Intraocular lens delivery device with a multi-part plunger tip

1. A method of delivering an IOL to an eye, the method comprising:

providing a delivery cartridge having an internal surface defining a lumen extending along the cartridge wherein at least a portion of the lumen has a cross-sectional area that becomes progressively smaller as the cross-sectional area is taken at locations progressively closer to a nozzle of the cartridge;

providing an IOL disposed within the cartridge; and

providing a plunger having a plunger tip that travels along the lumen of the cartridge, the plunger tip being defined by an internal member, an external member and an intermediate member, the external member being formed of a first material having an elongation at break that is at least 350% and the intermediate member being formed of a second material having an elongation at break that is no greater than 300%;

causing the plunger tip to travel along the at least a portion of the lumen such that the external member compresses a substantial amount while causing the IOL to fold and compress and while the intermediate member remains substantially non-compressed wherein the substantial amount of compression includes a movement of an outer surface of the external member to a distance at least 10% closer to the intermediate member; and

upon achieving the substantial amount of compression, causing the internal member to release from the intermediate member and continue the delivery of the IOL.

2. A method as in claim 1 wherein the substantial amount of compression includes a movement of the outer surface of the external member to a distance at least 30% closer to the intermediate member.

3. A method as in claim 1 wherein the external member is formed of a material having an elongation at break that is at least 800%.

4. A method as in claim 1 wherein the intermediate member is formed of a material having an elongation at break that is no greater than 50%.

5. A method as in claim 1 wherein the intermediate member is formed of a material having an elongation at break that is no greater than 100%.

6. A method as in claim 1 wherein the external member is formed of a first material, the intermediate member is formed of second material and the first material has an elongation at break that is at least two times an elongation at break of the second material.

7. A method as in claim 1 wherein the external member is formed of a first material, the intermediate member is formed of second material and the first material has an elongation at break that is at least four times an elongation at break of the second material.

8. A method as in claim 1 wherein the internal member is an end portion of a shaft of the plunger.

9. A method as in claim 1 wherein the material that forms the external member includes a substantial portion of elastomer.

10. A method as in claim 9 wherein the external member includes at least 30% by weight elastomer.

11. A method as in claim 9 wherein the external member includes at least 50% by weight elastomer.

12. A method of delivering an IOL to an eye, the method comprising:

providing a delivery cartridge having an internal surface defining a lumen extending along the cartridge wherein at least a portion of the lumen has a cross-sectional area that becomes progressively smaller as the cross-sectional area is taken at locations progressively closer to a nozzle of the cartridge;

providing an IOL disposed within the cartridge; and

providing a plunger having a plunger tip that travels along the lumen of the cartridge, the plunger tip being defined by an internal member, an external member and an intermediate member, the external member being formed of a first material having an elongation at break that is at least 350% and the intermediate member being formed of a second material having an elongation at break that is no greater than 100%;

causing the plunger tip to travel along the at least a portion of the lumen such that the external member compresses a substantial amount while causing the IOL to fold and compress and while the intermediate member remains substantially non-compressed wherein the substantial amount of compression includes a movement of an outer surface of the external member to a distance at least 20% closer to the intermediate member; and

upon achieving the substantial amount of compression, causing the internal member to release from the intermediate member and continue the delivery of the IOL wherein the internal member, the external member, the intermediate member or a combination thereof includes one or more retention features for releasably maintaining the intermediate member the external member or both in the same position relative to the internal member until the internal member releases from the intermediate member.

13. A method as in claim 12 wherein the external member is formed of a material having an elongation at break that is at least 800%.

14. A method as in claim 12 wherein the intermediate member is formed of a material having an elongation at break that is no greater than 50%.

15. A method as in claim 12 wherein the external member is formed of a first material, the intermediate member is formed of second material and the first material has an elongation at break that is at least four times an elongation at break of the second material.

16. A method as in claim 12 wherein the external member includes at least 30% by weight elastomer.