Surgical Irrigation Sleeve Formed of Polyether Block Amide Resin

An ophthalmic surgical irrigation assembly for attachment to an ophthalmic surgical instrument. The assembly includes an elongated sleeve having a hollow interior space through which fluid is passed and surrounds a majority length of a cannula attached to the ophthalmic surgical instrument. A fluid port formed adjacent a distal end of the elongated sleeve allows the fluid to exit the interior space. A distal opening in the elongated sleeve allows a distal portion of the cannula to extend beyond the distal opening. A hub integrally formed with a proximal end of the elongated sleeve is adapted for fluid tight attachment to at least a portion of the surgical instrument and allows fluid to flow from the surgical instrument through the interior space and exit out of the fluid port. The elongated sleeve and the hub are each formed of a polyether block amide resin.

FIELD

The present disclosure relates to surgical irrigation sleeves, particularly to coaxial ophthalmic surgical irrigation sleeves for providing irrigating fluids into an eye during surgery.

BACKGROUND

The use of coaxial irrigation sleeves in ophthalmic surgery is well known. For example, silicone sleeves have been in use for decades and provide good wound sealing properties as well as thermal insulating properties. The thermal insulating properties protect the eye tissue from thermal damage, sometimes referred to as corneal burns, while a ultrasonic Phaco needle is vibrated during surgery.

While the known silicone sleeves can be effective, one major drawback is that the supple sleeves tend to collapse when a surgeon attempts to insert the sleeve and needle through the eye incision. To combat sleeve collapse the prior art has added ribbed structure along the sleeve or provided a rigid inner layer to stiffen the sleeve. Other sleeve collapse avoidance techniques have included a tight-fit between a thin sleeve distal end and the needle.

It is also known to form an irrigation sleeve out of hard, thermoplastic polyurethanes, polyesters, or polyolefins as disclosed in U.S. Pat. No. 4,897,079. However, the sleeve materials disclosed have a durometer of at least 60 Shore D, which is quite hard and is not likely to create an effective seal with the eye incision.

It would be desirable to provide an irrigation sleeve that is soft enough to sufficiently collapse to create a seal with eye incision but yet hard enough to not collapse upon insertion through the eye incision.

DETAILED DESCRIPTION

Current trends in ophthalmic surgery are demanding ever smaller diameter needles and smaller incisions. It is believed that smaller incisions lead to less change in corneal curvature and better visual acuity post-operation. These smaller incisions have led to tighter interfaces with the sleeves and needles. A problem, becoming more prevalent, is that the prior art silicone sleeve tends to accordion, i.e. collapse, at the incision, as the surgeon attempts to insert the sleeve and needle through the incision. This prior art problem is shown atFIG.1. A needle10has passed through an incision12in an eye14, but a sleeve16has accordioned at18outside the eye14. Needle10may be attached to a phaco handpiece20in a known manner, typically via a threaded connection, as shown. It is critical that sleeve16pass through incision12and into the eye14along with needle10, so that sleeve16can protect the eye tissue from damage and to provide irrigation fluid into the eye14.

FIG.2shows an ophthalmic surgical irrigation assembly21, in accordance with the present disclosure. Assembly21may include an elongated sleeve20having a hollow interior space (not shown) through which fluid36passes. Sleeve20coaxially surrounds a majority length of a cannula22having a distal end portion24and a proximal end26. Proximal end26is typically attached to a conventional phacoemulsification handpiece (not shown but essentially the same as inFIG.1) and the handpiece may include a port (not shown) for delivering irrigation fluid36between the sleeve20and cannula22. Sleeve20includes an elongated, resilient essentially tubular portion28having a distal end30and a proximal end32for surrounding a majority portion of a shaft of the cannula22. At lease one fluid port34(though typically at least two fluid ports) is formed adjacent the sleeve distal end30for allowing the fluid36to exit the interior space. A distal opening (indicated by38) is formed in the sleeve20and allows the distal end portion24of the cannula22to extend beyond the distal opening38. Sleeve proximal end32includes an enlarged hub40, as shown, integrally formed with the sleeve20at a proximal end of tubular portion28. The hub40is adapter for fluid tight attachment to at least a portion of the surgical instrument for allowing the fluid36to flow from the surgical instrument through the interior space and exit out of the fluid port34. The elongated sleeve20and the hub40are each formed of a polyether block amide resin to reduce the risk of the elongated sleeve collapsing at the eye incision.

The polyether block amide resin allows elongated sleeve20along tubular portion28to be compressible by an eye incision42, after insertion through the eye incision42for forming a fluid seal (shown at44) to reduce fluid leakage at the eye incision. The polyether block amide resin enables the elongated sleeve20to not be substantially collapsed by the eye incision44during normal surgical use, thus allowing a continuous flow of fluid36out of the fluid port34.

The sleeve distal end30may have a close-fit proximate cannula distal end24for retaining the sleeve distal end30near the needle distal end24.

Preferably, the irrigation assembly is molded as a single unit. Also, the ophthalmic surgical instrument may be a phacoemulsification instrument, as described above, or may be an irrigation/aspiration instrument (not shown).

Preferably, the polyether block amide resin has a durometer of about 95 Shore A or less and more preferably 90 Shore A or less. It has been discovered that such a durometer is soft enough to form an effective seal at the eye incision yet hard enough not to collapse the sleeve outside the eye incision while attempting insertion through the eye incision and for the sleeve not to be collapsed by the eye incision after insertion. The polyether block amide resin also preferably has a flexural modulus of at least about 10,000 pounds per square inch (psi) (about 703 kg/cm 2) and more preferably at least 12,200 psi (about 858 kg/cm 2). The polyether block amide (PEBA) resin may be marketed by Arkema Inc. as PEBAX® 4033 SA 01 Med or by Evonik Industries under the brand VESTAMID®E brand.

The PEBA resin described in this specification is believed to provide superior combined wound sealing and stiffness for insertion through the eye incision compared to the prior art polyurethanes, polyesters, or polyolefins as disclosed in U.S. Pat. No. 4,897,079. The materials disclosed in the '079 patent are significantly harder (60-90 Shore D) than those of the present invention (90-95 Shore A, roughly equivalent to 35-46 Shore D). In this way, the present invention provides a better seal at the eye incision while being stiff enough for insertion but yet more flexible than (not a hard as) the '079 sleeve.

A sleeve in accordance with the present invention by also be formed of other Nylon materials that result in the unique improvements for sleeves described above, including resistance to tearing, twisting, and buckling while retaining it's ability to conform to the incision to seal and prevent wound leakage. PEBA sleeves, as described above, also offer improved function for angled phaco needles addressing some of the bunching and buckling issues common to the angled needle application. These improvements are aided by use of a higher durometer than typically available in common prior art silicone sleeves but of a lower durometer than other prior art sleeve materials.

In addition to the preferred durometer range, the stiffness properties combine with the low surface friction in a manner that was not foreseen and offers sleeve performance that is a major advancement beyond the current silicone sleeves.

The PEBA resin disclosed above and other nylon materials have the advantage of being able to form sleeves that are easier to net mold and provide better overall performance in the eye compared with prior art surgical irrigation sleeves.