CH616330A5 - Mounting collar for assembling an intraocular lens and its method of manufacture - Google Patents

Abstract

The collar is designed for precision mass production and convenient and reliable fitting. It comprises an annular body (12) intended to clamp a lens (10). It comprises two groups of feet (13, 14) arranged alternately. One of the groups of feet is intended to be on the internal side of the iris, and the other on the external side, so as to hold a collar/lens assembly. In order to facilitate the fitting operation, the feet of at least one group are flexible. The collar is manufactured from a blank obtained by erosion of a thin sheet covered with a photoengraving mask. A collar/lens assembly is intended to replace the lens of an eye which is clouded by cataracts. <IMAGE>

Description

The invention relates to a mounting ring for assembly to an intraocular lens and its manufacturing method. The lens is intended to be implanted to replace a lens clouded by cataracts or affected by another disease.

About 500,000 Americans have surgery each year to remove an opaque lens (cataract), causing vision loss. Modern therapy for cataracts is surgical removal; this is generally done either by gently removing the lens from the eye all at once, or by fragmenting the lens and removing the fragments by washing. When the lens with cataracts is removed, an alternate method should be used to focus the light entering the eye, so that a sharp image is focused on the retina. Strong spectacle lenses and contact lenses are also commonly used for this purpose, but both have significant shortcomings. Strong spectacle lenses magnify the image immeasurably, shorten distances, limit peripheral vision, and prevent both eyes from being used simultaneously if both eyes have not been cataract operated; contact lenses overcome some of these problems, but introduce others, driven by placement, removal and frequent maintenance.

The idea of implanting an intraocular lens in place of the lens that has been removed is not new, although it is of relatively recent origin. However, to date, a significant reason for the limitation of such a process has been the relative lack of implant lenses, since their production is based on small artisan workshops, and the quality of the lenses has been nothing less than satisfactory.

The invention aims to provide a mounting ring for assembly to an intraocular lens facilitating the application of implant methods of the indicated type, and making it easier and more reliable to set up operations.

The ring according to the invention is defined in claim 1.

The invention also aims to provide a method of manufacturing the ring allowing high quality to be obtained and suitable for mass production. The characteristics of the invention will appear to a person skilled in the art on reading the following description, together with the appended drawings which represent, by way of example, the preferred forms of the invention:

- fig. 1 is an enlarged perspective view, showing an intraocular lens and the unitary frame of the invention, ready for an implantation operation, as during a cataract operation;

- figs. 2 and 3 are plan views of the unitary mount of FIG. 1, fig. 2 to represent a state of intermediate formation and FIG. 3 showing the fully formed frame ready for assembly with the lens;

- figs. 4, 5 and 6 are fragmentary section views taken along the planes 4, 5 and 6 indicated in figs. 1 and 3;

- fig. 7 is a view identical to FIG. 3 to represent a modification;

- fig. 8 is an enlarged fragmentary view of the structure of FIG. 7, to allow the identification of dimensional characteristics;

- fig. 9 is a fragmentary sectional view, with contours in solid line taken along plane 9, and with dotted lines taken along plane 9 ′ of FIG. 7;

- fig. 10 is a view identical to FIG. 9 to represent a modification;

- figs. 11 and 12 are perspective views to represent additional modifications;

- figs. 13 and 14 are plan and perspective views to represent the blank shape and the finally arched configuration of a frame particularly suitable for manufacturing starting from a plastic material;

- fig. 14A is a fragmentary view identical to FIG. 14 to represent a variant;

- fig. 15 is a fragmentary plan view of a number of blank shapes of photographically reproduced lens mounts arranged in parallel series side by side so that they can be separated;

- figs. 16 and 17 are plan and fragmentary plan views identical to FIGS. 14 and 15, to illustrate another application of the method of the invention.

With reference to fig. 1 to 6, the invention represents an application of an implant lens 10 made of non-toxic transparent plastic, such as methyl methacrylate. The lens 10 has a refractive index and a size such that when it is adapted on the iris and immersed in the intraocular fluid, the eye thus implanted gives a very sharp focus of the image on the retina . The typical lens 10 is circular around its optical axis, although this is not an obligation; it can, for example, have a diameter of 5 mm and a peripheral edge thickness T of 1 mm or less.

In the example described, the unitary mounting structure 11 is fixed to the lens 10 and provides a first and a second group of feet extending radially outward for a positioning axially stabilized relative to the iris, the feet of one group being axially offset from those of the other group and angularly alternated with them, so that both sides of the iris contribute to stability. As shown, a circumferentially continuous ring 12 adapts to the peripheral contour of the edge of the lens 10, its positioning being adjacent to one of the faces of the lens. The first group of feet comprises three rods 13 angularly spaced, extending radially outward for fixing in the vicinity of the external side (anterior face) of the iris, the pupillary border of the iris closing on the circular edge of The lens. The second group of feet comprises three loops 14 extending radially outward in a radial plane offset axially relative to the ring 12, substantially at distance T. Thus, each of the feet of the second group comprises two short offset legs and spaced 15 in contact with the circular edge of the lens 10, and the radial part of the loop extends from the legs 15. In the

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case of the plastic lens 10 of FIG. 1, six L-shaped fixing claws 16-17 extend first radially inwards, then axially rearwards, these same claws being embedded in the adjacent edge of the lens 10.

The described mounting structure forming an adapter or lens holder ring 11 can be constituted by a simple piece of metal, of which all the fixing claws 16-17 and the stabilizing feet 13-14 are made in one piece with the ring 12. The metal must not react to tissues and body fluids and is therefore stainless steel, with a thickness of about 0.1 mm. We have found it convenient to make the blank or blank of FIG. 2 for the mounting structure 11, using photography and engraving techniques.

More specifically, with regard to the case of the blank of FIG. 2, originally, a drawing was prepared, on a very enlarged scale, that is to say magnified 40 times. This design was reduced by the photographic process to the final dimension, and multiplied in indexed locations to produce a photographic negative with a number of reduced images of the design. Then one of the kinds of metals tolerated by the body (i.e. stainless steel, platinum, irridium, etc.) was coated with a photosensitive substance. The negative was brought into contact with the photosensitive layer, exposed to light, and then developed by photographic inversion, thus erasing from the exposed surface the parts having been exposed to light. The remaining sheet was then placed in a chemical solution (iron perchloride) which corrosion removed the unnecessary substance, leaving only a completed outline of the blank. The corrosion process described has the advantage of having a tendency to give round, deburred edges, and it makes it possible to use lighter and thinner materials than anything which, to the knowledge of the applicant, has been able to be used. this day.

Fig. 2 shows the blank thus prepared, noting that the lobes 14 ′ extend in radial projection, so as to take account of the offsets 15 and the loops 14; in the same way, the barbs 16'-17 'extend radially outwardly, so as to take account of the legs, extending both radially inward and axially inward, claws 16-17. Folding dies are used to act on the blank of FIG. 12, so that all the necessary axial shifts are made, causing the reduction of the overall circle delimited by the lugs 14 and the expansion of the circle delimited by the claws 16-17, all as it appears by comparison plan views before and after figs. 2 and 3.

To complete the description of a real embodiment of FIGS. 1 to 6, it is indicated that each of the rod-shaped retaining feet 13 ends in a small head, to avoid presenting any sharp edge which would irritate the tissue of the iris. These heads are placed on a circle of 7.5 mm in diameter, and the external limits of the legs 14 are on a circle of 8 mm in diameter. The claws 16-17 are bent axially at a location offset radially inwards by about 0.15 mm relative to the ring 12; they are embedded in the lens 10 over a distance of about 0.30 mm in the axial direction. Such embedding can be carried out without drilling, by ultrasonic motor pulses directed axially applied to the claws 16-17, while maintaining the ring 12 and the feet 13-14 of the ring 11 in the damping state. The optical distortion of the lens 10 due to such a motor assembly of the ring with the lens is negligible.

In the embodiment of FIGS. 7 to 9, the outline of the frame blank is generally as described for FIG. 2, except that the radius Ri of the ring 12 'is greater than the radius R2 of the lens 10' around its optical axis by an amount AR which is slightly less than the effective amount AR 'representative of the radial projection towards l 'inside the fixing barbs 16'-17'. The groups of alternating stabilizing feet extending radially outward 13'-14 'are axially offset from each other, each group being offset in the direction opposite to

that of the other group, as can be seen in fig. 9. To adjust the ring in fig. 7 on its lens 10 ', the ring 12' is temporarily deformed by appropriate manipulation, to give it an approximate polygonal shape; the action of such manipulation is indicated by the arrows extending radially inward and radially outward, which symbolize the local application of a force to temporarily move radially outward , all the barbels 16'-17 'in order to release the outer edge of the edge of radius R2 of the lens 10'. Once centered axially around this border, the manipulation is interrupted to allow a return to the original shape by elasticity, the barbs 16'-17 'come into contact with the edge of the lens, and are placed in short radial housings, for example using an ultrasonic tool. The assembly is then completed and ready for sterilization and implantation.

Fig. 10 illustrates a slight modification of FIGS. 7 to 9, in which the ring 12 "is at an axial end of the lens 10" and the groups of stabilizing feet 13 "-14" determine the attachment to the iris in a plane axially offset from the lens 10 ". The barbs 16" -17 "are longer than those described above, in order to allow an axial offset from the ring 12" before bending radially inwards to come into contact with the edge of the 10 "lens and fit locally and radially in spaced locations.

In the embodiment of FIG. 11, the edge of the lens 20 has a peripheral groove 21, and the unitary mounting ring 22 is formed so as to be permanently adjusted in the groove 21 by the effect of elasticity. The ring 22 can also be formed from a blank in a single piece according to the photochemical technique indicated, and it can also be a circumferentially continuous structure. As shown, the loop-shaped legs 23 comprising a group of locating feet are connected integrally to the adjacent ends of the spaced arcs 24 of the ring, and the rod-shaped feet 25 of the other group extend radially from the respective arcs 24; the axial offset of these groups is incorporated in the legs 23, in the manner as described at 15 in FIG. 1, except for a small initial offset extending radially outward in these legs 23 at the point of junction with the arcs 24. Not subjected to stress, the arcs 24 have a curvature which matches that of the groove 21 and are preferably slightly and radially displaced inwards relative to the circle of the groove 21. To be adjusted to the lens 20, the arcs 24 are stretched outwards against the elastic action of the loops 23, so as to allow the establishment and fixing, by elasticity effect, of the arcs 24 in the groove 21. The assembly is then ready for sterilization and implantation.

In the embodiment of FIG. 12, the circular ring 30 of a unitary ring 31 is held in its assembly with a lens 32 by barbs 33-34 of a group 33, extending radially inwards which are engaged on an axial end lens 32 and barbs of another group 34, alternated with barbs of the first group, and engaged on the other axial end of lens 32, thus maintaining the assembly without the need for having use of mechanical embedding in the lens material.

As shown, the stabilizing feet relating to the iris of a group 35 are radial rods spaced at the locations on the ring of the barbs 34, and the barbs 34 include the axial offsets up to the thickness limit from the edge of the lens. The feet 36 of the other group include axial offsets at the points of junction with the ring 30, locations at which the barbs 33 also extend radially inwards. The feet 36 differ from the loops already described in that they are somewhat wound or looped in a common radial plane, the free end of the loop being provided with s

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of an opening 37. It will be understood that FIG. 12 represents the normal state and the normal orientation of the feet 36 in the absence of constraints.

According to a characteristic of the lens described, the flexibility by inherent elasticity of the feet 36 and their pierced ends 37 are used to facilitate the operation of insertion into the pupil of the iris. In preparation, a suture 38 such as a nylon filament is tied with a loop 38 'intermediate between its free ends 39-39'. The end 39 is threaded into all the foot openings 37 before passing through the loop 38 'and is then stretched to pull radially inwards by elasticity all the ends of the feet 37 inside the peripheral limits of the lens 30, as shown by the dotted contours 36 'in FIG. 12. In the operation of inserting the retracted legs 36 beyond the pupil, the ends 39-39 'of the suture are retained behind, the end 39 being held tightly until it is released when the legs 36 are well behind the iris. When the end 39 is released, the other end 39 'is pulled, thereby first removing the loop 38' and allowing the remaining end 39 to exit the loop 38 'and all openings 37 before removal total suture.

Figs. 13 and 14 show another embodiment of the lens mount of the invention, in which the annular body comprises several parts spaced in an arc 40-41-42 between loops connected integrally 43, and in which each loop , a small bridge 44 (at a radial offset Ar with respect to the circle of arcs 40-41-42, in the blank of fig. 13) connects the legs spaced from the loop and reinforces the circumferential integrity of the body around the periphery . A lens retaining device 45 extends radially inwards from each bridge 44, effectively isolated from the associated bridge 44, except with regard to the connecting lugs in an arc of a circle integral and spaced 46. The feet rod-shaped 47 of the embodiments described above radiate centrally from each of the arcs 40-41-42.

The blank of fig. 13 is curved by appropriate manipulation, according to the lens retaining configuration shown in FIG. 14, in which it can be seen that the projections 45 have been axially offset from the plane of the arcs 40-41-42, so that the respective axial limits of the periphery of the lens element (suggested by the dotted outline) 48) are engaged to permanently fix the lens to its frame. It will be understood that the relatively appreciable radial distance A r 'by which the bridge 44 is connected to the legs of each loop 43, in the context of the relatively sensitive nature of the connection of each loop 43 to its adjacent arc (40-41 -42), allows momentary radial manipulation towards the outside of any projection 45 engaged with the lens simply by axially bending one of the loops 43, thus easily allowing the insertion and fixing of a lens 48 at its border.

To complete the description in fig. 14, it will be understood that the loops 43 have also been subjected to bending, such that each bridge 44 extends axially so as to give an axial offset for the radial plane of the loops 43 relative to the radial plane of the feet 47, so that that the loops 43 and the feet 47 can be engaged with the opposite sides of a support iris.

Figs. 13 and 14 also show that a singularly wide arc 42 has been provided for identification purposes, that is to say, manufacturer's mark, lens identification code and date of manufacture.

So far, the invention has been described in the particular context of the use of a metal as a material for the mounting structure of the lens. This should not be seen as prohibiting the use of other materials such as, for example, suitably inert plastic, such as nylon or polypropylene. In a preferred use of a thin sheet of Nylon or a high temperature polyimide (i.e. Kapton, a product of EI DuPont Company), the same etching technique can be used, as shown below - above for the case of an engraved metal sheet. This close resemblance will appear on reading Example 1, which is a detailed enumeration of the successive phases for the production of the plastic article.

Example 1:

1. A nylon sheet or a polyimide film, of a thickness of 0.05 to 0.12 mm, in the same thickness range as that used in the etched metal technique described above is chosen. The chosen plastic sheet is put to the test for the water content, the mechanical resistance and, by means of the spectrograph, for the fidelity of composition.

2. The sheet is washed in acetone and then air dried.

3. The sheet is washed in distilled water and then air dried.

4. Examine the sheet visually to verify cleanliness and detect surface defects.

5. The sheet is prepared for a photoresist layer under vacuum or for another deposit of chromium.

6. Apply a photoresist layer of photographic emulsion on both sides of the sheet and allow it to air dry.

7. By first preparing an enlarged drawing 20 to 50 times, then reducing it, by photography, in successive operations as necessary, ending with the reproduction on a photographic plate, we obtain a mother negative at the desired final scale ; the mother negative preferably includes a certain number of copies of the same drawing reduced by photography, arranged side by side with interconnected legs, as can be seen for the tangential connections in the form of rod 50 to the legs of the outline repeated in fig. 15.

8. The nylon or polyimide sheet or film is then placed in a frame where a vacuum is created to flatten it and hold it firmly against a glass plate, and the mother negative is exposed photographically on both sides of the sheet, in precise correspondence.

9. The exposed sheet is developed and as a result, the surfaces masked by the negative and which, therefore, were not exposed to light, are not developed. The operator washes the surfaces affected by light, and in the case of a polyimide sheet, there may be a first etching action attributable to the operator.

10. The developed sheet is fixed.

11. The sheet is chemically etched, hydrazine hydride being used for the etching of a nylon or polyimide sheet and which can be used for certain other plastics.

12. The photoresist layer is washed using either a plasma process or a fluorocarbon cleaner.

13. The resulting lens frame sheet, composed of several connected white parts, is then immersed in a 30% hydrazine hydride solution, in order to round the edges of the different parts.

14. The sheet comprising the parts terminated elsewhere is released by increasing the temperature of the sheet up to 149 ° C. in the case of nylon, or 260 ° C. in the case of polyimide at high temperature.

15. The mounting rings are detached from the sheet at points 50, to create individual circular parts in white, as in fig. 13.

16. The individual circular parts are profiled by mechanical folding, as shown in fig. 14, and the profile is examined.

17. A lens of glass or molded plastic is chosen and mounted, as indicated by the dotted line in fig. 14.

18. The complete assembly is examined and marked with the serial number and the code, at 42 in fig. 14.

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19. We proceed to the final examination.

20. It is cleaned with plasma and the complete individual assembly is packaged, then it is sterilized with gas or in an autoclave.

21. The final examination is carried out through the packaging window, then the packaging is marked with the date and the batch number.

It is also possible to apply a totally different technique of photoengraving or other erosion process for the manufacture of lens frames of the type sought here, particularly as regards frames made from plastic sheets, as will be appreciated. when reading example 2.

Example 2:

1. Two similar metal covers or mother sheets, for example made of aluminum, are prepared according to the photogravure technique described above.

2. Choose a suitable plastic sheet, such as Nylon or polyimide film, 0.05 to 0.13 mm thick, and test it, washing it and drying it as indicated in points 1 to 4 of Example 1.

3. The metallic mother sheets are glued and plated on the front and back of the plastic sheet, in precise correspondence.

4. The plywood sheet, thus masked, is exposed to the discharge of a plasma generator or a micro-ionic rolling mill, in the presence of an appropriate reactive gas, for 1 h for example, up to that the desired contour was created by the erosion of the non-hidden parts of the plastic material.

5. The cement is dissolved to allow removal of the aluminum covers or mother sheets for cleaning and reuse.

6. The printed plastic sheet has the appearance of fig. 15 and it can be cleaned by an additional exposure as in point 4 of this example 2, for example by an exposure time of approximately 2 min, to remove any possible organic debris or burrs.

We will realize that we have described here intraocular lenses and mounting structures in accordance with all the objectives announced and, what is important, suitable for mass production techniques, maneuver and inherent precision. The drilling operations, previously considered to be necessary, have been completely avoided, as well as the implementation of multiple parts, thus simplifying the manufacture and avoiding the creation of lost particles. Although plastic lenses have been specially mentioned in several explanatory passages, it will be understood that the invention is not necessarily limited to such use. For example, glass lenses will be preferred and can certainly be fitted securely, using the structures of Figs. 11 to 14. Likewise, although the peripheral contours of the rings of circular lenses have been described for all the forms, it will be understood that it was purely for the purpose of simplifying the description, in that the techniques and structures described s 'also apply, whatever the peripheral contour of the lens; for example, an oval lens outline can be chosen for faster insertion beyond the pupil, for the needs of some patients, and to reduce the possibility of surgical trauma. Furthermore, the inherent nature of the mounted lenses which have been described is such that only an absolute minimum of structure protrudes into the anterior chamber of the eye; thus, the danger of contact of the corneal tissue with any part of the described intraocular lens structure is significantly less than with existing structures. For the described lens forms, in which the iris closes on a circular lens contour, there is only minimal stress on the sphincter muscle, with a reduced subsequent risk of trauma.

So far, it has been indicated that the lens element on which the described mounting ring fits can be made of glass or plastic, it being understood that the lens element is a separate article of manufacture, subsequently assembled to its mount. It will however be understood that each of the described mounting ring embodiments applies to the establishment in a suitable cavity formed by molding the lens, so that at least the part of the mounting ring holding the lens is embedded in a plastic lens element which is injection molded into the cavity. The blank of fig. 13 is particularly suitable for such use when molding the lens element by injection, in that it is not necessary that the extension 45 holding the lens is curved radially, as shown in FIG. 14, but that it is simply bent axially, as shown at 45 'in FIG. 14A, in which case the material of the injection molded lens can be forced into the molding process to enter the slot or opening 49 between the bridge 44 and the extension 45. Thus molded, the lens element will be positively wedged and put in place by the lens material formed radially outward at each of the openings 49.

It has also been indicated above that the preferred method of etching the developed portions of a photographic reduced lens mount master negative is suitable for the mass production of a number of such lens frames, arranged in adjacent parallel series , as suggested in fig. 15. And such production lends itself to other options with regard to assembly with plastic lens elements. In one method, the individual mounting blanks are separated at 50, then are bent to form protrusions holding the lens, as described at 45 'in connection with FIG. 14A; the individual frame, thus prepared, can then be assembled with the lens molding cavity for localized embedding in the lens material during injection molding of the lens. Alternatively, the protrusions 45 'holding the lens can be curved out of all lens mounting structures in large numbers on a single sheet, before separation at 50; in this case, the sheet of the lens frames thus formed being suitably introduced into a multi-cavity mold for the simultaneous molding of a seemingly spaced number of lenses, all the lens-frame assemblies can be made in a single phase of injection molding, that is, a single injection molding of all the lens elements, each assembled in its own frame. Thus formed, the assemblies are easily handled, shipped and stored as a single sheet, with the possibility of separating the individual assemblies in 50, only when and as necessary.

Although the invention has been described in detail for the preferred forms shown, it will be understood that modifications can be made without departing from the scope of the invention. For example, it will be understood that the reference to metal for the ring structures of Figs. 11 and 12 are given only by way of example, since plastics, suitably rigid and non-toxic shaped in a similar manner, can also serve the same purpose. Likewise, the reference to a photochemical preparation of the metal blanks is an example of a preferred technique, in that the photoresist layer techniques, used in printed circuit technology, with subsequent release of an undercoat, can also be used; and it will be understood that the use of positive and negative terminology in connection with the photographic process is an example and is not limiting, in that it must be understood that the techniques of development by inversion starting from an original positive, directly up to a positive developed image, are also applicable.

Also, although the structures of metal rings have been described in conjunction with the lens element thus mounted, it will be understood that such unitary structures can be and, in certain cases, are preferably subjected to a protective coating.

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inert material of plastic such as nylon, thus ensuring against any possibility of smudging or tiny protruding metal barb coming into contact with the tissue of the eye. Likewise, it will be understood that the embodiments of the plastic sheets and the methods described relate to basic structural shapes and do not necessarily have to do with such a finish or such a final coating if these are necessary for specific purposes; for example, a coating of inert material, such as Teflon or platinum, deposited under vacuum or by vaporization, can be applied to a ring finished elsewhere, in order to increase the guarantee of non-toxicity of the final product.

Furthermore, it will be understood that, although all the mounting rings described so far have been of a unitary unitary construction, the manufacturing methods described can also be used.

apply to mounting rings with multiple parts, such as the two-piece configurations described in detail in US patent application No. 780445 of May 28, 1976 in the name of the present applicant. The basic blank, that is to say for that serving for half of such a structure, is shown in solid lines at 60, 20 in FIG. 16, with its two mounting lobes 61 projecting radially outward from its annular body 62, at diametrically opposite locations; another similar element 63 is shown in dotted lines with its two mounting lobes 64, in an angular alternating arrangement with respect to the lobes 61. The lobes 61 of a ring element 60, and the lobes 64 of the other ring element 63 are held in mortise interlobe locations 65-65 'of the respective elements 60-63, and the ring elements thus assembled set up and hold only one lens 66; when inserted into the eye, the lobes 61 stabilize the assembly with respect to one side of the iris, and the lobes 64 give stability with respect to the other side of the iris. The nature of the material of the elements 60-63 should be such that at least the lobes to be inserted beyond the iris are flexible and elastic, and very satisfactory assemblies can be provided in which the two ring elements 60- 63 are copies of each other, made of suitable plastic such as nylon or a polyimide sheet, according to the methods described in Example 1 and in Example 2. Thus, a single sheet with multiple elements , a fragment of which is shown in fig. 17, can be prepared to meet the needs for elements of mounting rings 60-63 of a number of assemblies of FIG. 16. It will also be understood that chemical etching and mechanical, electronic or other erosion must be considered as equivalent phases of handling, depending on the approach to the manufacture and the materials chosen.

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Claims (35)

616,330 2 1. Mounting ring for assembly with an intraocular lens (10, 10 ′, 20) provided with a peripheral edge surrounding its optical axis at a distance therefrom, characterized by an annular body (12, 60, 63) continuous circumferentially and open in its center, conforming substantially to the periphery of the lens (10) and adapted to adjoin in correspondence the periphery of the lens (10,10 ', 20) and by at least one group of feet (31, 61 , 64) for positioning the lens, in one piece with said annular body (12) and extending radially outward from it, in angular spacing ratio, at least one of said feet being flexibly foldable to allow momentary elastic bending inwards to facilitate the insertion operation via an iris opening. 2. Ring according to claim 1, characterized in that all the feet (36) of said group are flexible. 3. Ring according to claim 1, characterized in that it constitutes the sole assembly, stabilized in the iris, of the lens, and in that it comprises two groups of feet, the feet of a group being in taken with one side of the iris and being in alternation and angular spacing relationship with the feet of the other group, the feet of said other group being designed to be engaged with the other side of the iris. 4. Ring according to claim 3, characterized in that each of said groups comprises three feet. 5. Ring according to claim 3, characterized in that the feet of one of said groups are offset axially relative to the feet of the other of said groups. 6. Ring according to claim 1, characterized in that the annular body is composed of two similar parts (60, 63) of elastic material, each part being intended to be engaged respectively with the axially opposite sides of the periphery of an element lens (66) interposed, and provided with lens positioning feet (61, 64) for securing said articles to each other to hold the lens element interposed. 7. Ring according to claim 1, characterized in that it comprises several fixing elements (16, 16 ', 17, 17', 33, 34) angularly spaced and extending inwards, in one piece with said annular body (12), intended to engage with the local peripheral portions spaced from the lens (10). 8. Ring according to claim 1, characterized in that it is of one-piece and metallic construction without welding. 9. Ring according to claim 1, characterized in that said ring is of one-piece construction and seamless plastic. 10. Ring according to claim 7, characterized in that said fastening elements are rod-shaped projections (16, 17) with axially directed ends, intended to be embedded in the adjacent peripheral parts of a plastic lens ( 10). 11. Ring according to claim 7, characterized in that said fastening elements are rod-shaped projections (16 ', 17') with radially directed ends, intended to be embedded in the adjacent peripheral parts of an element plastic lens (10 '). 12. Ring according to claim 3, characterized in that said annular body is of limited elasticity and comprises several parts in an arc of a circle (24) angularly spaced, interconnected solidly by elastic arcs (23) oriented radially outwards delimiting at least one of said groups of feet. 13. Ring according to claim 7, characterized in that said fastening elements are rod-shaped projections provided with radially directed ends (33, 34) some of which (33) are axially offset relative to the others (34) for a grip by axial retention with the opposite sides of the periphery of the lens. 14. A method of manufacturing a mounting ring according to claim 1, characterized by the preparation, on a very enlarged scale, of a plan drawing of a flat unitary blank shape for the ring, said drawing having a configuration delimiting an annular body with feet extending radially outward at angularly spaced locations, the selection of a thin sheet of material which can be eroded or corroded and which is tolerated by the human body, applying, on a face of said sheet, of a corrosion-resistant cover which is a photographic reduction of said mother view in plan up to the final scale desired for the ring, and the submission of the hidden face of said sheet to a corrosive atmosphere , whereby a finished blank is obtained, conforming to the configuration of the cache. 15. Method according to claim 14, characterized in that a second similar corrosion-resistant cover is applied to the other face of the sheet, in exact correspondence with the application of the first cover mentioned. 16. The method of claim 14, characterized in that the application of the cover causes the coating of the sheet with a photosensitive material, photographic printing and the development of said photographic reduction. 17. The method of claim 14, characterized in that the application of the cover comprises the selection of a sheet of corrosion-resistant material for the manufacture of the cover, the photogravure treatment of the sheet of material for the cover, in accordance to said photographic reduction, thus producing a separate cover from the sheet of material which can be corroded, and the fixing of the cover to one face of the sheet which can be corroded during exposure to the corrosive environment. 18. The method of claim 14, characterized in that the operation of submission to a corrosive atmosphere consists of chemical etching. 19. The method of claim 14, characterized in that the operation of submission to a corrosive atmosphere consists of exposure to the discharge of a plasma generator. 20. The method of claim 14, characterized in that the operation of submission to a corrosive atmosphere consists of exposure in a micro-ionic press in the presence of an appropriate reactive gas. 21. The method of claim 14, characterized in that said cache contains a number of adjacent copies of the photographic reduction of said drawing. 22. Method according to claim 14, characterized in that, to produce the cover, one side of the sheet is coated with a photosensitive material, the photographic printing of said photosensitive layer is carried out on a reduced scale compared to said mother view in plan, and the development of the exposed layer to obtain an image of the annular body on the sheet, and in that the developed side of the sheet is subjected to a corrosive chemical solution to obtain the finished annular blank. 23. The method of claim 22, characterized in that the coating operation is done on both sides of said sheet, and in that said photographic printing on a reduced scale is, moreover, done in inversion on the other side of said sheet with the two prints in exact geometric correspondence, the two sides of the impressed sheet being developed and then engraved. 24. The method of claim 23, characterized in that the two prints are made simultaneously on the opposite sides of the sheet. 25. The method of claim 22, characterized in that said photographic impression comprises a number of adjacent repeated prints, of the same mother view in plan reduced by photography, said prints being arranged side by side on the same photosensitive sheet, l at least one of said feet of the adjacent printed images being interconnected. 26. The method of claim 22, characterized by the preparation of the drawing on which the lens retaining projections extend radially inwardly at angularly spaced locations, and in that after obtaining a 5 10 15 20 25 30 35 40 45 50 55 60 65 3 616,330 blank completed, some of the feet extending radially outward are flexed for an axial offset relative to the other feet extending radially outward. 27. The method of claim 26, further characterized by bending at least one of the lens retaining projections outside the plane of said blank to give lens retaining elements axially offset from said plane. 28. The method of claim 26, characterized in that the material of the sheet is a polyimide. 29. Method according to claim 26, characterized in that the material of the sheet is chosen from the group comprising polyamides, polyimides and polypropylene. 30. The method of claim 26, characterized in that the corrosive chemical solution consists essentially of hydrazine hydride. 31. Use of the ring according to claim 1, as a mount in a ring-lens assembly. 32. Use according to claim 31, characterized in that the lens is held between two respective parts (60, 63) which make up the annular body. 33. Use according to claim 32, characterized in that the lens is made of worked optical glass. 34. Use according to claim 32, characterized in that the lens is made of optically worked transparent plastic. 35. Use according to claim 31, characterized in that the lens (20, fig. 10) is optically opened and has a continuous periphery around its optical axis.