FR2801986A1 - Culturing of cells, particularly neuronal cells, useful for transplantation for treating neurological disorders such as Parkinson's disease or for gene therapy - Google Patents

Abstract

A method of culturing cells comprises proliferating precursor cells, by incubating them in proliferating medium which includes basic fibroblast growth factor (bFGF), and differentiating the precursor cells, by incubating them in an incubation vessel which contains differentiation medium, to form a reaggregation of differentiated cells not adhered to any surface of the incubation vessel. Independent claims are also included for the following: (1) a method of culturing cells comprising incubating the cells in proliferating medium which includes bFGF; (2) a method of culturing differentiating cells, comprising incubating precursor cells in an incubation vessel which contains differentiation medium to form a reaggregation of differentiated cells that are not adhered to any surface of the incubation vessel; (3) a method of treating a patient with neurological disorder comprising: (a) culturing differentiated neuronal cells, the culturing comprising the novel method; and (b) administering the differentiated neuronal cells to a patient; (4) a method of introducing a gene product into a brain of a patient comprising: (a) transforming neuronal precursor cells; (b) culturing the transformed neuronal cells, the culturing comprising the novel method; and (c) administering the differentiated transformed neuronal cells into a patient; (5) an assay for a substance comprising: (a) culturing differentiated neuronal cells, the culturing comprising the novel method; (b) exposing the differentiated neuronal cells to the substance; and (c) observing the effect of the substance on the differentiated neuronal cells; and (6) a cell culture comprising 80-95% differentiated neuronal cells and less than 5% glial cells.

Description

The present invention relates to improvements made to

  lenses with variable focal length, in particular those intended to be used for glasses. Although there are many uses for variable focal length lenses, there is a particular need for these lenses as spectacle lenses. This necessity arises since, when people age (generally after the age of 45), the lens present in the human eye becomes incapable of achieving sufficient accommodation to focus on close objects. After the discovery of this state of limited focal accommodation, designated by the term presbyopia, a single set of fixed focus glasses proved unsatisfactory for far and near vision,

  regardless of the general visual acuity of the wearer of the glasses.

  Whatever prescription (if there is one) that may be required to correct a person's vision based on distance, an additional value of optical power (up to three diopters) has been found necessary to correct a person's vision of nearby objects. The required "proximity additive system" generally does not contain any astigmatic component even if the wearer needs a correction

astigmatism for sight from afar.

  Numerous patents, which describe lenses or lenses with variable focal length filled with liquid, have been filed in the last hundred years. One such patent, US Patent No. 5,138,494 to Stephen Kurtin, describes a variable focal length lens, which includes a transparent extensible membrane spaced from a lens, the space between these elements being filled with a liquid having an index relatively high refraction. As further described in this patent, the peripheries of the rigid lens and the membrane are connected by a flexible sealing element. The rigid lens, the membrane and the sealing element define an essentially fixed volume for filling with a liquid. The modification of the spacing between the membrane and the rigid lens in such a structure causes a deflection of the membrane, which increases the power of the lens or decreases it, depending on the direction of change of the spacing. If the periphery of the membrane is circular, its distended surface is essentially spherical, and a slight distortion appears or no optical distortion appears during use. However, for questions of style, it is frequently desired to have forms of glasses other than circular. It has been found that when the lens is made with a more or less circular shape, the shape of the membrane can differ greatly from the desired spherical shape, and optical deformations can be encountered which are

  greater than is desirable.

  This problem has been addressed by the authors of the present invention in US Patent No. 5,668,620, which describes means for ensuring spherical extension of the membrane regardless of the peripheral shape of the lens. The desired result is obtained by the fact that there is provided a membrane support member which supports the membrane so that the free (unsupported) area of the membrane is essentially circular at all times. Lenses formed

  in accordance with the description contained in patent 5,668,620 present

  excellent optical properties, that is to say that there is a very low

  optical distortion with respect to the required range of optical powers.

  However, when such a lens is seen by an outside observer, the line of intersection between the free surface of the membrane and the membrane support member may be visible and may therefore give the lens an unpleasant appearance of the point. from an aesthetic point of view. The visual contrast between the shape of the membrane surface in the region outside the free area of the membrane and the shape of this surface in the free area can also contribute to altering the appearance.

aesthetic.

  It is therefore an object of the present invention to provide variable focal lenses filled with a liquid, of the type comprising an extensible membrane supported by a membrane support element, in which the intersection between the free zone of the membrane and the element of

  membrane support is not detectable visually.

  Another object of the present invention is to provide variable focal lenses filled with a liquid of the type having an expandable membrane supported by a membrane support member, wherein the visual contrast between the supported surface of the membrane and the surface

  unsupported membrane is reduced.

  Another object of the present invention is to provide variable focal lenses filled with liquid comprising expandable membranes, in which the optical distortion usually caused by a periphery

non-circular is reduced.

  This problem is solved according to a first aspect of the invention using a lens with variable focal distance, characterized in that it comprises: - a rigid lens; - a membrane support element, arranged across and inside the field of vision of said rigid lens while being spaced therefrom, said membrane support element comprising a toroidal surface, which comprises means for support for supporting a transparent extensible membrane; - a transparent extensible membrane placed under a radial tension and arranged across the field of vision of said rigid lens and placed against said surface of toroidal form, the tension in said membrane causing the latter to be applied against said surface of toroidal form; - a transparent liquid filling the space between said rigid lens and said membrane; - flexible sealing means serving to retain said transparent liquid between said rigid lens and said membrane; and - means producing a variable spacing making it possible to adjust the spacing between said membrane support element and said

rigid lens.

  According to another characteristic of the invention, said toroidal surface has a cross-sectional shape which corresponds to

a regular convex curve.

  According to another characteristic of the invention, said convex curve

  regular is essentially an arc.

  According to another characteristic of the invention, the radius of said arc is

  between approximately 0.51 cm and approximately 5.1 cm.

  According to another characteristic of the invention, a central region of said membrane support element is transparent and has

  essentially the same refractive index as said transparent liquid.

  According to another characteristic of the invention, said membrane support element and said rigid lens are connected in a hinged manner and that said means producing variable spacing act so as to modify the space between said support support element. membrane and said rigid lens, at points distant from

said hinge.

  According to another characteristic of the invention, said toroidal-shaped surface has a cross-sectional shape which is a

solid convex curve.

  According to another characteristic of the invention, said convex curve

  united is essentially an arc.

  According to another characteristic of the invention, the radius of said arc is

  between 0.51 cm and about 5.1 cm.

  According to a second aspect, the invention relates to a lens with variable focal distance, characterized in that it comprises - a rigid lens; - a membrane support element, arranged across and inside the field of vision of said rigid lens while being spaced from the latter, said membrane support element comprising a membrane support surface; - means providing variable spacing for adjusting the spacing between said membrane support member and said rigid lens between a first spacing and a second spacing; - a transparent extensible membrane disposed across the field of vision of said rigid lens and having a first surface in contact with said support surface of the membrane, and a second surface released from said support surface of the membrane, the periphery of said second surface being tangent to said surface supporting the membrane, and this for all the spacings between said first spacing and said second spacing - a transparent liquid filling the space located between said rigid lens and said membrane; - flexible sealing means serving to retain said liquid

  transparent between said rigid lens and said membrane.

  According to another aspect of the invention, the invention relates to a lens with variable focal distance, characterized in that it comprises - a rigid lens; - a membrane support element, arranged across and inside the field of vision of said rigid lens and being spaced therefrom, said membrane support element comprising a radially curved surface, which comprises support means serving to support a transparent extensible membrane; a transparent extensible membrane placed across the field of vision of said rigid lens and placed against said radially curved surface, said transparent extensible membrane being in contact with said radially curved surface, for all the spaces existing between said membrane support element and said rigid lens; - a transparent liquid filling the space between said rigid lens and said membrane; - flexible sealing means serving to retain said transparent liquid between said rigid lens and said membrane; and - means producing variable spacing to adjust the spacing between said membrane support member and said

rigid lens.

  In the case of a lens arranged in accordance with the teachings of patent N 5 668 620, the free part of the membrane (that is to say the interior part of the circular opening in the membrane support element) is flat or slightly spherical, while the part of the membrane situated outside the opening can be conical and has a relatively sloping inclination. Both an abrupt change in the slope of the membrane at the periphery of the free area of the membrane, and a difference in the characteristics of the surfaces on either side of this edge have been found to be undesirable from the point of view

  aesthetic. In the description given below we will describe means

  to reduce these two unwanted features. This is obtained by conformation of the surface of the support element of the membrane, against which the membrane is applied, in the form of a part of a torus having an approximately circular cross section, and by bringing the periphery of the free surface of the membrane to be tangent to the surface of the support element, which allows a smooth transition to be achieved with

  the free zone without sudden variations in the slope.

  Other features and advantages of the present invention

  will emerge from the description given below taken with reference to the drawings

  attached, in which: - Figure 1 is a rear view (that is to say from the side of the wearer) of part of a pair of glasses using glasses in accordance with a first embodiment of the present invention; - Figure 2A is a partial cross-sectional view of one of the spectacle lenses shown in Figure 1, taken along line 2-2 in Figure 1; and - Figure 2B is a view similar to the view of Figure 2A, but

  showing another structure of the membrane support member.

  Figure 2B is seen along line 2-2 in Figure 1.

  Figure 1 shows part of a pair of glasses which comprise lenses or lenses with variable focal length according to the present invention. The right lens is shown (the Figure being seen from the side of the wearer's glasses) plus a small part of the adjustment tab (19 ') of the left lens, sufficient to

  show the relationship between the elements. The following description refers to

  generally only one glass, but naturally

  will understand that there are actually two glasses in a telescope.

  Although from an optical point of view it can be considered that a single lens, a lens or a lens with variable focal length 21 of the type according to the invention can be envisaged as an assembly comprising a rigid fixed lens plus a liquid lens which has a power variable. The liquid lens is delimited on one side by the rigid lens and on the other side by an extendable transparent membrane, the space between the membrane and the rigid lens being filled with a transparent liquid. If the rigid lens is brought closer to the membrane, the membrane expands and becomes more and more convex, which increases the optical power of the lens and consequently of the whole of the lens. Conversely, if the rigid lens is moved away from the membrane, the membrane becomes less convex or less

  concave, which reduces the optical power of the whole.

  As can be seen in Figure 1, the glasses include a frame 10 to which are attached the arms (not shown). The frame generally has a symmetrical shape with respect to a nasal region 10 '. A pair of sets of glasses 11 'and 11' (one set on the right and one set on the left) are fixed to the frame 10, on each side of the nasal region 10 ', by means of the use of screws or other means (not shown). Only the adjustment tab 19 ′ of the left-hand assembly 11 ′ is visible in FIG. 1, the spectacle lens assembly 11 ′ being the symmetrical of the assembly 11. The assemblies formed by the spectacle lenses are positioned so that the wearer's left eye sees through the assembly 11 'and his right eye sees through

the set 11.

  An extensible membrane 15 is joined to the retaining device 23 while being placed under radial tension, and the resulting sub-assembly is fixed to the front ring 14, a membrane support element 16 being retained between the retaining device and the seal 13. The central part of the membrane support element 16, that is to say the region

  located inside the retainer 23, is preferably trans-

  parent. The membrane support member can have any

  desired peripheral shape; but regardless of its peripheral form

  rique, the part 16 ', of its upper surface against which the membrane 15 is applied, has a toroidal shape, that is to say that it constitutes a part of a torus. This part of the support element preferably has a radially curved surface; its cross-sectional shape preferably approximates an arc of a circle (having a radius R). The surface of the membrane 15 inside its line of contact 16 "with the membrane support element 16 (the free surface of the membrane) is free to tension as will be described below. The shape the convex curved toroidal of the membrane support element 16 leads to the fact that the contact line 16 "is essentially circular, and in that the membrane is held tangent to the toroidal surface at the level of the contact line. When the membrane 15 is extended to reduce the focal distance of the assembly formed by the spectacle lens and therefore its optical power increases, the contact line 16 "(ie the line of tangency) moves outward but remains circular.

  extended line of the membrane therefore remains spherical.

  The specific value of the radius R is not critical, but the preferred values are within certain limits for each application of the invention. The limits for a particular application depend mainly on the extent and the variation of the "span" between the contact line 16 "and the stepped stage part 16" ". It is preferable that the radius i15 R is large enough so that the membrane is in contact with the surface 16 'at or near the stepped part 16 "", for the widest part (almost at the point where the tongue 19 is located for the glass shown in Figure 1) And preferably it should be sufficiently small so that, when the membrane is extended as far as possible outwards, the circle defined by the contact line 16 "does not reach the stepped part 16" ", at the level of the part the narrowest (at the top of the glass shown in Figure 1). For ophthalmic lenses, optimal values of R are usually between about 0.51 cm and about 5.1 cm, but values outside these limits may be desirable in some cases. The cross-sectional shape of the toroidal surface need not be an arc since the large deviation from the circular state can still provide the properties which provide the difference in curvature between this circle and the free surface of the membrane, which is not visually detectable by an outside observer. Even if the shape of the surface of the membrane support element in contact with the membrane is not an arc of a circle, it is preferably a regular convex curve, in particular near the line of contact 16 ", so that it is invisible. A rigid lens 12 is joined or otherwise fixed to a rear ring 17, which is separated from the front ring 14 by hinges

  22 and an actuator 20. The actuator 20 is used to modify the space

  ment between the lens 12 and the membrane 15. Since means for adjusting the spacing are old and not part of the present invention, these elements are shown only in Figure 1; more details can be obtained by referring to patent application US Serial 08/226334. Examples of other mechanisms for assuming this function can be found by referring to patent application US N of series 08/336170 filed by the authors on the basis of the

present invention and others.

  A flexible seal 13, preferably formed of a

  durable elastomer, extends between the rear ring 17 and the front ring 14.

  The space inside the seal 13, the membrane 15 and the rigid lens 12 is filled with a transparent liquid 21, preferably having a refractive index close to that of the membrane 14, of the rigid lens 12 and the membrane support member 16, and all preferably have the same or almost the same refractive index. The observation of the membrane support element 16 as shown in FIG. 1 takes place through the rigid lens 12. If, as is preferred, the membrane support element, the membrane and the liquid transparent filling, all have substantially the same refractive index, that it is difficult or impossible to see the membrane support element. However, to have a clear understanding of the preferred arrangement of the invention, there is shown in Figure 1, the inner periphery 16 "'of this element, as well as the stepped part 16" ", as if these details were clearly visible. The contact line 16 "between the free surface of the membrane 15 and the membrane support element 16 is represented in the form of a line represented by

  dashes in Figure 1, although it is also not visible.

  An adjustment tab 19 is fixed to the rear ring 17 and extends

  outwards from this ring, at a point distant from the hinges.

  The adjustment tabs 19 and 19 ′ starting from the lenses of the glasses, (as can be seen in FIG. 1) mesh with an actuator 20 situated just above the nose of the wearer. The actuator 20 allows the wearer to adjust the distance between each front ring 14 and the corresponding rear ring 17 at points adjacent to the actuator. This results in a variation of the angle between the front ring 14 and the rear ring 17, by modifying the volume between the planes of these two rings. A flexible seal 13 is arranged so that the change in volume due to its movement is relatively small. Since the liquid 21 is substantially incompressible, the membrane 15, the most flexible element containing the liquid expands as necessary so as to enclose a fixed liquid volume. The movement of the adjustment tab 19 towards the frame 10 causes the membrane 15 to bulge outward, which leads to a convex membrane surface and to a

increased optical power.

  Assuming that the refractive index of the liquid 21 is equal to that of the rigid lens 12, the optical power of the lens assembly is determined by the refractive index and by the shapes of the membrane 15 and the surface exterior (rear) of the rigid lens 12. The shape of the gap between the liquid 21 and the lens 12 has no effect. The rear surface of the rigid lens 12 is usually ground, so that when the adjustment tabs 19,19 'are in their rearmost position, each set of variable focus lenses has optical power (including any correction astigmatism required), which allows the wearer to focus on distant objects. If the wearer does not need any correction in the far view, the rigid lens 12 can be simply a piece of plastic or flat glass (i.e. a lens having zero optical power). A rotation of the actuator 20 aimed at bringing the adjustment tabs 19 and 19 ′ towards the frame 10 has the effect that the membrane expands and becomes convex, which increases the optical power of the lens assembly so that the wearer can focus on

closer objects.

  By arranging the surface of the membrane support member 16 as part of a united convex torus, the periphery of the free surface of the membrane remains substantially circular and tangent to the toroidal surface when the membrane expands. Therefore, the free surface of the

  membrane is spherical and no optical distortion is introduced.

  At the same time, as seen by an outside observer, the difference in shape between the free surface of the membrane and the surface of the membrane supported by the membrane support member is not visually detectable. Figure 2B shows another embodiment of the membrane support member. The membrane support member 26 of Figure 2B is identical to the membrane support member 16 of Figure 2A except that the region of the support member within the innermost line of contact between the membrane and the membrane support member is cut to form a conical surface 36. A potential advantage of this construction is that if the index matching between the transparent liquid 21 and the membrane support member 16 is less than a perfect value, the reflections on the surface 36 of FIG. 2B are visible to an outside observer, in a smaller range of viewing angles than for reflections produced by the surface of

  the membrane support member 16 between 16 "and 16" 'in Figure 2A.

  This is why with small mismatches of the indices, intense reflections appear only in a narrow range of angles of refraction near the grazing incidence, and consequently the curved surface of the support element of the membrane, represented. in Figure 2A, shows a region with intense reflections occupying a

  relatively wider viewing angle.

Claims (26)

R E V E N D I C A T I ONS   1. Lens with variable focal length, characterized in that it comprises: - a rigid lens (12) - a membrane support element (16), arranged across and inside the field of vision of said rigid lens while being spaced therefrom, said membrane support member comprising a toroidal surface (16 '), which includes support means for supporting a transparent expandable membrane; - a transparent extensible membrane (15) placed under a radial tension and disposed across the field of vision of said rigid lens and placed against said toroidal surface (16 ′), the tension in said membrane causing the latter to apply against said toroidal surface; - a transparent liquid (21) filling the space between said rigid lens and said membrane (16); - flexible sealing means (13) serving to retain said transparent liquid between said rigid lens and said membrane; and means (20) providing variable spacing for adjusting the spacing between said membrane support member and said rigid lens.   2. Variable focal length lens according to claim 1, characterized in that said toroidal surface (16 ') has a   cross-sectional shape which is a regular convex curve.   3. Variable focal length lens according to claim 2, characterized in that said regular convex curve is essentially an arc.   4. Variable focal length lens according to claim 3, characterized in that the radius of said arc is between approximately 0.51 cm and about 5.1 cm.   5. Variable focal length lens according to claim 1, charac-   terized in that a central region of said membrane support member is transparent and has essentially the same refractive index as said transparent liquid.   6. Variable focal length lens according to claim 1, characterized in that said membrane support element (16) and said rigid lens (12) are hingedly connected and that said means (20) producing a variable spacing act to modify the space between said membrane support member and   said rigid lens, at points distant from said hinge.   7. Lens with variable focal length according to claim 6, charac-   terized in that said surface of toroidal shape has a shape in   cross section which is a regular convex curve.   8. Variable focal length lens according to claim 7, charac-   terized in that said regular convex curve is essentially an arc of circle.   9. Variable focal length lens according to claim 8, charac-   terized in that the radius of said arc is between approximately 0.51 cm and about 5.1 cm.   10. Lens with variable focal length characterized in that it comprises: - a rigid lens (12) - a membrane support element (16), arranged across and inside the field of vision of said rigid lens in being spaced therefrom, said membrane support member comprising a membrane support surface; - means (20) providing variable spacing for adjusting the spacing between said membrane support member and said rigid lens between a first spacing and a second spacing; - a transparent extensible membrane (15) arranged across the field of vision of said rigid lens and having a first surface in contact with said membrane support surface, and a second surface released from said membrane support surface, the periphery of said second surface being tangent to said surface supporting the membrane, and this for all the spacings between said first spacing and said second spacing; - a transparent liquid (21) filling the space between said rigid lens and said membrane; - flexible sealing means (23) serving to retain said liquid   transparent between said rigid lens and said membrane.   11. Variable focal length lens according to claim 10, characterized in that said support surface of the membrane is toroidal and has a cross-sectional shape which is a curve regular convex.   12. Variable focal length lens according to claim 11, characterized in that said regular convex curve is essentially an arc.   13. Lens with variable focal distance according to claim 12, characterized in that the radius of said arc is between approximately 0.51 cm and about 5.1 cm.   14. Variable focal length lens according to claim 10, characterized in that a central region of said membrane support member has substantially the same refractive index as said transparent liquid.   15. Variable focal length lens according to claim 10, characterized in that said membrane support element (16) and said rigid lens (12) are hingedly connected and that said means (20) producing a variable spacing act so as to modify the space between said support element of the   membrane and said rigid lens, at points distant from said hinge.   16. Variable focal length lens according to claim 15, characterized in that said membrane support surface (16 ') has a toroidal shape and has a cross-sectional shape which is a regular convex curve.   17. Variable focal length lens according to claim 16, characterized in that said regular convex curve is essentially an arc.   18. Variable focal length lens according to claim 17, characterized in that the radius of said arc is between approximately 0.51 cm and about 5.1 cm.   19. Lens with variable focal distance, characterized in that it comprises: - a rigid lens (12) - a membrane support element (16), arranged across and inside the field of vision of said rigid lens and being spaced therefrom, said membrane support member comprising a radially curved surface (16 '), which includes support means for supporting a transparent expandable membrane; - a transparent extensible membrane (15) arranged across the field of vision of said rigid lens and placed against said radially curved surface, said transparent extensible membrane being in contact with said radially curved surface, for all the spacings existing between said support element membrane (16) and said rigid lens (12); - a transparent liquid (21) filling the space between said rigid lens and said membrane; - flexible sealing means (23) serving to retain said transparent liquid between said rigid lens and said membrane; and - means (20) producing variable spacing to adjust the spacing between said membrane support member and said rigid lens.   20. Variable focal length lens according to claim 19, characterized in that said radially curved surface (16 ') has a   radial shape which is a regular convex curve.   21. Variable focal length lens according to claim 20, characterized in that said regular convex curve is essentially an arc.   22. Variable focal length lens according to claim 21, characterized in that the radius of said arc is between approximately 0.51 cm and about 5.1 cm.   23. Variable focal length lens according to claim 19, characterized in that said membrane support element (16) and said rigid lens (12) are hingedly connected and that said means ( 20) producing a variable spacing act so as to modify the space between said membrane support element and said rigid lens, at points distant from said hinge.   24. Variable focal length lens according to claim 23, characterized in that said toroidal surface (16 ') has a   radial shape which is a regular convex curve.   25. Variable focal length lens according to claim 24, characterized in that said regular convex curve is essentially an arc.   26. Variable focal length lens according to claim 25, characterized in that the radius of said arc is included   between approximately 0.51 cm and approximately 5.1 cm.