Plastic and nonmetallic article shaping or treating: processes – Optical article shaping or treating – Nonmechanical aftertreatment
Reexamination Certificate
1999-02-18
2001-03-27
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Optical article shaping or treating
Nonmechanical aftertreatment
C134S025500, C134S901000, C264S233000, C264S344000, C425S445000, C425S446000
Reexamination Certificate
active
06207086
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for washing or hydration of ophthalmic devices.
BACKGROUND OF THE INVENTION
The molding of hydrophilic contact lenses is known. Various processes are disclosed in U.S. Pat. No. 4,495,313, to Larsen; U.S. Pat. No. 4,640,489 to Larsen, et al.; U.S. Pat. No. 4,680,336 to Larsen et al.; U.S. Pat. No. 4,889,664 to Larsen et al.; and U.S. Pat. No. 5,039,459 to Larsen et al., all of which are assigned to the assignee of the present invention.
These prior art references disclose a contact lens production process wherein each lens is formed by molding a reactive mixture in a lens mold, typically between a front curve (lower mold section) and back curve (upper mold section). The monomer injected in the molds is polymerized, thus forming a lens. The lens is typically subjected to a hydration bath, and then to multiple leaching steps which remove processing chemicals (leachable diluents and monomers) from the lens. The hydration bath removes the lenses from the front curve mold. Once demolded, the lens are advanced into a multi-step washing phase and then the lenses, while still wet, are removed from the washing phase and are packaged for consumer use.
In the earlier manufacturing processes for making contact lenses, the steps of hydration and diluent removal took place in large tanks. Hundreds of contact lenses were put in each tank and moved around the tank and then removed. By in-flow and out-flow streams, the tanks would be kept at a specified equilibrium level of diluent. There were several tanks with decreasing levels of diluent in which the contact lenses were soaked in sequence until they reached the equilibrium level of diluent. The contact lenses would be moved from one tank to the next until the level of diluent was below or at an acceptable level. Occasionally the tanks would be emptied for cleaning, and then refilled with clean water.
U.S. Pat. Nos. 5,080,839 and 5,094,609 disclose, respectively, a process for hydrating and washing contact lenses and a chamber for washing the contact lenses formed with a monomer or monomer mixtures of the type disclosed in the foregoing patents. The process disclosed in these patents was a significant advance; however, the transfer of lenses from the hydration phase to the washing step and the associated handling of the lenses resulted in the loss of some lenses. Plus, washing required large amounts of water and occurred in multiple soaking steps. The chamber holding the contact lens was filled with water, then after the contact lens and H
2
O reached equilibrium, the chamber was emptied and the steps were repeated.
As should be apparent, it would be desirable to make the hydration step more efficient, that is, to subject as many lenses as possible to hydration in the most efficient manner, using the least water possible.
BRIEF DESCRIPTION OF THE INVENTION
In accordance with the invention, a hydration and/or washing, e.g. diluent removal, apparatus and process is disclosed in which a plurality of device supporting members are provided preferably having one or more cavities each for containing an ophthalmic device, such as a contact lens and/or lens mold and/or reusable lens mold. The ophthalmic devices are arranged so that the hydration or cleansing fluid flows or is directed from contacting cleaner ophthalmic devices to contacting dirtier ophthalmic devices. The device supporting members can be arranged in any configuration so that the hydration or cleansing fluid contacts cleaner and then dirtier ophthalmic devices. The device supporting members can be arranged vertically: in-line like a column or like a stair-case, horizontally, helically or combinations of the above. For example, the fluid could flow horizontally from ophthalmic device to ophthalmic device on a first level of one or more device supporting members arranged horizontally and then flow vertically down and across to a second level of one or more device supporting members located beneath the first level, and then flow to a third level, etc. Alternatively, ophthalmic devices can be moved within a column in which the water falls like rain, or in a horizontal pipe through which a stream of fluid is pumped. Preferably the arrangement is at least partially vertical so that the hydration or cleansing fluid moves under gravity and does not have to be pumped. The hydration or cleansing fluid can be directed to move in a single stream from the cleanest ophthalmic device to the dirtiest ophthalmic device in the apparatus. Alternatively, the fluid can be directed to move in multiple streams from one or more of the cleanest ophthalmic devices to one or more of the dirtiest ophthalmic devices in the apparatus. The flow of fluid can be across ophthalmic devices and device supporting members or it can be through or both across and through the device supporting members. Preferably, multiple streams of the hydration or cleansing fluid can be directed to flow onto and across only ophthalmic devices in particular locations from clean to dirty ophthalmic devices in the apparatus. Preferably, the fluid flows across the device supporting members. If desired, additional fluid can be injected at one or more locations in the apparatus. The cleanest ophthalmic devices from the apparatus are removed at or near, that is in the vicinity of the input of clean hydration or cleansing fluid into the apparatus, and dirty ophthalmic devices are inserted into the apparatus preferably just before or in the vicinity of where the dirtiest hydration or cleansing fluid exits the apparatus.
The preferred hydration and/or washing apparatus and process comprises trays as the device supporting members. However, the device supporting members can have any configuration, which provides protection for and maintains the ophthalmic device but allows fluid to flow to, and around or over the ophthalmic device in or on the device supporting member, and then allows the fluid to flow out of the device supporting member. Other examples of device supporting members include a plastic cage, bowl, or the hydration and washing chambers for contact lenses used and disclosed in the prior art. It is further preferred that the device supporting member can be easily moved through the apparatus countercurrent to the flow of the fluid. In the preferred embodiment, the device supporting member is a lens supporting member, and the preferred lens supporting member is a tray. The preferred trays have a plurality of cavities each for containing an ophthalmic device, and preferably for containing a front curve mold with a contact lens in the mold. The following description will focus on the preferred embodiment involving the washing and hydration of contact lenses; however, other devices, particularly other ophthalmic devices may be substituted for the contact lenses in the description.
In the preferred embodiment, the trays are stacked vertically with the cavities (and lenses) in columns. The hydration or cleansing fluid, for example, de-ionized (DI) water, is injected or otherwise introduced into each of the cavities of the leading or upper tray. The fluid injected in each cavity flows downwardly through the stack of cavities of the column to wash over the lenses preferably in the front curve molds in the trays below the point where the fluid is injected. If desired, additional fluid also can be injected at one or more lower trays in the stack. In using the apparatus, a tray is inserted at the stack bottom, the stack is raised, and the uppermost tray in the stack is removed. The addition and removal of trays to the stack is carried out in a step-wise manner.
As lenses (in the trays) move upwardly in the stack, they encounter increasingly purer (less contaminated) hydration or cleansing fluid. The more contaminated fluid contacts the lenses at lower positions in the stack, but is still able to remove contaminants.
There is a counter-current effect, that is, the fluid flows downwardly in the apparatus and the trays with lenses move progressively upward. A vertical configur
Keene Darren S.
Kindt-Larsen Ture
Martin Wallace Anthony
Schlagel Mark E.
Johnson & Johnson Vision Care Inc.
Kiernan Anne B.
Vargot Mathieu D.
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