WO2002094543A2

WO2002094543A2 - Basket for holding a medical device

Info

Publication number: WO2002094543A2
Application number: PCT/EP2002/005620
Authority: WO
Inventors: Yasuo Matsuzawa; Lynn Cook Winterton; Michael Nelson Wilde
Original assignee: Novartis Ag; Novartis Pharma Gmbh
Priority date: 2001-05-23
Filing date: 2002-05-22
Publication date: 2002-11-28
Also published as: US8596782B2; ATE310634T1; DE60207554D1; WO2002094543A3; DE60207554T2; US20030024829A1; EP1395418A2; EP1395418B1

Abstract

A basket (100,200) for holding a medical device (10) has a lattice structure, wherein the lattice has a medical device contacting side and an opposite medical device non-contacting side and wherein the medical device contacting side of the lattice has sharp edges available for the medical device (10) to contact.

Description

Basket for holding a medical device

The present invention provides a basket for holding a medical device and a tray comprising a plurality of baskets for holding a plurality of medical devices, especially ophthalmic lenses. The basket or tray of the present invention is useful in the manufacture of medical devices, especially ophthalmic lenses, involving operations including but not limited to washing, extracting, coating and the like.

Many devices used in biomedical applications require that the bulk of the device have one property, while the surface of the device has another property. For example, contact lenses may have high oxygen permeability through the lens to maintain good corneal health. However, materials that exhibit exceptionally high oxygen permeability (e.g. polysiloxanes) are typically hydrophobic and will adhere to the eye. Thus, a contact lens generally has a core or bulk material that is highly oxygen permeable and hydrophobic, and a surface that has been treated or coated to increase hydrophilic properties, thereby allowing the lens to freely move on the eye without binding excessive amounts of tear lipid and protein.

In order to modify the hydrophilic nature of a relatively hydrophobic contact lens material, a coating may be applied onto the surface of a contact lens using a number of technologies, including a plasma treatment process, a Langmuir-Blodgett deposition process, a controlled spin casting process, a chemisorption process, a vapor deposition or a layer-by-layer polymer adsorption process.

The layer-by-layer polymer adsorption (LbL) process could be one useful process for increasing hydrophilic properties of contact lenses. By dipping iteratively one or more lenses in an alternating fashion to a polyanion (e.g., polyacrylic acid, PAA) solution and then a polycation (polyallylamine hydrochloride, PAH) solution, a LbL coating can be formed on the surfaces of lenses. A LbL coating on an ophthalmic lens can increase hydrophilic properties and thereby allow the lens to freely move on the eye without binding excessive amounts of tear lipid and protein. The on-eye movement is one of important criteria for wearing comfort.

Generally, LbL coating of lenses is carried out with the help of lens-carrying cages which each comprise male and female basket halves. Many such cages can be affixed together to form trays of baskets. Such trays may then be placed side-by-side to allow hundreds or thousands of lenses to be simultaneously processed with a coating solution. Such trays may also be used in other manufacturing processes of ophthalmic lenses, such as washing, extracting, coating, drying and the like.

Currently, various types of fixtures and baskets are used for holding lenses in those manufacturing processes. Generally, such baskets are made of a plastic but they can be made of any fabricated material. The structure of a basket can be a pair of half-spheres, which have curved surfaces to fit the curvature of an ophthalmic lens. The curved surface is not a solid blank piece. It is partially cut open so that a fluid such as washing solution, water, or extraction media, can freely pass through the basket while an ophthalmic lens is held in place. Currently available baskets with a lattice network structure generally have a percentage of opening surface over total surface being in the range of 25%-50%. This would give a sufficient fluid flow while holding the ophthalmic lens in place during a process.

However, those currently available baskets still have a relatively high percentage of solid surface available for a lens to contact. It is known that ophthalmic lenses may tend to stick to the solid surface of baskets under contact because of hydrophobic-hydrophobic interactions and/or bindings between surface oligomers. A high percentage of solid surface will be susceptible to the adhesion of a lens to a basket and prevent the lens from being treated uniformly during a washing, extracting, coating, or drying process. This could affect the efficiency of a process for treating lenses and therefore could be a problem for the production. Therefore, there is a need for a basket with a design that could minimize and/or eliminate the adhesion of a lens onto a basket.

Furthermore, when a lens-holding basket or tray is used in a LbL coating process, some chemicals such as polyelectrolytes tend to adhere onto the surface of the basket or tray to form an unwanted coating. Such coating on the basket or tray becomes thicker and brittle as the basket is repeatedly used in LbL coating process. It is very likely that this unwanted coating will flake or fracture off from the basket surface during a LbL coating process. If flakes of the unwanted coating adhere onto a lens to be coated, they can mask some portions of a lens and preventing those portions of lenses from being coated, producing lenses with coating defects. To eliminate this undesirable phenomenon occurring, the unwanted LbL coating needs to be abraded using a physical means. Such physical removal process of the unwanted LbL coatings from baskets is long, tedious and labor intensive and may damage the surfaces of the baskets. Therefore, there is a need for a method of efficiently removing any unwanted coatings on baskets.

An object of the invention is to eliminate such problems by providing an essential "contactless" surface of baskets to ophthalmic lenses.

Another object of the invention is to provide a method for cleaning efficiently baskets or trays containing baskets to remove any unwanted coatings from the surfaces of the baskets or trays without damaging their surfaces.

An embodiment of the present invention is a basket for holding a medical device. A basket of the present invention has a lattice structure having a medical device-contacting side and an opposite medical non-contacting side, wherein the medical device-contacting side of the lattice has sharp edges available for the medical device to contact. In a preferred embodiment, the sharp edges are thin lines. More preferably, each of the lines has a thickness of about 1/10 mm or less.

Another embodiment of the present invention is a tray comprising a plurality of baskets, wherein each of the basket is capable of holding a medical device and has a lattice structure having a medical device-contacting side and an opposite medical device non- contacting side, wherein the medical device-contacting side of the lattice has sharp edges available for the medical device to contact. In a preferred embodiment, the sharp edges are thin lines. More preferably, each of the thin lines has a thickness of about 1/10 mm or less.

Still another embodiment of the invention is a stack tray assembly for holding medical devices, e.g. ophthalmic lenses, comprising a plurality of such trays, each tray comprising a plurality of baskets, the baskets each having a lattice structure, wherein the lattice has a medical device contacting side and a medical device non-contacting side, and wherein the medical device contacting side of the lattice has sharp edges available for the medical device to contact. Still another embodiment of the present invention is a method for cleaning a basket for holding a medical device or a tray comprising a plurality of such baskets for holding a plurality of medical devices , the method comprising immersing the basket or the tray in an aqueous solution containing at least 1 % weight/volume of KOH or NaOH for at least 5 minutes, removing the basket from the aqueous KOH or NaOH solution, and rinsing the basket with water to remove KOH or NaOH from the surface of the basket.

Further advantageous embodiments of the invention become apparent from the following description of preferred embodiments of the invention with the aid of the drawings in which:

Figure 1 is a schematic presentation of the female member of a basket for holding an ophthalmic lens according to a preferred embodiment of the invention. Figure 1a is the bottom view (the lens-non-contacting side) of the female member and Figure 1 b is the top view (the lens-contacting side) of the female member,

Figure 2 is a schematic presentation of the male member of a basket for holding an ophthalmic lens according to a preferred embodiment of the invention. Figure 2a is the bottom view (the lens-contacting side) of the male member and Figure 2b is the top view (the lens-non-contacting side) of the male member,

Figure 3 is a section view of a basket according to a preferred embodiment of the invention,

Figure 4 is a cutaway view showing lens position between the male and female members and corresponding tolerance in a basket according to a preferred embodiment of the invention,

Figure 5 is a schematic presentation of a portion of a tray containing male members of baskets (bottom view) according to a preferred embodiment of the invention,

Figure 6 is a schematic presentation of a portion of a tray containing male members of baskets (top view) according to a preferred embodiment of the invention,

Figure 7 is a schematic presentation of a portion of a tray containing female members of baskets (top view) according to a preferred embodiment of the invention, Figure 8 is a schematic presentation of a portion of a tray containing female members of baskets (bottom view) according to a preferred embodiment of the invention

and

Figure 9 is a schematic presentation of a support capable of holding female or male members of baskets for holding ophthalmic lenses.

The present invention, in one aspect, relates to baskets for holding medical devices. The basket of the present invention has a lattice structure, which has a medical device contacting side having sharp edges available for a medical device to contact and an opposite medical device non-contacting side. The baskets are useful in a manufacturing process such as washing, extracting, drying, plasma coating, LbL coating or the like, during the production of medical devices. The baskets have particular utility in the LbL coating of medical devices, especially ophthalmic lenses.

As used herein, "a medical device" refers to a device having surfaces that contact tissue, blood, or other bodily fluids of patients in the course of their operation or utility. Exemplary medical devices include: (1 ) extracorporeal devices for use in surgery such as blood oxygenators, blood pumps, blood sensors, tubing used to carry blood and the like which contact blood which is then returned to the patient; (2) prostheses implanted in a human or animal body such as vascular grafts, stents, pacemaker leads, heart valves, and the like that are implanted in blood vessels or in the heart; (3) devices for temporary intravascular use such as catheters, guide wires, and the like which are placed into blood vessels or the heart for purposes of monitoring or repair; and (4) ophthalmic lenses. In a preferred embodiment, medical devices are ophthalmic lenses.

"An ophthalmic lens", as used herein, refers to a contact lens (hard or soft), an intraocular lens, or an aesthetic lens to change eye color. An ophthalmic lens generally has first and second optical surfaces. As used herein, "a basket" refers to an assembly that comprises two or more members and a means for securing the members together to form a cavity for receiving a medical device, all members having openings for allowing fluid to pass through the basket while the medical device is in place. Preferably, a basket of the present invention comprises a first member and a second member and has a percentage of opening surface over total surface being at least 25%.

Baskets can be made from any easily fabricated material, including, without limitation, plastics, metal, ceramic, glass or similar materials. Preferably, the members of the baskets are made from a plastic material. Examples of suitable plastic materials include polystyrenes, polyolefines, acrylics, polycarbonates, polyacetal resins, polyacrylethers, polyacrylether sulfones, nelons, and the like. The most preferred material for the members of a basket is polycarbonate which can be machined or injection molded and can withstand the solvents and washing and coating solution within the temperature range utilized.

The shape of a basket is preferably designed to accommodate the shape of a medical device to be held.

In a more preferred embodiment of the present invention, the basket for holding an ophthalmic lens comprises a pair of mating members (i.e., a female member and a male member), and a means for securing the members together to form a cavity for receiving the ophthalmic lens. Such cavity inhibits inversion or rolling over of the ophthalmic lens when an ophthalmic lens is in place. In an even more preferred embodiment of the invention, the male member can be inserted within the female member such that there is clearance for an ophthalmic lens between the two members, yet not enough so that the ophthalmic lens can invert or roll over. In a particularly preferred embodiment, there are through-holes in the centers of the female and male members, and the sharp edges available for an ophthalmic lens to contact are radial lines without nodes. Such radial lines without nodes can provide a minimal surface available for an ophthalmic lens to temporarily or permanently contact.

Figures 1 and 2 schematically represent the female (100) and male (200) members of a basket for holding a contact lens according to a preferred embodiment of the invention. Through-holes (101, 201) are cut in the centers of the female and male members. The lens- contacting sides of both mating members are designed to have edges of radial lines without nodes. Such radial lines without nodes are only surface areas in a basket available for an ophthalmic lens to contact. Figures 3 and 4 schematically depict an assembly (basket) of the female member (100) and the male member (200). The ratio of open area to total surface area is calculated to be 80%, based on a projected flat surface pattern of the basket shown in Figures 1 -4. A basket with such design can minimize the surface area onto which the lens can stick and still maintain a sufficient mechanical strength.

Referring to Figure 4, a lens (10) is located in a cavity (410) formed by mating the female member (100) and the male member (200). The cavity (410) has clearance for a lens (10) between the two members, but not enough for the lens (10) to invert or roll over when the lens is placed therein.

An advantage of using a basket of the invention is thai: the adhesion of an ophthalmic lens to any part of the basket can be minimized and/or eliminated probably because there is not sufficient surface area with which a lens could maintain a permanent contact. By using baskets of the invention, ophthalmic lenses can be treated uniformly during a manufacturing process such as washing, extracting, coating, drying and the like, especially during a LbL coating process.

The present invention, in another aspect, relates to a tray for holding a plurality of medical devices, preferably ophthalmic lenses. A tray of the invention is useful for carrying out a process, such as washing, extracting, coating, drying and the like, particularly LbL coating, on batches containing a plurality of medical devices. Thus, the efficiency and productivity of the processing of medical devices, preferably ophthalmic lenses, can be substantially enhanced by using trays of the invention.

"A tray" as used herein refers to a assembly holding a plurality of baskets. A plurality of baskets can be intrinsic parts of a tray, or can be assembled together by one or more support members. "Support members" means any structural elements which together can hold a plurality of baskets. A plurality of baskets can be arranged in any way, for example, in rows or a matrix, in a tray. Pref erably, a tray of the invention comprises a first tray portion which holds the first members of a plurality of baskets, a second tray portion which holds the second members of the plurality of basket and a securing means for securing the first and second tray portions together to form the plurality of baskets for holding a plurality of medical devices.

More preferably, a tray of the invention comprises a first portion which holds the male members of a plurality of baskets, a second tray portion which holds the female members of the plurality of basket and a securing means for securing the first and second tray portions together to form the plurality of baskets. Each of the male members can be inserted within one female member such that there is clearance for an ophthalmic lens between the two members, yet not enough so that the ophthalmic lens can invert or roll over when emplaced therein.

Trays of invention can be made from any easily fabricated material, including, without limitation, plastics, metal, ceramic, glass or similar materials, preferably from a plastic material. Examples of suitable plastic materials include polystyrenes, polyolefines, acrylics, polycarbonates, polyacetal resins, polyacrylethers, polyacrylether sulfones, nelons, and the like. The most preferred material for making trays is polycarbonate which can be machined or injection molded and can withstand the solvents and washing and coating solution within the temperature range utilized.

Figures 5-8 schematically illustrate the two mating portions of a tray for holding ophthalmic lenses according to an preferred embodiment of the invention. A plurality of male basket members (200) are held by a first support shown schematically in Figure 9. A plurality of female basket members (100) are held by a second support. The two mating portions of a tray are secure together by securing means through openings 901, 902, 903 and 904 in the supports. A matrix of through-holes in the support shown in Figure 9 are used to secure female or male basket members. Openings 911, 912, 913 and 914 in the supports can be used in the securing of a plurality of trays to form a stack assembly.

The present invention, in still another aspect, relates to a stack assembly for holding medical devices, preferably ophthalmic lenses. The stack assembly of the invention comprises two or more trays of the invention and a stacking means for stacking together the trays. By using a stack assembly of the invention, large numbers of medical devices, preferably ophthalmic lenses can be processed simultaneously in a manufacturing process such as washing, extracting, coating, drying and the like, resulting in a high though-put efficiency of the manufacturing process.

The present invention, in a further aspect, relates to a method for cleaning baskets or trays or a stack assembly for holding medical devices, preferably ophthalmic lenses. The method of the invention comprises immersing the baskets or the trays or the stack assembly in an aqueous solution containing at least 1 % weight volume of KOH or NaOH for at least 5 minutes, removing the basket from the aqueous KOH or NaOH solution, and rinsing the basket with water to remove KOH or NaOH from the surface of the basket.

By using the cleaning method of the invention, even very dried, thick LbL coatings on baskets or trays can be removed without any scrubbing. This simple process allow to provide the baskets or trays with clean surfaces for every LbL coating runs.

In order to better enable the reader to understand specific embodiments and the advantages thereof, reference to the following non-limiting examples and drawings is suggested.

Example 1

(1) Synthesis of Macromers

Silicone-containing macromers, which are used in making contact lenses, are synthesized according to the procedures described in Example B-1 to B-4 of US-A- 5,849,811 , herein incorporated by reference in its entirety.

(a) Production of contact lenses

Contact lenses are prepared according to the procedures described in Example B-5 to B-14 of US-A-5,849,811. Example 2

This example illustrates the comparison of the performance of a basket (Line contact) of the invention with two types of baskets (types I and II) in layer-by-layer (LBL) coating process. Types I and II baskets both are conventional designs. Type I baskets have holes to allow liquid pass through the baskets. In order to have a suitable mechanical strength, type I baskets have a small percentage of open area over total surface. Type II baskets have holes to allow liquid to pass through the baskets and small bulges uniformly distributed on the lens contacting solid surface. Those small bulges provide direct lens support and can decrease lens-accessible surface area and may facilitate the movement of lens in the baskets.

LbL coatings on contact lenses are carried as follows. A contact lens held in one of three type of baskets is dipped first into a polyacrylic acid (PAA) solution and then into a polyallylamine hydrochloride (PAH) solution. The time for coating the first layer of PAA is about five minutes. The time for coating the second and subsequent layers of PAH and PAA is also about five minutes. A rinsing step may be carried out between the dips in the first and second coating solutions. This procedure of dipping in an alternative fashion into the PAA solution and PAH solution is repeated 4 times. A final layer of PAA is coated on the lens. The coated lenses containing nine LbL layers

(PAA PAH/PAA/PAH/PAA/PAH/PAA/PAH/PAA) are then released into a releasing and storage medium (e.g., pure water or a saline solution) where the coated lenses are stored.

After coating, dye stain tests are carried out to check if the lenses are uniformly and completely coated with LbL layers. A suitable amount of a dye, e.g., Sudan Black, is dissolved in vitamin E oil. Sudan Black is a hydrophobic dye and has a great affinity to silicone elastomers. Sudan Black can stain uncoated contact lenses to be tested. If contact lenses are coated uniformly and completely, the coated lenses have a hydrophilic coating that prevents Sudan Black from penetrating onto and into lenses and thereby from staining lenses. Any observed staining on a lens indicates failure in its LbLcoating.

Table I shows the results obtained for three types of baskets. The basket with a line contact design has a lowest failing rate Table-I Effects of basket designs on the efficiency of LBL coating of lenses

surface pattern of each basket.

² The failing rate is equal to the number of lenses failed divided by the number of total lenses tested in a group.

* No agitation during the LBL coating.

Claims

1. A basket (100,200) for holding a medical device (10), the basket having a lattice structure, wherein the lattice has a medical device contacting side and an opposite medical device non-contacting side and wherein the medical device contacting side of the lattice has sharp edges available for the medical device (10) to contact.

2. A basket according to claim 1 , wherein the sharp edges are thin lines.

3. A basket according to claim 2, wherein each of the thin lines has a thickness of about 1/10 mm or less.

4. A basket according to any one of claims 1 to 3, wherein the medical device (10) is an ophthalmic lens, wherein the basket comprises a first (100) and a second (200) mating members, said first (100) and second (200) mating members forming a cavity (410) when mated for receiving the ophthalmic lens (10), said cavity inhibiting inversion or rolling over of the ophthalmic lens (10) when emplaced therein.

5. A basket according to claim 4, wherein the first mating member (100) is capable of being inserted within the second mating member (200).

6. A basket according to claim 4 or claim 5, wherein the lens-contacting side of the second mating member (200) has a concave curvature.

7. A basket according to any one of claims 4 to 6, wherein the lens-contacting side of the first mating member (100) has a convex curvature.

8. A basket according to any one of claims 4 to 7, wherein the thin lines are radiating from the centers of the first (100) and second (200) mating members and wherein there are through-holes (101,201) in the centers of the first (100) and second (200) mating members.

9. A tray for holding a plurality of medical devices (10), comprising a plurality of baskets (100,200) according to any one of claims 1 to 8.

10. A stack tray assembly for holding medical devices (10), comprising a plurality of trays according to claim 9.

11. A method for cleaning baskets (100,200) according to any one of claims 1 to 8 or a tray according to claim 9, the method comprising immersing the baskets (100,200) or the tray in an aqueous solution containing at least 1 % weight volume of KOH or NaOH for at least 5 minutes, removing the baskets (100,200) or the tray from the aqueous KOH or NaOH solution, and rising the baskets (100,200) or the tray with water to remove KOH or NaOH from the surface of the baskets (100,200) or the tray.