Patent Application
20080255577
This invention relates to intraocular lenses (IOLs) and more particularly to cartridges for use with devices use to inject IOLs into an eye.
The human eye in its simplest terms functions to provide vision by transmitting and refracting light through a clear outer portion called the cornea, and further focusing the image by way of the lens onto the retina at the back of the eye. The quality of the focused image depends on many factors including the size, shape and length of the eye, and the shape and transparency of the cornea and lens.
When trauma, age or disease cause the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. The treatment for this condition is surgical removal of the lens and implantation of an artificial lens or IOL.
While early IOLs were made from hard plastic, such as polymethylmethacrylate (PMMA), soft, foldable IOLs made from silicone, soft acrylics and hydrogels have become increasingly popular because of the ability to fold or roll these soft lenses and insert them through a smaller incision. Several methods of rolling or folding the lenses are used. One popular method is an injector cartridge that folds the lenses and provides a relatively small diameter lumen through which the lens may be pushed into the eye, usually by a soft tip plunger. The most commonly used injector cartridge design is illustrated in U.S. Pat. No. 4,681,102 (Bartell), and includes a split, longitudinally hinged cartridge. Similar designs are illustrated in U.S. Pat. Nos. 5,494,484 and 5,499,987 (Feingold) and 5,616,148 and 5,620,450 (Eagles, et al.). In an attempt to avoid the claims of U.S. Pat. No. 4,681,102, several solid cartridges have been investigated, see for example U.S. Pat. No. 5,275,604 (Rheinish, et al.) and 5,653,715 (Reich, et al.).
These prior art devices were intended to inject an IOL into the posterior chamber of an aphakic eye through a relatively large (approximately 3.0 mm or larger) incision. Surgical techniques and IOLs have been developed that allow the entire surgical procedure to be performed through much smaller incisions, 2.4 mm and smaller. Such small incisions require that the IOL be compressed very tightly, and that the nozzle used on the injection cartridge have very thin walls. The combination of a tightly compressed lens traveling through a very thin walled nozzle often results in the nozzle splitting during use.
Accordingly, a need continues to exist for an intraocular lens injection cartridge capable of injection an IOL through a relatively small incision.
The present invention improves upon prior art by providing a cartridge for an IOL delivery system that has a straight, thinned walled distal nozzle. The transition region between the tapered folding portion of the cartridge and the nozzle contains reinforcing gussets to help prevent splitting of the cartridge. Flow leaders in the nozzle direct the flow of material during molding at the 12:00 o'clock position, positioning the weld line of the flow front at the 6:00 o'clock position.
It is accordingly an objective of the present invention to provide a cartridge for a lens delivery system that has a straight, thinned walled distal nozzle.
It is a further objective of the present invention to provide a cartridge for a lens delivery system that contains reinforcing gussets to help prevent splitting of the cartridge.
Other objectives, features and advantages of the present invention will become apparent with reference to the drawings, and the following description of the drawings and claims.
As best seen in
Located on the proximal side of transition area 20, at the distal end of tapered portion 16 are raised flow leaders 26. Flow leaders 26 help direct the flow of material during injection molding of cartridge 10 to 12:00 o'clock position 28, then downwardly around straight portion 18, causing the weld line to form at 6:00 o'clock position 30. The inventors have surprisingly discovered that maximum stress in straight portion 18 occurs around 12:00 o'clock position 28, while minimum stress in straight portion 18 occurs around 6:00 o'clock position 30. Directing the weld line of the material flow to 6:00 o'clock position 30 places the weakest position of straight portion 18 at the location of minimal stress, thereby helping to reduce splitting of straight portion 18 during IOL injection.
While certain embodiments of the present invention have been described above, these descriptions are given for purposes of illustration and explanation. Variations, changes, modifications and departures from the systems and methods disclosed above may be adopted without departure from the scope or spirit of the present invention.
