end 34 of the optical fiber 14 is used to direct laser energy to a specific area. As discussed above, in some embodiments, the optical fiber 14 is used to illuminate parts of the human body, in particular parts of an eye, that are inaccessible to external light sources. The optical fiber 14 guides energy (in the form of light) from the laser source 42. Thus, the location and orientation or positioning of the optical fiber 14 determines the particular location to which laser energy from the laser source 42 is directed. Bending or curving of the optical fiber 14 changes the direction of the light and, ultimately, the location to which the light and/or laser energy is directed.
The flexible tubular sleeve 18 interacts with the optical fiber 14 to control the direction of the laser energy from the optical fiber 14. The flexible tubular sleeve 18 is secured to the handle 26 to inhibit movement of the flexible tubular sleeve 18 relative to the handle 26. The flexible tubular sleeve 18 is made from a nickel alloy material. In the illustrated embodiment, the flexible tubular sleeve is made from or composed of nitinol (e.g., a nickel and titanium alloy). The flexible tubular sleeve 18 includes a proximal end 50 and a distal end 54. The proximal end 50 of the flexible tubular sleeve 18 is approximately coterminous with the optical fiber 14. The distal end 54 of the flexible tubular sleeve 18 is fixed, at least temporarily, to the handle 26.
As shown in
As also shown in
Referring back to
The curved portion 58 of the flexible tubular sleeve 18 is anneal set at a temperature of approximately 540° C. Setting the flexible tubular sleeve 18 at such a relatively high temperature, restores the super-elastic properties to nitinol. In other words, the flexible tubular sleeve 18 is elastic such that the shape of the flexible tubular sleeve 18 may be temporarily changed. In practice, the elastic modulus for hypodermic nitinol tubing varies from 10.9 Mpsi (i.e., 10.9×106 psi) to approximately 5.8 Mpsi (i.e., 5.8×106 psi) based on, for example, different methods and temperatures used in the setting process.
The straightening sleeve 22 is positioned between the optical fiber 14 and the flexible tubular sleeve 18. The straightening sleeve 22 is coupled to the handle 26. The handle 26 includes an actuator 64 that allows a user to control the depth of insertion of the steerable laser probe 10 and the movement of the straightening sleeve 22. In particular, the actuator 64 is connected to the straightening sleeve 22 and is configured to move the straightening sleeve 22 relative to the flexible tubular sleeve 18 and the optical fiber 14. The straightening sleeve 22 is movable, via the actuator 64, between a first portion (P1), as shown in
Preferably, the straightening sleeve 22 is made from a steel alloy. In one particular embodiment, the straightening sleeve 22 is made from stainless steel. In the illustrated embodiments, the straightening sleeve 22 is made from type 303, work-hardened stainless steel. This type of stainless steel has spring-like elastic properties and a minimum yield strength (Sy) of 140 ksi. The elastic modulus of the stainless steel used in certain embodiments is approximately 30 Mpsi (i.e., 30×106 psi). In the illustrated embodiment, the straightening sleeve 22 has an inner diameter of 0.0085 inches, an outer diameter of 0.0186 inches, and an associated thickness of approximately 0.00505 inches. As shown in
As discussed above, the straightening sleeve 22 should have sufficient stiffness to straighten the flexible tubular sleeve 18. In the illustrated embodiment, for example, a spring constant of the flexible tubular sleeve 18 can be compared to a spring constant of the straightening sleeve to analyze more quantitatively how much stiffness the straightening sleeve 22 has or provides. A spring constant of the flexible tubular sleeve 18 can be calculated by multiplying the elastic modulus and a moment of inertia associated with the flexible tubular sleeve 18. The elastic modulus associated with the flexible tubular sleeve 18, as discussed above, varies between 5.8 Mpsi and 10.9 Mpsi. The moment of inertia of the flexible tubular sleeve 18 is determined based on the inner and outer diameters of the flexible tubular sleeve 18. In particular, for the illustrated embodiment, the moment of inertia for the flexible tubular sleeve 18 is approximately 3.68×10−9 in.4, which yields a spring constant ranging from 0.0213 to 0.0401 lb./in. for the flexible tubular sleeve 18.
The spring constant can be analogously calculated for the straightening sleeve 22. The moment of inertia for the straightening sleeve 22 of the illustrated embodiment is approximately 5.61×10−9 in.4. As discussed above the elastic modulus for the straightening sleeve 22 is approximately 30 Mpsi. Accordingly, the spring constant for the straightening sleeve 22 is approximately 0.1104 lb./in. In other words, the spring constant for the straightening sleeve 22 is between 2.75 and 5.2 times the spring constant for the flexible tubular sleeve 18. Additionally, note that the elastic modulus for the straightening sleeve 22 is approximately between 275%-500% greater than the elastic modulus for the flexible tubular sleeve 18. Therefore, based on the illustrated dimensions of the straightening sleeve 22 and the flexible tubular sleeve 18, the straightening sleeve 22 can substantially straighten the flexible tubular sleeve 18 because the straightening sleeve 22 is stiffer than the flexible tubular sleeve 18.
In the embodiment shown in
In some applications, the slight bend B of the flexible tubular sleeve 18 may be insignificant or otherwise have little, if any, detriment to the use of the steerable laser probe in the desired manner. In other applications, however, the slight bend B may inhibit proper use of the steerable laser probe 10. Therefore, in some embodiments, the straightening sleeve 22 incorporates a corrective feature 68. The corrective feature 68 may be created by pre-stressing the straightening sleeve 22 to create a curved portion 72. The curved portion 72 bends in a direction that is opposite the bending direction of the curved portion 58 of the flexible tubular sleeve 18. For example, while the curved portion 58 of the flexible tubular sleeve 18 bends to the right, the curved portion 72 of the straightening sleeve 22 bends to the left. Maintaining opposite bending between the flexible tubular sleeve 18 and the straightening sleeve 22 increases the spring constant of the straightening sleeve 22.
As shown in
The decrease in diameter of the flexible tubular sleeve 18 (from 0.0235 inches to 0.0215 inches) allows the curved portion 58 to be more flexible than the straight portion 59. The thickness of the straightening sleeve 22, on the other hand, is uniform throughout its length. The change in outer diameter of the flexible tubular sleeve 18 allows the straightening sleeve 22 to straighten the curved portion 58 of the flexible tubular sleeve 18, but inhibits the curved portion 72 of the straightening sleeve 22 from bending the straight portion 59 of the flexible tubular sleeve 18. In other words, while the thickness of the straightening sleeve 22 is approximately 2.4 times larger than the thickness of the flexible tubular sleeve 18 at the straight potion 59, the thickness of the straightening sleeve 22 is approximately 4.59 times larger than the thickness of the flexible tubular sleeve 18 at the curved portion 58. The increase in thickness ratio (straightening sleeve 22 to flexible tubular sleeve 18) is related to the stiffness and straightening force provided by the straightening sleeve 22 to the flexible tubular sleeve 18, such that the straightening sleeve 22 can change the shape (e.g., straighten) the curved portion 58 of the flexible tubular sleeve 18, but not the straight portion 59 of the flexible tubular sleeve 18.
In some embodiments, the slight bend B of the flexible tubular sleeve 18 may be desired by a user. In such instances, the curved portion 72 of the straightening sleeve 22 includes a bend that is more heavily accentuated such that when the straightening sleeve 22 is in the first position, the flexible tubular sleeve 18 is bent in the direction of the bend B, not in the direction of the curved portion 58, as shown in
In other embodiments, the flexible tubular sleeve 18 is weakened by laser cutting lines or ridges along the length of the curved portion 58 of the flexible tubular sleeve 18. The curved portion 58 may be weakened in addition to or instead of decreasing the outer diameter of the curved portion 58 of the flexible tubular sleeve 18. When the curved portion 58 is weakened by creating ridges (e.g., partially cutting longitudinal lines along the curved portion 58), the straightening sleeve 22 can provide sufficient stiffness to straighten the curved portion 58 of the flexible tubular sleeve when the straightening sleeve 22 is in the first position.
A user inserts the steerable laser probe 10 into an area, such as a cavity in the eye, while the straightening sleeve 22 is in the first position. The user changes the angle of the projected laser energy from the optical fiber 14 by retracting the straightening sleeve 22 to the second position. When the steerable laser probe 10 needs to be removed from the area, the straightening sleeve 22 is moved back to the first position to inhibit the optical fiber 14 from curving. The steerable laser probe 10 is more easily removed from the area when in a straightened state.
In prior-art devices, steerable laser probes often position a flexible tube inside a rigid tube. The flexible tube moves from a retracted position to an extended position. In the retracted position, the flexible tube is co-axially positioned inside the rigid tube and inhibited from curving. However, in the extended position, the flexible tube moves past the rigid tube and is able to bend. However, as the flexible tube bends or curves, the flexible tube also experiences longitudinal displacement. A user has to account for the longitudinal displacement to direct the light from an optical fiber in a desired direction and such steerable probes require the user to adjust the depth of insertion of the probe.
Since the steerable laser probe 10 includes the straightening sleeve 22 in between the optical fiber 14 and the flexible tubular sleeve 18, and the straightening sleeve 22 retracts relative to the optical fiber 14 and the flexible tubular sleeve 18, the flexible tubular sleeve 18 bends or curves without experiencing longitudinal displacement. As a consequence, the steerable laser probe 10 provides a user with an easy way to direct laser energy from the optical fiber 14 to a desired location without requiring adjustment of the depth of insertion of the steerable laser probe 10 due to longitudinal displacement.
Thus, embodiments provide, among other things, a steerable laser probe that inhibits longitudinal displacement of the optical fiber while changing the angle at which light is directed. Various features and advantages of the invention are set forth in the following claims.
