RU2120267C1 - Method of manufacture of biological lenses from donor cornea - Google Patents

Abstract

FIELD: medicine, ophthalmology. SUBSTANCE: after cutting of biological lens by knife for value of not less than diameter of lens being manufactured it is placed on support with surface of shear directed upwards. Biological lens is cut off in process of donor cornea rotation about its optical axis. Radius of the above- indicated support is selected to be equal to radius of cut-off BIOLOGICAL lens. Then circular incision is made with trepan, at least 3 mm in diameter, to depth calculated by formula:

, where ΔH is trepanation depth; H is biological lens thickness; R₁ is curvature radius of rated required biological lens; D is diameter of biological lens optical zone. This done, cornea tissue is removed by separator over entire perimeter of biological lens from edge up to trepanation depth. EFFECT: extended range of biological lens force from 0 to +25D. 4 dwg

Description

 The invention relates to medicine, namely to ophthalmology, and can be used for refractive keratoplasty.

 A known method of manufacturing biological lenses from a donor cornea (see in the book. Am.J. Ophtalmol., 1989, 107, N 1, S. 47-50). The essence of the method consists in cutting off the layers of the cornea with laser beams during the rotation of the donor cornea around its optical axis. The disadvantage of this method is the duration of cutting a biological lens (8-10 min), which leads to the drying of the donor cornea and its sheared part. Drying, in turn, leads to pathological changes in the cells of the corneal tissue, which dramatically increases the risk of transplant rejection, to deformation and distortion of the calculated optical parameters of the cut biological lens.

 A significant drawback of this method is the need to use hard-to-reach and very expensive (at least $ 30,000) eximer laser equipment. Domestic medicine does not have such equipment, and its widespread use is not expected in the foreseeable future.

 The closest in technical essence is a method of manufacturing biological lenses from an unreserved donor cornea (ed. St. N 1773400 A1, A 61 F 9/00), adopted as a prototype. A biological lens is made by cutting layers of the donor cornea in the process of rotating it around its optical axis with a knife with a width and length not less than the diameter of the cut surface. Theoretically, the maximum strength of a biological lens can reach 22.24 D, however, positive lenses with a refractive power of not more than + 12.0 D are made in this way.

 We set the task of expanding the range of strength of manufactured biological lenses.

где ΔH - глубина трепанации;
H - толщина биологической линзы;
R₁- радиус кривизны расчетной необходимой биолинзы;
D - диаметр оптической зоны биологической линзы,
после чего расслаивателем удаляют роговичную ткань по всему периметру биологической линзы от края биологической линзы до глубины трепанации.To solve this problem, a method for the manufacture of biological lenses from a donor cornea is proposed, which consists in the fact that after cutting the biological lens during rotation of the donor cornea around its optical axis with a knife of at least the diameter of the manufactured lens, it is laid with the cutting surface up on a stand with a radius equal to the radius of the cut biological lenses, then a trepan with a diameter of at least 3 mm make a circular incision to a depth calculated by the formula

where ΔH is the depth of trepanation;
H is the thickness of the biological lens;
R ₁ is the radius of curvature of the estimated required biolins;
D is the diameter of the optical zone of the biological lens,
after which the corneal tissue is removed with a delaminator along the entire perimeter of the biological lens from the edge of the biological lens to the depth of trepanation.

 The proposed method allows to obtain biological lenses with a power of up to +25 D, which is achieved by significantly reducing the radius of curvature of the front surface of the biological lens.

 In FIG. 1 shows a donor cornea; in FIG. 2 - biological lens after cutting the donor cornea; in FIG. 3 - biological lens after removal of corneal tissue along the entire perimeter of the biolins; in FIG. 4 - biological lens, hemmed to the cornea of the patient.

где ΔH - глубина трепанации;
H - толщина биологической линзы;
R₁ - радиус кривизны расчетной необходимой биолинзы;
D - диаметр оптической зоны биологической линзы.The proposed method is as follows. A flat-convex biological lens is cut from a donor cornea in the process of rotating it around its axis with a knife with a width and a length not less than the diameter of the manufactured lens. The resulting biological lens is placed with the cutting surface up on a support with a radius equal to the radius of the cut biological lens. A trepan with a diameter of at least 3 mm make a circular incision to a depth calculated by the formula

where ΔH is the depth of trepanation;
H is the thickness of the biological lens;
R ₁ is the radius of curvature of the estimated required biolins;
D is the diameter of the optical zone of the biological lens.

 After that, the corneal tissue is removed with a delaminator along the entire perimeter of the biological lens from the edge of the biological lens to the depth of trepanation.

 The method is illustrated by the following example.

 Patient K; 19 years old, diagnosis: OD - aphakia.

 Visual acuity of the right eye: 0.04 with correction +15.0 D = 0.7.

 Ophthalmometry: 42.25 85 g., 42.75 120 g.

 The size of the anteroposterior axis of the eye is 23.40 mm.

 To correct the aphakia of this patient with corneal refraction - 42.5 D and PZO - 23.40 mm, a plano-convex biological lens was machined with a thickness of 0.3 mm and a diameter of 7 mm on a modulating base with a radius of curvature of 19 mm.

После чего расслаивателем удалили роговичную ткань по всему периметру биологической линзы от ее края до глубины трепанации. Через 2 месяца после операции, в результате подшивания полученной биолинзы на роговицу реципиента, рефракция правого глаза больного: -1,0 D, офтальмометрия - 56,25 D. В данном случае изменение рефракции глаза больного составило 16,0 D.For the manufacture of a concave-convex biological lens, the obtained lens is laid up with the cutting surface up on a support with a radius equal to the radius of the cut biological lens, then a trepan with a diameter of 3 mm is made into a circular trepanation to a depth of 0.1 mm, calculated by the formula

After that, corneal tissue was removed with a delaminator along the entire perimeter of the biological lens from its edge to the depth of trepanation. 2 months after the operation, as a result of suturing the obtained biolens onto the recipient’s cornea, the patient’s right eye refraction: -1.0 D, ophthalmometry - 56.25 D. In this case, the patient’s eye refraction was 16.0 D.

 Thus, the clinical results allow us to conclude that the proposed method for the manufacture of biological lenses allows us to achieve the goal, namely, to achieve the correction of aphakia and hyperopia of high degree above +12 D and, thus, to provide a higher functional result of the operation.

Claims (1)

A method of manufacturing biological lenses from a donor cornea by cutting its layers during rotation around its optical axis with a knife with a width and length not less than the diameter of the manufactured lens, characterized in that the cut layer of the biological lens is laid with the cutting surface up on a stand with a radius equal to the radius of the cut biological lens then a trepan with a diameter of at least 3 mm make a circular incision to a depth calculated by the formula

Where
ΔH- is the depth of trepanation;
H is the thickness of the biological lens;
R ₁ is the estimated radius of curvature of the convex surface of the biological lens;
D is the diameter of the optical zone of the biological lens,
whereupon the corneal tissue is removed along the entire perimeter from the edge of the biological lens to the depth of trepanation with a stratifier.

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