JPS6056493B2 - artificial implant lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an implantable lens made of a transparent material as a light refracting alternative to the crystalline lens surgically removed from the human eye.

A characteristic feature of cataracts is the clouding of the human lens.

The resulting loss of visual acuity can be avoided by surgically removing the crystalline lens and then implanting a suitable optical element. The most commonly used substitutes are the well-known cataract glasses, and contact lenses, which are placed directly on the cornea of the eye, are also used only when appropriate. The best functional substitute is an artificial crystalline lens surgically inserted into the eye. Such an artificial crystalline lens was researched by the Englishman Ridley, who began implanting organic glass lenses into the posterior chamber of the eyeball in 1940.

The expectations and hopes placed on this method were not met, as will be explained later, and this is the reason why this method was abandoned for some time until now. Quite often, the lens was displaced from the posterior chamber into the vitreous body behind it. Such a misplaced lens acts as a foreign body in the eye, is biologically unacceptable, and poses a significant long-term risk to the eye.
Another possibility as a light-refracting substitute for the crystalline lens removed from the eye was to implant a plastic lens into the anterior chamber of the eye.

These lenses, called anterior chamber lenses, are not placed in the natural lens position, ie, behind the iris, but are placed away from or near the iris in the region of the anterior chamber. Various models of such lenses have been devised and used. For example, those proposed by Strampelly, Sieleck, Walther, and Dunheim were used. However, over time it has become clear that these lenses are not physiologically acceptable to the eye. In addition, transparent plastic lenses (Pink Host, Wolst, etc.) began to become known, and these lenses consist of biconvex or plano-convex discs and are supported in a predetermined position, either in the anterior chamber of the eye or in the pupillary plane. It has various types of supports.

These lenses are made from polymethacrylate and usually have multiple loops of wire or plastic attached to their backside. The surface of this loop is located behind the back surface of the artificial lens. The loops are inserted through the pupil of the iris and placed against the back of the iris to hold the lens in place within the eye. After the lens is surgically inserted, the pupil is artificially (medicinally) constricted. This brings the back surface of the artificial lens into contact with the front surface of the iris, while the support loop rests against the back surface of the iris to ensure mechanical support of the artificial lens. These lenses are known as one-clip lenses because of their unique fixation method. This lens can be sutured to the iris by appropriately modifying the shape of the loop. Although the results reported to date for these zero iris lenses are favorable, there are critical points that remain important and essential to any of these lenses.

In other words, since the specific gravity of these lenses is greater than the specific gravity of the aqueous body of the eye, each time you move your eye, these lenses cause vertical movement, which creates undesirable mechanical pressure and strain on the delicate iris tissue that supports them. will be produced. In addition to polymethacrylate, polyamide has also been used as a material for such lenses.

However, a drawback of all these materials is that, in particular, lenses made from these materials cannot be sterilized in a completely surgical manner. Modern surgical techniques use thermal disinfection with hot steam or hot air to achieve complete sterility, including the eradication of bacterial spores. In the former of these two disinfection methods, the temperature is 134℃, the vapor pressure is 2.5atu=
3.5 atm) is allowed to act on the material to be disinfected in an autoclave for about 15 minutes. In the latter case, hot air disinfection, the substance to be disinfected is exposed to an artificially circulated air stream at 200° C. for about 30 minutes. Lens materials used heretofore cannot withstand such conditions. Another disinfection possibility, gas disinfection with ethylene oxide at a relatively low temperature of about 55° C., is too reckless for implanted lenses. This is because, as is generally known, this highly active gas accumulates in certain substances, and plastics belong to or contain such substances. Disinfection with high-energy radiation (cathode rays, beta rays, X-rays, gamma rays) must also be avoided in the case of such lenses, since this causes changes in the molecular structure of the plastic itself.

Substances resulting from changes in molecular structure resulting from high-energy irradiation are often toxic. In radiation-disinfected acrylate lenses (PMMA), erosion tends to increase considerably over time, resulting in clouding of the lenses. As a result, the only surgical method available was to disinfect the implanted lens using a chemical disinfection method.

That is, immediately after these lenses are manufactured, they are effectively sterilized and then stored in a fluid somewhat suitable for sterilization in vials. These vials are removed immediately before these lens surgeries. Chemical disinfectants are currently at least limited in their inability to kill bacterial spores, and these disinfectants can easily accumulate on plastic bodies and naturally leave the plastic body exponentially over time. I will do it. This phenomenon cannot be ignored, especially for eye transplants. Yet another drawback of the materials used in known lenses is that there is no certainty that the polymerization products are physiologically harmless.

Residues (residual monomers, oligomers, catalyst residues, hardener residues) remain on the lens material as a result of incomplete polymerization and can diffuse into the eye over time, damaging tissues and
As is already known, this may not necessarily result in internal irritation of the eyes. While it is true that many implanted lenses have been made and used with questionable materials, there is no reliable evidence that these materials are safe beyond all doubt. Furthermore, in conventional artificial implant lenses, the lens body and the support for holding it in a predetermined position within the eyeball are constructed separately, making manufacturing difficult and requiring troublesome assembly work.

The purpose of the present invention is to provide a substitute for lenses surgically removed from the human eye, to eliminate the drawbacks of the conventional artificial lenses mentioned above, and to mechanically strengthen ocular tissues compared to the rigid lenses used up to now. It is soft and flexible to an appropriate degree so as not to damage the skin, can be sterilized by a particularly safe medical method, namely heat disinfection, has a specific gravity approximately equal to that of the watery body of the eye, and is easy to manufacture. The aim is to provide an artificially implanted lens.

The present invention provides a lens body that has a lens function similar to that of the crystalline lens of an eyeball, and a lens body that can be held at a predetermined position within the eyeball so that the optical axis of the lens body substantially coincides with the optical axis of the eyeball. a radially extending support, which is homogeneous, flexible, crystal clear, has a specific gravity approximately equal to or slightly greater than that of the aqueous body of the eye, and has a specific gravity approximately equal to or slightly greater than that of the aqueous body of the eye; It is characterized by being formed from an integral molded body of silicone rubber that can withstand heat disinfection temperatures of °C.

After considering the conditions to be met among a large number of potentially usable plastics and carrying out countless appropriate tests and analyses, it was determined that silicone rubber satisfies all the above-mentioned requirements and is extremely suitable and physiologically ideal. It turned out to be the material.

In this context, awareness of the significance of the specific gravity of the materials used for the manufacture of implanted lenses plays a decisive role. This awareness is based in particular on knowing the shortcomings of conventional artificial lenses and their associated potential for damage. Due to the high specific gravity of the materials commonly used in conventional lenses, the lens can mechanically damage the iris to which it is attached, and is easily detached from the iris, a serious and previously unknown problem. This is a drawback.

On the other hand, when a lens made of silicone rubber having the specific gravity specified in the present invention is placed in the aqueous body, the acceleration force it receives during any movement or rocking movement of the eyeball is quite small, and as a result, This has the decisive advantage that the forces exerted on the iris are correspondingly smaller. On the other hand, even if the artificial implanted lens is made of a material with a specific gravity less than that of the aqueous body, the effects on the patient's operated eye will be considerably greater than would be expected. This difference in specific gravity between the lens material and the aqueous body can cause post-surgical damage to eyes fitted with conventionally constructed shift lenses, and this damage has hitherto been unpredictable and extreme. It was disliked by many people and often required additional surgery. The artificial transition value lens of the present invention can be placed in the posterior chamber, anterior chamber, or iris of the eyeball in the same manner as the above-mentioned conventional artificial transition value lens by means of a support formed integrally with the lens body.

An example of the artificial transition lens of the present invention preferably includes a conical lens body having the effect of refracting light at the center, and the front and rear ends of the lens body surround the lens body and are flexible. It is an annular disk, and between the two disks an annular space is formed that widens toward the outer end, and the inner edge of the iris surrounding the pupil is inserted into this space. In order to avoid mechanically damaging or irritating the very sensitive iris tissue, the end of the annular disc facing the annular gap of the lens is preferably rounded. In another embodiment of the invention, near the outer ends of the opposing surfaces of the annular disk, there is provided a circular or oblong button shape projecting beyond these opposing surfaces into the annular gap. Alternatively, protrusions or annular protrusions of a similar shape may be provided so that the iris is located in the gap between these protrusions, facing each other, and therefore on the outer periphery of the lens. These protrusions enable the lens to be supported against the iris by the ridges.

Therefore, the distance between these protrusions or annular protrusions is
The lens is preferably held in the correct position in the pupil plane by the iris in the anterior chamber of the eye, so that no other measures need to be taken. In the present invention, the inner edge portion of the surface of the annular disc of the lens defining the annular space is curved into a groove or rounded, and the pupil of the iris is directly connected to the curved surface of the lens. The seam between these surfaces should be a continuous smooth surface so that no unwanted edges or protuberances appear that could damage the pupil area.

In order to obtain an image by refracting light, only the optical path of the light passing through the lens body is important, so the size of the curved surface on the front surface of the lens should match the diameter of the central lens body, or the lens It is sufficient to match the diameter of the body or to make it slightly larger than the lens body, so that using this method the lens can be of minimum thickness and weight. Since the artificial transition value lens according to the present invention comprises the lens body and the support body as an integrally molded body of silicone rubber, manufacturing is extremely simple and the efficiency of mass production can be improved.

The present invention will be described in detail below with reference to the drawings.

FIGS. 1A and 1B are a plan view and a sectional view of an artificial transition lens according to the present invention. The lens body 11 is composed of a front surface 12 and a rear surface 13 which are convex curved surfaces, and a support body 14 extending in the radial direction of the lens body 11 is integrally formed on the outer periphery thereof.

The support body 14 has a shape obtained by cutting a part of an annular disk shown by a broken line, and an annular protrusion 15 that protrudes in a direction perpendicular to the lens body 11 is integrally formed on the outer circumference of the support body 14 . The surface of the protrusion 15 and the side circumference of the annular disk 14 are rounded to prevent mechanical damage to the iris tissue. This artificial transition lens is manufactured from a single piece of silicone rubber. The specific gravity of this silicone rubber is approximately equal to or only slightly greater than the specific gravity of the aqueous body inside the eyeball, so even when it is placed inside the eyeball, the lens does not move due to the action of gravity and is held stably. can. Furthermore, since this silicone rubber is transparent and homogeneous like crystal, its optical function is similar to that of a crystalline lens. Furthermore, because silicone rubber is flexible, its specific gravity is that of water. Coupled with the fact that the specific gravity is almost equal to that of the body, it does not damage tissues such as the iris of the eyeball. More importantly, the artificial transition lens of the present invention is made of silicone rubber that can withstand thermal sterilization temperatures of approximately 200°C, so it can be sterilized at high temperatures using water vapor, for example! It is safe because it can kill even bacterial spores. Also, since there is no need to rely on chemical disinfection, there is no fear that the disinfectant will gradually diffuse into the eye. When the artificial transfer lens of this example is transferred to the anterior chamber of the eyeball, the support 14 may be held between the cornea and the iris, and when transferred to the posterior chamber, the support 14 14 may be held between the cornea and the zonules of the crystalline lens. FIG. 2 is a sectional view showing an example of another artificial transition value lens according to the present invention.

There are two annular disks 16 and 1 on the outer periphery of the lens body 11.
7 is formed integrally with the lens body 11 from silicone rubber, and an annular space 18 is defined by the annular disks 16, 17 and the side periphery of the lens body 11. This annular space 18 is formed to receive the outer edge of the iris that constitutes the pupil when the lens is transferred into the eyeball, and is formed to become wider toward the outer edge.
Furthermore, the outer peripheries of the annular disks 16 and 1 are rounded to prevent mechanical damage to the surrounding tissues (when attached to the eyeball). At the edges of the opposing inner surfaces of the annular disks 16 and 17, annular protrusions 19 and 20 projecting into the annular disk 18 are formed integrally with the respective annular disks. By forming the annular protrusions 19 and 20, the edge of the iris constituting the pupil received in the annular space 18 after value transition can be held safely and reliably. Note that the annular discs 16 and 17 and the iris are not joined by adhesive, and the iris is surrounded by the aqueous body in the eye chamber up to the inner circumference of the iris that constitutes the pupil, so the width of the annular discs 16 and 17 is must be set to a width that can properly accommodate the iris. FIG. 3 is a sectional view showing the construction of yet another artificial transition lens according to the present invention.

The lens body 11 and the support body made up of annular discs 16 and 17 are constructed from an integral molded body of silicone rubber. A plurality of circular or oval button-shaped projections 2 are provided on inner surfaces 21 and 22 of the annular discs 16 and 17 facing each other.
3 and 24 are integrally formed on each annular disk. If such a plurality of protrusions 23 and 24 are formed, the annular space 18 will be closed in the same way as in the case of forming the annular protrusions described above.
This makes it possible to securely hold the iris received within. As explained above, according to the present invention, since the lens body and its support body are formed of an integral molded body of silicone rubber, mass production can be easily carried out by injection molding, etc. Since it is made of transparent silicone rubber, which has a specific gravity almost the same as that of the aqueous body, it eliminates the problem of the shifted lens moving within the eyeball due to the action of gravity after the shift, and it is also easy to support. rubber is 2
Since it can withstand high temperatures of 00°C or higher, high-temperature sterilization is also possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B are a plan view and a sectional view showing the structure of an example of an artificial transition lens according to the present invention;
FIG. 2 is a sectional view showing another artificial transition lens according to the present invention cut in half along the axis of symmetry, and FIG. 3 is a cross-sectional view showing still another artificial transition lens according to the present invention cut in half along the axis of symmetry. A cross-sectional view is shown.

11... Luns body, 12... Front, 13...
・Rear surface, 14...Support body, 16, 17...
Annular disk, 15, 19, 20... protruding, 18.
...Annular space, 23, 24...Protrusion.

Claims (1)

[Claims] 1. A lens body that has a lens function similar to that of the crystalline lens of the eyeball, and a diameter of the lens body that allows the lens body to be held in a predetermined position within the eyeball so that its optical axis approximately coincides with the optical axis of the eyeball. a homogeneous, flexible, crystal-transparent support having a specific gravity approximately equal to or slightly greater than that of the aqueous body of the eye, and a temperature of approximately 200°C. An artificial implanted lens characterized by being formed from an integrally molded silicone rubber body that can withstand heat disinfection temperatures.