JPH06245944A - Artificial cornea - Google Patents

Abstract

PURPOSE:To improve the adaptability of the artificial cornea to a living body by boring a sheet-like supporting member, which consists of a metallic material, such as titanium, is formed to a truncated dome shape and is provided with several pieces of notches on its outer edge and/or inner edge, with a central hole and fitting an optical member consisting of a photosensitive material into this central hole. CONSTITUTION:This artificial cornea 1 used for restoring the visual function of a corneal disease consists of the supporting member 2 and the optical member 3. The optical member 3 is fitted and fixed by press fitting the member into the central hole 2b from the front side or rear side of the supporting member 2. The supporting member 2 is formed of the metal, such as pure titanium, titanium alloy or tantalum, having no harms to the living body, has the truncated dome shape as a whole and is formed with respectively >=3 pieces of the notches 2b, 2c in the outer edge part 2e and inner edge part 2f of the main body 2a. The concd. stresses generated in the outer edge part 2e and the stresses concd. to the inner edge part f at the time of fitting the optical member 3 into the central part 2b are respectively absorbed by these notches 2b, 2c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial cornea that is used to restore visual function by replacing a cornea that has deteriorated or lost visual function due to corneal disease.

[0002]

2. Description of the Related Art An artificial cornea is generally fixed on the surface of a natural (human body) cornea or an optical member made of a light-transmissive material that is not harmful to the body, or inserted between the anterior and posterior layers of the cornea. As a result, there are a support member configured to support the optical member and integrally formed of the same material, and a combination of an optical member and a support member made of different materials.

The most common material used for such an artificial cornea is a synthetic resin material such as PMMA or silicon, and there is an artificial cornea in which an optical member and a supporting member are integrally formed using these materials. .

Synthetic resin materials such as PMMA and silicon used for artificial corneas are less harmful to humans. However, on the other hand, it does not fit well with the surrounding corneal tissue, and since a slight gap is created between the artificial cornea and the cornea, bacteria may enter the anterior chamber through it and cause ocular inflammation. Furthermore, there is a problem that the artificial cornea is discharged from the cornea due to inflammation in severe cases.

In addition, the optical member is formed of the above synthetic resin material, and in order to improve the compatibility with the living body, autologous bone of the patient is sampled and processed to form a supporting member. there were.

[0006] However, after such an artificial cornea is transplanted into the cornea, the support member and the cornea are intimately intimate with each other for a while, and a good condition continues, but thereafter, the support member itself is gradually put into the living body. There was a problem that it was absorbed and decomposed.

[0007] Further, there is an artificial cornea composed of an optical member made of single crystal alumina and a supporting member made of polycrystalline alumina using alumina ceramics as a material of the artificial cornea. Since it is made of polycrystalline alumina, it is thicker than the cornea having a thickness of 0.5 to 0.7 mm, and therefore, the optical member had to be suture-fixed to the sclera of the eyeball or the eyelid. For this reason, it has not been put to practical use at present because the surgical invasion was extremely large and many complications occurred in clinical trials.

Therefore, in order to solve the above-mentioned problem of the artificial cornea, the optical member is formed of a synthetic resin material such as PMMA or silicon and the supporting member is made of pure titanium like the artificial cornea proposed by Mr. Aladna Curkova. An artificial cornea composed of a metal material that is not harmful to the body, such as titanium alloy or tantalum, was used.

In such an artificial cornea, a cylindrical optical member A as shown in FIG. 7, a ring C having a central hole C ₁ for fitting the optical member A, and the ring C are provided. flap D which is integrally formed on the left and right, from or composed prosthesis 20 support member B consisting of D, as shown in FIG. 8, the central hole E ₁ of shield support members E, columnar optical There was an artificial cornea 30 in which the member A was fitted.

In these artificial corneas 20 and 30, the supporting members B and E are made of the above-mentioned metal materials, so that they are well compatible with the corneal tissue, and the thickness of the supporting members is extremely small, so that there is almost no surgical invasion. was there.

[0011]

However, in the above-mentioned artificial cornea in which the supporting member is made of a metal material that is not harmful to the living body,
The shape of the support member is flap-shaped or shield-shaped, and the difference in shape from the spherical cornea is large. Therefore, after transplanting into the cornea, after a while, a part of the support member breaks the cornea and is exposed to the outside, and bacteria invades the anterior chamber from that part, causing total ocular inflammation. There was a problem.

[0012]

In order to solve the above problems, according to the present invention, the supporting member is made of a metal material which is not harmful to human body, and the shape thereof is a truncated dome shape.

Further, when a thin plate-shaped metal material is formed into a truncated dome shape by a press molding machine and when an optical member is fitted into a central hole formed in the support member, an outer edge portion of the support member and / or Alternatively, since stress concentration is likely to occur at the inner edge portion, three or more notch portions are formed at the outer edge portion and / or the inner edge portion of the support member so that the partially concentrated stress is absorbed by these notch portions. I chose

[0014]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view of an artificial cornea 1 according to the present invention. The artificial cornea 1 is composed of a supporting member 2 and an optical member 3, and the above-mentioned optical member is provided in a central hole 2d from the front side or the rear side of the supporting member 2. The structure is such that the member 3 is press-fitted and fitted and fixed.

The support member 2 is made of a metal that is not harmful to human body, such as pure titanium, titanium alloy, or tantalum, and has a truncated dome shape as a whole and a main body 2a.
The outer edge portion 2e and the inner edge portion 2f each include three or more outer edge cutout portions 2b and three inner edge cutout portions 2c.

These outer edge cutouts 2b and inner edge cutouts 2c
When the support member 2 is formed into a truncated dome shape by a press molding machine, the concentrated stress generated in the outer edge portion 2e and the support member 2 when the optical member 3 is fitted into the central hole 2d of the support member 2 It has the effect of absorbing the stress concentrated in the inner edge portion 2f of each.

Next, the optical member 3 is made of single crystal alumina or a synthetic resin material such as PMMA or silicon, and the front surface 3a and the rear surface 3b are optically suitable as shown in the sectional view of FIG. Is formed into a dome-shaped disk having various curvatures, and a step portion 3d having a taper opening forward is formed along the circumference of the side surface 3c so as to be fitted into the central hole 2d of the support member 2. There is. As a means for fixing the support member 2 around the optical member 3, instead of the step 3d, a groove 3e may be formed along the circumference of the side surface 3c as shown in the sectional view of FIG.

In the artificial cornea 1 constructed as described above, as shown in FIG. 4, the main body 2a is inserted between the anterior layer F and the posterior layer N of the cornea K, and the central hole 2d is formed by the support member 2. First, since the supporting member 2 is made of a metal material that is not harmful to the living body, it has good compatibility with the corneal tissue, and further, the outer edge cutout portion 2b and the inner edge portion. The notch 2c absorbs the stress concentrated in a part of the support member 2, so that the support member 2 is not distorted or deformed. As a result, no gap is formed between the cornea K and the cornea K.

Further, since the supporting member 2 is formed into a truncated dome shape, it conforms to the shape of the cornea K, and a part of the main body 2a does not break the cornea K and is exposed to the outside. By using the above metal material for the support member 2, it can be made sufficiently thinner than the cornea K, and as a result, there is almost no surgical invasion.

As described above, since the artificial cornea 1 does not cause a gap between the cornea K and the cornea K and does not break the cornea K, bacteria enter the aqueous humor W in the anterior chamber S. do not do. Therefore, the artificial cornea 1 can be stably transplanted into the cornea K without bacteria causing allophthalmitis.

In addition, the outer edge cutouts 2b and the inner edge cutouts 2c also have a role of preventing dehydration in the anterior layer F caused by separation of the cornea K into the anterior layer F and the posterior layer N, and accompanying nutritional deficiency. Is playing.

Hereinafter, preferred embodiments of the artificial cornea 1 according to the present invention will be described. First, the curvature R of the support member 2
Is approximated to the curvature of the cornea K = 7 mm to 8 mm, and the curvature R =
It is preferably 6 mm to 9 mm.

The thickness of the supporting member 2 is 0.025 mm.
~ 0.4 mm is preferred. When the thickness is less than 0.025 mm, distortion and deformation are likely to occur, and when the thickness is more than 0.4 mm, the amount of the remaining cornea K must be reduced, so that the force of the cornea K to hold the artificial cornea 1 is reduced. It becomes too small and the artificial cornea 1 moves frequently. From the above, there is a possibility that a space will be formed between the cornea K and bacteria from there, and the bacteria will invade the anterior chamber S to cause ophthalmitis.

Next, the outer edge cutout 2b has an outer edge width A of 0.15, which is the distance between two points where the outer edge 2g begins to enter the same outer edge cutout 2b shown in FIG.
mm to 2.55 mm, and the suitable number is 3 to 20 mm.
When the outer edge width A of the outer edge notch 2b is 0.15 mm or less, or the number is less than 3, the supporting member 2
The outer edge portion 2 of the support member 2 when forming a truncated dome shape
e is distorted, deformed, or cracked. On the other hand, when the outer edge width A is 2.5 mm or the number exceeds 20,
The support member 2 cannot be formed into a truncated dome shape with a constant curvature R, and the outer edge portion 2e opens forward as shown by the cross-sectional shape in FIG.

Therefore, a large pressure is locally applied to the anterior layer F of the cornea K, which may cause inflammation or the like at that site.

The inner edge notch 2c has an inner edge width B of 0.15, which is the distance between two points where the inner edge 2h shown in FIG. 5 begins to enter the same inner edge notch 2c.
mm to 1.55 mm, and the suitable number is 3 to 20 or less. When the inner edge width B of the inner edge notch 2c is 0.1 mm or less or the number is less than 3, when the optical member 3 is fitted into the central hole 2d of the support member 2, distortion, deformation, etc. may occur. Occur. On the other hand, when the inner edge width B is 1.5 mm or the number exceeds 20, the inner edge portion 2f becomes the optical member 3.
Since the force for supporting the inner edge portion 2f becomes too small, the inner edge portion 2f is distorted or deformed due to the movement of the eyelid or the like. As a result, a space is created between the cornea K and the bacteria, from which the anterior chamber S
May enter into and cause ophthalmitis.

In the artificial cornea 1 according to the present invention, the outer edge portion 2e can be formed without forming the outer edge cutout 2b in the support member 2.
Is not distorted or deformed, or if the inner edge portion 2f is not distorted or deformed without forming the inner edge cutout 2c, in addition to those shown in the drawings, Outer edge notch 2b or inner edge notch 2c
Only one of these may be formed on the support member 2.

A coating layer made of a biocompatible material such as hydroxyapatite or collagen is provided on the surface of the main body 2a of the support member 2 or is discolored by anodic oxidation or the like to adapt to the color of each individual's brilliance. The colors may be colored.

[Experiment 1] A disk-shaped pure titanium plate having a thickness of 0.3 mm was molded by a press molding machine into a truncated dome shape having a curvature R = 8 mm, and as shown in Table 1, the outer edge cutout 2b was formed. After producing 51 kinds of support members 2 having different outer edge widths A and the number thereof, the surface shape was measured by a three-dimensional laser measuring instrument.

Next, according to the evaluation criteria, the sample with an error of 50 μm or less from the design dimension is passed, and the others are rejected.
The measurement results were evaluated. The results are shown in Table 1.

[0031]

[Table 1]

As is apparent from Table 1, the outer edge width A of the outer edge notch 2b of the support member 2 is 0.15 to 2.55 mm.
Also, it was found that the number is preferably 3 to 20.

[Experiment 2] A disk-shaped pure titanium plate having a thickness of 0.3 mm was molded by a press molding machine into a truncated dome shape having a curvature R = 8 mm, and as shown in Table 2, the inner edge cutout 2c was formed. After producing 47 types of support members 2 having different inner edge widths B and the number thereof, the optical member 3 was fitted to the support members 2 to produce the artificial cornea 1 according to this example.

Next, regarding these artificial corneas 1, whether the support member 2 and the optical member 3 are loose, and whether the inner edge portion f is distorted or deformed by applying a pressure of 20 g from the front side. I confirmed whether or not the immobility was secured. The results are shown in Table 2.

[0035]

[Table 2]

As is clear from Table 2, the inner edge width B of the inner edge notch 2c of the support member 2 is 0.15 to 1.55 mm.
Also, it was found that the number is preferably 3 to 20.

[Experiment 3] A disk-shaped pure titanium plate having a thickness of 0.3 mm was press-formed into a truncated dome shape having a curvature R = 8 mm, and as shown in Table 3, the outer edge width of the outer edge notch 2b was obtained. A and the number thereof, and the inner edge width B of the inner edge notch 2c
Further, 52 types of support members 2 having different numbers and different numbers were produced, and then the optical member 3 was fitted to the support members 2 to form the artificial cornea 1 according to the present example.

Next, the surface shape of these artificial corneas 1 was measured with a three-dimensional laser measuring instrument. The measurement results were evaluated according to the evaluation criteria that the sample with an error of 50 μm or less from the design dimension was acceptable, and the others were rejected. The results are shown in Table 3.

[0039]

[Table 3]

As is clear from Table 3, the outer edge width A of the outer edge notch 2b of the support member 2 is 0.15 to 2.5 mm,
The inner edge width B of the inner edge notch 2c is 0.15 to 1.5 m.
It has been found that the m and the number are preferably 3 to 20, respectively.

[Animal Experiment 1] In the artificial cornea 1 as shown in FIG. 1, the thickness of the support member 2 made of tantalum is shown in Table 4.
And the curvature R = 7 mm, the outer edge width A of the outer edge cutout portion 2b is 0.3 mm, the number is 16, and the inner edge width B of the inner edge cutout portion 2c is
0.2 mm, the number of which is 4, while the optical member 3
The artificial cornea 1 made of single crystal alumina was transplanted into the cornea of a rabbit, and these were observed for 6 months for the presence or absence of total ophthalmitis. The results are shown in Table 4.

[0042]

[Table 4]

As is clear from Table 4, it was found that the thickness of the supporting member 2 is preferably 0.025 mm to 0.4 mm.

[Animal Experiment 2] In the artificial cornea 1 as shown in FIG. 3, the support member 2 made of tantalum has a thickness of 0.
The radius R is 2 mm, the curvature R is as shown in Table 5, the outer edge width A of the outer edge cutout portion 2b is 1 mm, and the number is 8, while the optical member 3 is made of PMMA-based synthetic resin. The artificial cornea 1 was transplanted into the cornea of a rabbit, and these were observed for 6 months for the presence or absence of total ocular inflammation.
The results are shown in Table 5.

[0045]

[Table 5]

As is clear from Table 5, it was found that the curvature R of the support member 3 is preferably 5 mm to 9 mm.

[0047]

As described above, in the artificial cornea of the present invention, since the supporting member is made of the above-mentioned metal material which is not harmful to the living body,
Familiar with the corneal tissue, further, by the outer edge notch and the inner edge notch formed in the outer edge portion and the inner edge portion of the support member, to absorb the stress concentrated in a portion of the support member, strain of the support member, Due to deformation and the like, no void is generated between the cornea and the cornea.

Further, since the supporting member is formed into a truncated dome shape, it conforms to the normal shape of the cornea and a part of the main body does not break the cornea and is exposed to the outside. Since a metal material that is not harmful to the body is used, it can be made sufficiently thinner than the cornea, so that there is almost no surgical invasion.

In addition, the outer edge notch and the inner edge notch also play a role of preventing dehydration in the anterior layer caused by separation of the cornea into an anterior layer and a posterior layer, and accompanying nutritional deficiency.

[Brief description of drawings]

FIG. 1 is a perspective view of an artificial cornea according to the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a cross-sectional view of an optical member that constitutes the artificial cornea according to the present invention.

FIG. 4 is a cross-sectional view of an artificial cornea according to the present invention placed within a natural cornea.

FIG. 5 is a plan view of a supporting member constituting the artificial cornea according to the present invention.

FIG. 6 is a cross-sectional view of the artificial cornea according to the present invention.

FIG. 7 is a perspective view of a conventional artificial cornea.

FIG. 8 is a perspective view of a conventional artificial cornea.

[Explanation of symbols]

1 artificial cornea K cornea 2 support member F front layer 2b outer edge cutout N
Rear layer 2c Inner edge notch S
Front chamber 2d Central hole W Aqueous fluid 2e Outer edge portion A Outer edge width 2f Inner edge portion B Inner edge width 2g Outer edge 2h Inner edge 3 Optical member 3a Front surface 3b Rear surface 3c Side surface 3d Step portion 3e Groove

Claims (1)

[Claims] 1. A central hole formed in a thin plate-shaped support member made of a metal material such as pure titanium, titanium alloy, or tantalum for replacing a lost cornea to be used as a cornea substitute, An artificial cornea into which an optical member made of a material is fitted, wherein the supporting member has a truncated dome shape as a whole, and three or more notches are provided at an outer edge portion and / or an inner edge portion thereof. An artificial cornea characterized by having