Pulse extraction of ocular medical devices
AssigneeBausch & Lomb Incorporated
InventorsMadhu Ayyagari, Mahendra P. Nandu, Erik M. Indra, Alan J. Braun
Life of this patent
Estimating the term…
Abstract
A method of extracting residual materials from a polymeric, ophthalmic biomedical device, such as a contact lens, by using a mixture comprised of a primary solvent, such as carbon dioxide, and a polar co-solvent, such as isopropanol. By exposing the device to the co-solvent, the device expands. By pulsing or varying the concentration of the polar co-solvent in the mixture, the lens dimensions vary accordingly. When the lens is extracted while retained in a mold, the changes in lens dimensions causes the lens to be released from the mold.
Claims22
A method of extracting a polymeric, ophthalmic biomedical device comprising:
- (a) subjecting said device to a primary solvent;
- (b) subjecting said device to a mixture of a co-solvent and the primary solvent, for a predetermined period of time;
- and
- (c) subjecting said device to the primary solvent for a predetermined time such that said device is in a dry state,
- wherein said ocular medical device goes through at least one cycle of expansion and shrinkage.
A method of extracting a polymeric, ophthalmic biomedical device contained within a chamber, said method comprising:
- (a) subjecting said device to a supercritical fluid for a first predetermined time in said chamber;
- (b) introducing isopropyl alcohol into said chamber to obtain a first mixture including a first predetermined level of isopropyl alcohol and subjecting said device to said first mixture for a second predetermined period of time;
- (c) reducing the amount of isopropyl alcohol within said chamber to a second, lowered predetermined level and subjecting said device to the mixture for a third predetermined period of time;
- and
- (d) subjecting said device to supercritical fluid for a fourth predetermined time such that said lens is in a dry state,
- wherein said device goes through at least one cycle of expansion and shrinkage.
A method of extracting a contact lens retained in the mold in which it was cast, comprising:
- subjecting the lens to alternating concentrations of a supercritical fluid and a co-solvent, such that said contact lens goes through at least one cycle of expansion and shrinkage and whereby the contact lens is released from the mold.
A process of making a contact lens comprising:
- (a) casting said lens in a two-part mold assembly;
- (b) removing a first mold portion such that said lens is retained in a second mold portion;
- (c) extracting said lens with mixture of a supercritical fluid and a co-solvent and releasing said lens from said second mold portion;
- (d) subjecting said lens to the supercritical fluid, whereby a dry lens is obtained;
- (e) surface treating said dry lens such that at least one lens said surface is rendered hydrophilic;
- and
- (f) hydrating and packaging said lens.
A method of extracting an ocular medical device comprising, sequentially:
- (a) subjecting said device to a supercritical primary solvent, or a first mixture of a supercritical primary solvent and a co-solvent, in a chamber;
- (b) subjecting said device to a second mixture of the supercritical primary solvent and a co-solvent in the chamber, wherein the concentration of the co-solvent is higher than the first mixture;
- (c) reducing the level of the co-solvent in the chamber;
- (d) repeating steps (a) through (c);
- and
- (e) subjecting said device to the supercritical primary solvent to dry the device.
Dependencies are inferred from the claim text.