Mandrel for holding a lens blank and method of making a lens using the same
A mandrel for holding and positioning an intraocular lens blank during manufacturing includes a shank portion having a central axis and a lens blank holding section configured to hold the lens blank. The holding section includes a central cavity formed concentrically with the central axis of the mandrel. Projections are formed on a surface of the central cavity and are configured to support a first surface of the lens blank at a fixed distance from the surface of the central cavity. A ring fits within a peripheral portion of the central cavity to hold a second opposing surface of the lens blank. A method for making an intraocular lens using the mandrel includes filling the space formed under the first surface of the lens with a liquid, such as water, freezing the liquid, and then machining and/or milling the second surface of the lens blank.
1. A mandrel assembly for holding an intraocular lens blank, the mandrel assembly comprising:
a mandrel comprising:
a shank portion having a central axis, and
a lens blank holding section configured to hold a lens blank, the lens blank holding section including a central cavity formed concentrically with the central axis of the shank portion, the central cavity comprising a surface upon which projections are formed, and
a ring portion comprising an inner ledge, the mandrel assembly being configured such that, when said intraocular lens blank is held by said lens blank holding section and said ring portion is received within the central cavity, said projections contact and support a first bottom surface of the lens blank at a fixed distance from the surface of the central cavity and said inner ledge contacts and holds a second top surface of the lens blank opposing the first surface of the lens blank,
wherein the inner ledge of the ring portion is configured to hold the intraocular lens blank onto the mandrel by pressing down on the second top surface of the intraocular lens blank while the first bottom surface of the intraocular lens blank is supported by the plurality of projections of the mandrel,
wherein a space is formed between the first bottom surface of the lens blank and the surface of the central cavity as the lens blank is supported by the projections, and
wherein a hollow channel is formed within the central cavity, the hollow channel extending into the shank.
2. The mandrel assembly of claim 1 , wherein the shank portion is configured to be received within a supporting collet.
3. The mandrel assembly of claim 1 , wherein the mandrel further comprises a second cavity that is concentric with the central cavity and has a smaller cross-sectional diameter than the central cavity.
4. The mandrel assembly of claim 1 , wherein the ring portion is configured to be held within the lens blank holding section by an interference fit formed with a sidewall portion of the central cavity.
5. The mandrel assembly of claim 1 , wherein the ring portion further includes a plurality of holes formed along an inner peripheral surface thereof, the holes being configured to permit a liquid to be transferred into the space formed between the first surface of the lens blank as the lens blank is supported by the projections and the surface of the central cavity.
6. A method of making an intraocular lens, the method comprising:
providing a mandrel, the mandrel comprising:
a shank portion having a central axis, and
a lens blank holding section including a central cavity formed concentrically with the central axis of the shank portion, the central cavity comprising a surface upon which projections are formed;
positioning an intraocular lens blank in the central cavity of the mandrel;
providing a ring portion comprising an inner ledge;
fitting the ring portion to the mandrel such that the lens blank is held on the mandrel by said inner ledge contacting and holding a second surface of the lens blank and by said projections supporting a first surface of the lens blank at a fixed distance from the surface of the central cavity;
applying a liquid to a space formed between the first surface of the lens blank as the lens blank is supported by the projections and the surface of the central cavity;
freezing the liquid so that it supports the lens blank; and
forming a lens from the lens blank.
7. The method of claim 6 , wherein an optical center of the lens blank is positioned concentrically with the central axis of the mandrel shank.
8. The method of claim 6 , wherein the liquid comprises water.
9. The method of claim 6 , wherein forming the lens comprises milling and/or machining the second surface of the lens blank as it is supported within the mandrel.
10. The method of claim 6 , wherein the lens blank comprises a hydrophobic material.
11. The method of claim 6 , wherein forming the lens includes forming haptic portions of an intraocular lens.
12. The method of claim 6 , wherein the ring portion further includes a plurality of holes formed along an inner peripheral surface thereof, the holes being configured to permit a liquid to be transferred into the space formed between the first surface of the lens blank as the lens blank is supported by the projections and the surface of the central cavity.