RU2306911C1 - Surgical method for correcting presbyopia combined with simple hypermetropic astigmatism - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: method involves exposing cornea to excimer laser radiation with optical surfaces and transition zone surfaces being formed by means of sequential layer-by-layer removal of cornea areas. Treatment parameters are as follows. Wavelength is 193-222 nm large, impulse power is equal to 0.8-2.1 mJ, laser spot diameter is 0.5-1.5 mm large, pulse duration is equal to 5-8 ns, pulse succession frequency is 30-500 Hz. The first optical surface is shaped as convex ellipsoidal surface belonging to the whole optical zone. Irremovable central elliptic zone is traced when building the surface, elliptic zone symmetry center is superposed with the optical zone center. The greater central elliptic zone axis segment is united with the strong astigmatism axis, the lesser one is united with the weak astigmatism axis. The second optical surface is built as convex spherical surface. Its optical axis coincides with the optical zone center. Ratio between its diameter and optical zone diameter belongs to interval from 0.28 to 0.55. The first surface of the transition zone is built as a portion of convex external surface of the first ring-shaped toroid in a way that it has smooth interface of its external boundary to untreatable cornea portion. The first surface of the transition zone is 0.04-0.2 times as wide as the treatment zone diameter. The second surface of the transition zone of the same width is formed as a portion of the concave external surface of the second ring-shaped toroid. Internal boundary of the second transition zone surface has smooth interface to external boundary of the first optical surface, the external one being conjugated with the internal boundary of the first transition zone surface.

EFFECT: improved vision function in near and far zone; minimized removed eye tissues volume; reduced light halation.

24 dwg

Description

The invention relates to ophthalmology and can be used in the correction of presbyopia in combination with complex hyperopic astigmatism. The problem of presbyopia correction in combination with complex hyperopic astigmatism is one of the urgent in ophthalmology. Presbyopia is understood as a visual impairment due to the achievement of old age, is a consequence of the loss of the elastic properties of the lens, which causes a decrease in accommodation and a decrease in vision near. Complex hyperopic astigmatism is a combination of spherical hyperopia with simple hyperopic astigmatism. About 8% of all presbyopes suffer from presbyopia in combination with complex hyperopic astigmatism. All this makes the problem of presbyopia correction in combination with complex hyperopic astigmatism one of the urgent problems of ophthalmology.

The well-known "Method of surgical correction of presbyopia with refractive errors" according to patent RU No. 2197209, A61F 9/01 priority of 06/06/2000

A method of surgical correction of presbyopia with refractive errors involves exposure to an excimer laser first on the cornea of the lead eye to achieve emmetropic refraction, and then on the cornea of the paired eye until mild myopia is achieved. Additionally, the relative accommodation margin, the positive part of the focal zone of the paired eye, the optimal distance necessary for the patient to work professionally close, are determined, and the degree of planned anisometropia to create weak myopia on the paired eye is determined by the formula

D = 1 / h-0.5 · [POS (A-Fpos) + POS ((Y-35) / 10 + 0.6))],

where h is the optimal distance required by the patient for professional activities near.

However, this method has significant disadvantages: it is not possible to achieve high visual functions while minimizing the amount of tissue removed from the eye, the presence of a significant light halo.

The technical result achieved by the invention is the development of a method for surgical correction of presbyopia in combination with complex hyperopic astigmatism in order to provide high visual functions in the distance and near while minimizing the volume of tissue removed from the eye and reducing the light halo.

The specified technical result is solved by the fact that in the method of surgical correction of presbyopia in combination with complex hyperopic astigmatism, including the effect of excimer laser radiation on the cornea of the eye, optical surfaces and surfaces of the transition zone (PZ) are formed by sequential layer-by-layer removal of cornea sections; initially form the first ellipsoidal convex optical surface lying within the entire optical zone (OZ), by forming a circular impact zone to be removed, and mark the central elliptical zone (CEZ), not to be removed, while the center of symmetry of the CEZ is combined with the center of the optical zone , the major axis of the CEZ is combined with the strong axis of astigmatism, and the minor axis of the CEZ is combined with the weak axis of astigmatism, with each subsequent layer-by-layer exposure, the area of the CEZ not to be removed is increased by the formation of a curved closed figure, bounded by a circle with the radius of the impact zone and a curved line that is the outer part of the CEZ, further increase the area of the CEZ until the major axis of the CEZ are equal to the diameter of the impact zone (SV), then continue to form the optical surface by forming two symmetrical curved closed figures to be removed, each of which is limited by an arc of a circle with the radius of the impact zone and a curved line that is the outer section of the CEZ; then a second optical surface is formed, the optical axis of which coincides with the center of the optical zone, the ratio of the diameter of the second optical surface to the diameter of the SC lies in the range from 0.28 to 0.55 of the diameter of the SC, in the form of a convex spherical surface, by forming concentric rings to be removed , centered at the center of the optical zone, containing a central circular zone not to be removed, and increasing the area of the central zone with each layer to be removed; then form the first surface of the transition zone (PPZ) within the area of the exposure zone (SV), lying in the range from 0.04 to 0.2 of the diameter of the SV connected by the outer edge of the first PPZ with the corneal area not to be affected, in the form of a convex outer part surface (CVNP) of the first annular toroid formed by the rotation of the first flat segment of the circle, facing the segment’s arc towards the optical axis, around the optical axis without intersecting this axis, while the circular arc of this segment rests on the chord located under a gloom to the optical axis and lying with the optical axis in the same plane, the first SCR being formed by circles to be removed, centered in the center of the optical zone, the outer diameter of which decreases in layers; then, a second SCF is formed within the area of the SC, lying in the range from 0.04 to 0.2 of the diameter of the SC connected by the inner edge of the second SCF with the outer edge of the first optical surface, and the outer edge of the second SCF with the inner edge of the first SCF, in the form of a concave part the inner surface (CVI) of the second annular toroid, by rotating the second flat segment of the circle, facing the segment arc in the direction opposite to the optical axis, around the optical axis without intersecting this axis, while the circular arc of this segment is supported I am on a chord located at an angle to the optical axis equal to the angle of inclination of the CVNP chord and lying with the optical axis in the same plane, this surface being formed by circles to be removed, centered in the center of the optical zone, the outer diameter of which decreases in layers; moreover, the effect on the surface of the cornea is produced by the radiation of an excimer laser with a wavelength of 193-222 nanometers with an energy per pulse of 0.8-2.1 millijoules, with a laser spot diameter of 0.5-1.5 mm, a pulse duration of 5-8 nanoseconds, a frequency pulse repetition from 30 to 500 hertz.

The set of essential distinguishing features proposed by the authors is necessary and sufficient for an unambiguous positive solution of the technical problem posed: creating a method for surgical correction of presbyopia in combination with complex hyperopic astigmatism in order to ensure high visual functions in the distance and near without additional spectacle correction while minimizing the volume of removed eye tissue and light halo reduction.

The invention is illustrated by drawings Fig.1-24. They show:

Figure 1 is a frontal section of a radiation exposure zone.

Figure 2 is a frontal section of the location of the optical and transition zones.

Figure 3 is a top view of the impact zone.

Figure 4 - alignment of the axes of astigmatism.

Figure 5 - increase in the area of the elliptical zone 14.

6 - equality of the major axis of the elliptical zone to the diameter of the impact zone.

7 is a decrease in the area of curved shapes 20.

Fig - the structure of the second optical surface 6.

Fig.9 - the formation of the second optical surface.

Figure 10 - an increase in the area of the Central zone 22.

11 - the formation of the first surface 8 of the transition zone.

12 is a plan view of a surface 8.

Fig is an isometric view of the surface 8.

Fig - frontal section of the surface 8.

Fig - the formation of a circular zone 27.

Fig - reduction of the circular zone 28.

Fig - a further decrease in the circular zone 29.

Fig - formation of the second surface 9 of the transition zone.

Fig. 19 is an isometric view of a surface 9.

Fig - frontal section of the surface 9.

Fig - the formation of a circular zone 33.

Fig - reduction of the circular zone 34.

Fig - a further decrease in the circular zone 35.

Fig is an isometric view of the mating surfaces 8 and 9.

The method proposed by the authors is as follows.

The method consists in the exposure of the excimer laser 1 to the cornea of the eye 2 by successive layer-by-layer removal of sections 3 (Figure 1) of the cornea 2. On the cornea 2, sections 4 are formed that cannot be removed (Figure 2).

Figure 2 presents:

The first optical surface 5;

The second optical surface 6;

Optical zone 7;

The first surface 8 of the transition zone;

The second surface 9 of the transition zone;

Transition Zone 10.

Figure 2 dots show the boundaries of the surfaces 5, 6, 8, 9, 4.

By a part of the surface of the cornea 2 to be removed is meant a portion of the cornea of a certain shape that is exposed to laser radiation 1, removed as a result of this effect.

By a part of the surface of the cornea that cannot be removed is meant a portion of the cornea of a certain shape that is not exposed to laser radiation and is not removable.

By optical surface is meant the interface between two media with different refractive indices, which serves to change the path of the rays when creating a high-quality optical image on the retina of the eye.

By a layer of the cornea is meant a portion of the cornea, the shape of which changes upon a single exposure to a spatially ordered series of laser pulses.

A top view of the exposure zone is shown in FIG. 3. Surfaces 5, 6, 8, 9 are shown in FIGS. 2, 3:

By optical zone 7 is meant a zone in which optical surfaces 5, 6 are formed (FIG. 3);

Under the transition zone 10 refers to the surface 8 and 9, performing the function of smoothly connecting the optical surface 5 with a portion 4 of the cornea 2, which is not produced by laser exposure.

The impact zone 11 refers to the zone in which the optical surfaces and the surfaces of the transition zone are formed.

The optical axis 12 is the axis of symmetry of all formed optical surfaces and the surfaces of the transition zones (Fig.2, 3).

The optical surfaces 5, 6 and the surfaces of the transition zone 8, 9 are formed by sequential layer-by-layer removal of corneal regions. There are also sections 4 of the cornea 2, not to be removed, located on the periphery of the cornea.

The implementation of the method should be divided into several stages.

Initially, the first ellipsoidal convex optical surface 5 is formed, lying within the entire optical zone 7, by forming the zone 13 to be removed.

Mark the central elliptical zone 14 (CEZ), not subject to removal (Figure 4). 4-7, region 14 is not shaded, and zone 13 is shaded.

The center of symmetry of the CEZ is combined with the center 12 of the optical zone 7, the major axis 15 of the CEZ is combined with the strong axis of astigmatism 16, and the minor axis 17 of the CEZ is combined with the weak axis of astigmatism 18 (Figure 4). Zone 14 during laser irradiation is not removed during the formation of the first corneal layer that changes in shape and each of the subsequent cornea that changes in shape to create a surface 5.

Figure 4 shows, for convenience of presentation, the case where the strong axis 16 of astigmatism is vertical and the weak axis 18 is horizontal. In practice, cases with a different arrangement of the axes of astigmatism are possible (not shown in the figure).

With each of the subsequent laser actions, the area of the CEZ 14 increases, and the area 13 decreases. In this case, zone 13 is formed by a curved closed figure bounded by a circle with the radius of the impact zone 11 and a curved line 19, which is the outer section of the CEZ (Figure 5). With each subsequent layer-by-layer exposure, the area of the CEZ 14, which cannot be removed, is increased, and the area of the curved closed figure 13 is reduced (Figure 5).

The area of the CEZ, not subject to removal, is increased until the equality of the major axis 15 of the CEZ with the diameter of the impact zone 11 (Fig.6). In this case, the curvilinear zone to be removed forms two symmetric curvilinear closed figures 20, each of which is bounded by an arc of a circle 11 with the radius of the zone of influence and a curved line 19, which is the outer part of the CEZ 14. In FIG. 6, two symmetrical closed figures 20 are shaded.

The formation of the optical surface is continued by the formation of the CEZ 14, which cannot be removed, and two symmetrical curved closed figures 20, which must be removed. With each subsequent layer, the area of the CEZ 14, not to be removed, is increased, and the area of the curved closed figures 20 to be removed is reduced (Fig.6, 7). Each of the curved closed figures 20 is bounded by an arc of a circle 11 with the radius of the zone of influence and a curved line 19, which is the outer section of the CEZ 14 (Fig.7). Surface 5 allows you to get high visual functions with distance vision.

Then form the second optical surface 6, the optical axis of which coincides with the center of the optical zone, the ratio of the diameter of the second optical surface to the diameter of the OZ lies in the range from 0.28 to 0.55 of the diameter of the OZ, in the form of a convex spherical surface (Fig. 8). The surface 6 includes the center 12 of the optical zone 7.

The surface 6 is obtained by forming concentric rings 21 centered in the center of the optical zone, bounded by a circle with the radius of the impact zone 11, containing a circular central zone 22 that cannot be removed (Fig. 9). 9, zone 22 is not shaded, and the concentric ring 21 is shaded.

Zone 22 during laser irradiation is not removed during the formation of the first corneal layer that changes in shape and each of the subsequent cornea that changes in shape to create a surface 6.

With each removed layer, an increase in the area of the central zone 22 and a reduction in the area of zone 21 are performed (Figure 10). The spatial combination of all circular layers of the cornea that cannot be removed, in which the diameter of the subsequent layer of the cornea is larger than the diameter of the previous one, creates a convex spherical optical surface. Surface 6 allows you to get high visual functions with near vision.

Then form the surface 8, 9 of the transition zone, which are the surfaces of the annular toroids. An annular toroid means a surface formed by the rotation of a circle around an optical axis without intersecting this axis. In the present invention, surfaces 8, 9 are parts of a circular toroid and are formed by rotating segments of a circle around an optical axis without intersecting this axis.

The first surface 8 of the transition zone is formed as part of the convex outer (CVP) surface of the first annular toroid (Figure 11). The surface 8 is formed by rotating the first flat segment 23, convex towards the optical axis, around the axis 12 of surface 8 without intersecting axis 12. The arc of circle 24 of segment 23 is supported by a chord 25 located at an angle 26 to axis 12 and lying with axis 12 in one plane (Fig.11). Top view of the surface 8 in Fig.12. The surface 8 in isometric projection is shown in Fig.13.

The surface 8 is formed by forming circular zones 27 to be removed, bounded by a circle with a radius of the impact zone 11, with a center 12, in the range from 0.04 to 0.2 of the diameter of the impact zone.

A frontal section of the surface 8, explaining the formation of the circular zones 27, is shown in FIG. 14. Subsequently, in each layer, the area of the circular zone 27 to be removed is reduced. Positions 28, 29 show a decrease in circular zones 27. Figs 15, 16, 17 show a layer-by-layer decrease in the area of circular zones 27, 28, 29 (shaded in the figures).

The surface of the transition zone 8 is mated with a portion of the cornea 4, not subject to laser exposure.

Then form the second surface 9 of the transition zone in the form of a portion of the concave inner surface (CVP) of the second annular toroid. The surface 9 is formed by the rotation of the second flat segment 30, facing the opposite side from the optical axis, around the optical axis 12 without intersecting this axis (Fig. 18). The arc of a circle 31 of segment 30 is supported by a chord 32 located at an angle of 26 to the optical axis 12 of the CVT of the second toroid (Fig. 18). The surface 9 in isometric projection is shown in Fig.19.

The surface 9 is formed by forming circular zones 33 to be removed in the range from 0.04 to 0.2 of the diameter of the impact zone.

A frontal section of the surface 9 explaining the formation of the circular zones 33 is shown in FIG. 20. Subsequently, in each layer, the area of the circular zone 33 to be removed is reduced. Positions 34, 35 show the reduction of circular zones 33 (Fig.21-23). Layer-by-layer reduction in the area of circular zones 33-35 in figures 21-23 is shown by shaded areas.

The second surface of the transition zone 8 is mated with the first surface 9 of the transition zone. An isometric view of this interface is shown in FIG.

It should be noted that the inner edge of the CVP is combined with the outer edge of the CVP, and the inner edge of the CVP is combined with the outer edge of the optical surface 5.

The excimer laser action on the cornea according to the invention is carried out with the following parameters: excimer laser radiation wavelength of 193-222 nanometers with an energy per pulse of 0.8-2.1 millijoules, with a laser spot diameter of 0.5-1.5 mm, with a pulse duration of 5 -8 nanoseconds, pulse repetition rate from 30 to 500 hertz.

The proposed method is characterized by the following clinical examples.

Example 1: Patient X. 52 years old.

Condition before surgery:

Visual acuity in the distance: Vis OD = 0.2 sph + 2.0 D cyl + 4.25 D ax 95 ° = 0.8

Near visual acuity: Vis OD = 0.1 sph + 4.0 D cyl + 4.25 D ax 95 ° = 0.8

Corneal curvature: 42.25 D - 95 °, 38.00 D - 05 °, average - 40.00 D.

Corneal thickness: 525 microns.

Diagnosis: Complex hyperopic astigmatism of a high degree, presbyopia.

The operation in accordance with the proposed invention.

Condition after surgery:

Visual acuity in the distance: Vis OD = 0.7 sph-0.5 D cyl + 1.0 D ax 90 ° = 0.8

Near visual acuity: Vis OD = 0.8

Corneal curvature: 44.5 D - 90 °, 43.5 D - 0 °, average - 44.00 D.

Example 2: Patient A. 63 years.

Condition before surgery:

Visual acuity in the distance: Vis OD = 0.4 sph + 2.5 D cyl + 1.75 D ax 87 ° = 1.0

Near visual acuity: Vis OD = 0.1 sph + 5.5 D cyl + 1.75 D ax 87 ° = 1.0

Corneal curvature: 43.25 D - 87 °, 41.50 D - 177 °, average - 42.35 D.

Corneal thickness: 548 microns.

Diagnosis: Complicated mild hyperopic astigmatism, presbyopia.

The operation in accordance with the proposed invention.

Condition after surgery:

Distance Visual Acuity: Vis OD = 1.0

Near visual acuity: Vis OD = 0.9

Corneal curvature: 45.75 D - 90 °, 46.0 D - 0 °, average - 45.85 D.

Example 3: Patient M., 57 years old.

Condition before surgery:

Visual acuity in the distance: Vis OS = 0.5 sph + 2.0 D cyl + 2.5 D ax 110 ° = 1.0

Near visual acuity: Vis OS = 0.2 sph + 4.0 D cyl + 2.5 D ax 110 ° = 1.0

Corneal curvature: 41.5 D - 110 °, 39.0 D - 20 °, average - 40.25 D.

Corneal thickness: 534 microns.

Diagnosis: Moderate hypermetropic astigmatism, presbyopia.

The operation in accordance with the proposed invention.

Condition after surgery:

Visual acuity in the distance: Vis OS = 1.0

Near visual acuity: Vis OS = 1.0

Corneal curvature: 43.5 D - 90 °, 43.5 D - 0 °, average - 43.5 D.

The presence of surfaces 5, 6 provides high visual functions with near and far vision.

Due to the fact that the edges of the surface 5 lie below the surface 4, it is necessary to form a smooth transition between the optical surface 5 and the area of the cornea 4. This role is played by the surfaces 8, 9 of the transition zone 10, made in accordance with the claims. The implementation of these surfaces in this form allows you to form a smooth transition between surfaces 5 and 4 and prevent the occurrence of the effect of a circular halo.

Minimization of the volume of removed tissue of the eye is achieved by the whole set of technological methods for performing a spatial effect on the cornea of the eye by simultaneously combining the methods of removing and not removing curvilinear shapes in each layer of the cornea with each exposure and the logically necessary combination of these techniques in each subsequent layer to create each of the optical surfaces 5, 6, the surfaces of the transition zone 8, 9 and maintaining the integrity of the surface 4 on the periphery of the cornea.

The whole set of essential distinguishing features of the invention indicated in the claims, including radiation parameters, provide an unambiguous positive solution to the claimed technical problem.

The use of the invention in the Federal State Institution IRTC “Eye Microsurgery” named after Acad. S.N. Fedorova made it possible to confirm an unambiguous positive solution to the stated technical problem, the development of a method for surgical correction of presbyopia in combination with complex hyperopic astigmatism to ensure high visual functions in the distance and near without additional spectacle correction while minimizing the volume of removed eye tissue.

Claims (1)

A method of surgical correction of presbyopia in combination with complex hyperopic astigmatism, including the effect of excimer laser radiation on the cornea of the eye, characterized in that the optical surfaces and the transition zone surfaces are formed by sequential layer-by-layer removal of cornea sections; initially form the first ellipsoidal convex optical surface lying within the entire optical zone (OZ) by forming a circular impact zone to be removed, and mark the central elliptical zone (CEZ) not to be removed, while the center of symmetry of the CEZ is combined with the center of the optical zone, a large the axis of the CEZ is combined with the strong axis of astigmatism, and the small axis of the CEZ is combined with the weak axis of astigmatism, with each subsequent layer-by-layer exposure, the area of the CEZ is increased, with the first ellipsoidal a convex optical surface is formed by forming a curvilinear closed figure to be removed, bounded by a circle with a radius of the impact zone and a curved line that is the outer part of the CEZ, then increase the area of the CEZ until the major axis of the CEZ are equal to the diameter of the impact zone (3B), then continue to form the optical surfaces by forming two symmetrical curvilinear closed figures to be removed, each of which is bounded by an arc of a circle with a radius of actions and a curved line, which is the outer section of the CEZ; then a second optical surface is formed, the optical axis of which coincides with the center of the optical zone, the ratio of the diameter of the second optical surface to the diameter of the SC lies in the range from 0.28 to 0.55 of the diameter of the SC, in the form of a convex spherical surface, by forming concentric rings to be removed from a center in the center of the optical zone containing a non-removable central circular zone and increase the area of the central zone with each layer to be removed; then form the first surface of the transition zone (PPZ), lying in the range of 0.04 to 0.2 of diameter 3B, conjugated by the outer edge with a portion of the cornea not subject to impact, in the form of a part of the convex outer surface (CVP) of the first annular toroid formed by the rotation of the arc a circle facing the optical axis, around the optical axis without its intersection, while the arc is supported by a chord located at an angle to the optical axis and lying with the optical axis in the same plane, the first PPZ being formed by circles near those that are removed, centered in the center of the optical zone, the outer diameter of which decreases in layers; then form the second PPZ, lying in the range from 0.04 to 0.2 of diameter 3B, conjugated by the inner edge with the outer edge of the first optical surface, and the outer edge with the inner edge of the first PPZ, in the form of a portion of the concave inner surface (FVP) of the second annular a toroid formed by the rotation of an arc of a circle facing the opposite direction from the optical axis around the optical axis without intersecting it, while the arc rests on a chord located at an angle to the optical axis equal to the angle of inclination of the CVNP chord, and lying with optically axis in one plane, wherein this surface is formed by circles, to be removed, with the center at the center of the optical zone, the outer diameter of which decreases in layers; moreover, the effect on the surface of the cornea is produced by the radiation of an excimer laser with a wavelength of 193-222 nm, with an energy per pulse of 0.8-2.1 mJ, with a laser spot diameter of 0.5-1.5 mm, pulse duration of 5-8 ns, pulse repetition rate from 30 to 500 Hz.

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