RU2314074C1 - Surgical method for correcting presbiopia cases aggravated with spherical hypermetropia - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: method involves treating eye cornea with excimer laser radiation in multi-stage mode with optical surfaces and transition zone surface being formed by sequentially layer-by-layer removing cornea segments. Action parameters are wavelength of 193-222 nm pulse power of 0.8-2.1 mJ, laser spot diameter of 0.5-1.5 mm, pulse duration of 5-8 ns, frequency of 30-500 Hz. The first optical surface is spherical concave one having its center in the central optical zone. The second optical surface is formed as spherical concave surface which optical axis coincides with the optical zone center. The second optical surface diameter is 0.28-0.55 times as large as the optical zone diameter. Then, the first transition zone surface is formed as a part of convex external surface of annular toroid being 0.04-0.2 times as large as action zone diameter. External transition zone surface edge is coupled with cornea portion that is not to be withdrawn. The second transition zone surface is formed as a part of concave internal surface of the second annular toroid of the same width. The second internal transition zone surface edge is coupled with external edge of the first optical surface and its external edge is coupled with the first internal transition zone surface edge.

EFFECT: improved visual function in long and short distance; reduced luminous halation; minimized volume of withdrawn eye tissues.

22 dwg

Description

The invention relates to ophthalmology and can be used in the correction of presbyopia in combination with spherical hyperopia. The problem of presbyopia correction in combination with spherical hyperopia is one of the urgent in ophthalmology. Presbyopia is a visual impairment due to old age, is a consequence of the loss of the elastic properties of the lens, which causes a decrease in accommodation and visual impairment near. About 10% of all presbyopes suffer from presbyopia in combination with spherical hyperopia. All this makes the problem of presbyopia correction in combination with spherical hyperopia 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 from 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 required by the patient for professional work near, and the degree of planned anisometropia to create weak myopia in the paired eye are additionally 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 spherical hyperopia in order to provide high visual functions in the distance and near while minimizing the amount 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 spherical hyperopia, including exposure to 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, the first optical surface is initially formed, lying within the entire optical zone (OZ), in the form of a convex spherical surface, which includes the center of the optical zone, by forming niya concentric rings to be removed, centered in the center of the optical zone, containing a Central circular zone, not subject to removal, and increase the area of the Central zone with each removed layer; 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 concave spherical surface, by forming concentric rings that cannot be removed with the center in the center of the optical zone containing the Central circular zone to be removed, and increase the area of the Central zone with each removed layer; then, the first surface of the transition zone (PPZ) is formed, within the area of the impact zone (SV), lying in the range from 0.04 to 0.2 of the diameter of the SV, conjugated by the outer edge of the first PPZ with the corneal area not to be affected, in the form of a part of the convex outer surface (CVP) ) of the first annular toroid formed by the rotation of the first flat segment of a circle turned by the arc of the segment toward the optical axis around the optical axis without intersecting this axis, while the arc of the circle of this segment rests on the chord located under scrap to the optical axis with the optical axis lying in a plane, wherein the first HAG formed by circles, to be removed, with the center at 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, conjugated 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, as a part of the concave inner surface ( FWM) 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 crossing this axis, while the circular arc of this segment is supported on chord disposed at an angle to the optical axis equal to the angle of inclination CHVNP chords, and with the optical axis lying in a 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 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, and a pulse repetition rate of 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 spherical hyperopia to ensure high visual functions in the distance and near without additional spectacle correction while minimizing the volume of removed eye tissue and reducing light halo.

The invention is illustrated by drawings Fig.1-22. 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 corneal exposure zone,

Figure 4 - surface formation 5,

Figure 5 - increase in the area of the circular zone 14,

6 is a structure of a second optical surface 6,

Fig.7 - the formation of the second optical surface,

Fig. 8 is an increase in the area of the central zone 16,

Fig.9 - the formation of the first surface 8 of the transition zone,

Figure 10 is a top view of the surface 8,

11 is an isometric view of the surface 8,

Fig - frontal section of the surface 8,

Fig - the formation of a circular zone 21,

Fig - reduction of the circular zone 22,

Fig - a further decrease in the circular zone 23,

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

Fig is an isometric view of the surface 9,

Fig - frontal section of the surface 9,

Fig - the formation of a circular zone 27,

Figure 20 is a reduction in circular zone 28,

Fig - a further decrease in the circular zone 29,

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 exposing an excimer laser 1 to the cornea of the eye 2 by sequential layer-by-layer removal of sections 3 (FIG. 1) of the cornea 2. On the cornea 2, sections 4 that cannot be removed are formed (Figure 2).

Figure 2 presents:

the first optical surface 5;

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 and 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 cannot be removed.

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 radiation 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 the optical zone 7 is meant the zone in which the optical surfaces 5, 6 are formed (FIG. 3).

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 form the first optical surface 5, lying within the entire optical zone 7, in the form of a convex spherical surface (Figure 2). The surface 5 includes the center 12 of the optical zone 7.

The surface 5 is obtained by forming concentric rings 13 centered in the center 12 of the optical zone 7, bounded by a circle with the radius of the impact zone 11, containing a circular central zone 14, not to be removed (Figure 4). 4, region 14 is not shaded, and the concentric ring 13 is shaded.

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.

With each removed layer, an increase in the area of the central zone 14 and a reduction in the area of zone 13 is performed (Figure 5). 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 5, which allows to obtain high visual functions with near 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 SC lies in the range from 0.28 to 0.55 of the diameter of the SC, in the form of a concave spherical surface (Figure 6). The surface 6 includes the center 12 of the optical zone 7.

The surface 6 is obtained by forming concentric rings 15 centered in the center 11 of the optical zone, bounded by a circle with the radius of the impact zone 11, containing a circular central zone 16 to be removed (Fig.7). In Fig. 7, zone 16 is hatched, and the concentric ring 15 is not hatched.

Zone 16 during laser irradiation is removed during the formation of the first corneal layer of varying shape and each of the subsequent corneal layers of shape required to create the surface 6.

With each removed layer, an increase in the area of the central zone 16 and a reduction in the area of zone 15 is performed (Fig. 8). 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 distance 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 a part of the convex outer (CVP) surface of the first annular toroid (Figure 9). The surface 8 is formed by rotating the first flat segment 17 of the circle, convex towards the optical axis, around the axis 12 of surface 8 without intersecting axis 12. The arc of circle 18 of segment 17 is supported by a chord 19 located at an angle of 20 to axis 12 and lying with an axis of 12 one plane (Fig.9). Top view of surface 8 in FIG. 10. The surface 8 in isometric projection is shown in Fig.11.

The surface 8 is formed by forming circular zones 21 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.

Frontal section of the surface 8, explaining the formation of circular zones 21, is shown in Fig.12. Subsequently, in each layer, the area of the circular zone 21 to be removed is reduced. Positions 22, 23 show a decrease in circular zones 21. Figs. 13, 14, 15 show a layer-by-layer decrease in the area of circular zones 21, 22, 23 (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 as a part of the concave inner surface of the second annular toroid. The surface 9 is formed by rotating the second flat segment 24 of the circle, convex in the direction opposite to the optical axis, around the optical axis 12 without intersecting this axis (Fig. 16). The arc of a circle 25 of segment 24 is based on a chord 26 located at an angle of 20 to axis 12 and lying with axis 12 in the same plane (Fig. 16). The surface 9 in isometric projection is shown in Fig.17.

The surface 9 is formed by forming circular zones 27 to be removed in the range from 0.04 to 0.2 of the diameter of the impact zone.

The frontal section of the surface 9, explaining the formation of circular zones 27, is shown in Fig. 18. Subsequently, in each layer, the area of the circular zone 27 to be removed is reduced (Fig. 18). Positions 28, 29 shows the reduction of circular zones 27 (Fig.20,21). Layer-by-layer reduction in the area of circular zones 27-29 in Figs. 19-21 is shown by shaded areas.

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

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

The excimer laser effect on the cornea, according to the invention, is carried out with the following parameters: the radiation wavelength of the excimer laser is 193-222 nanometers, with a pulse energy 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, frequency pulse repetition from 30 to 500 hertz.

The proposed method is characterized by the following clinical examples.

Example 1

Patient U. 52 years old.

Condition before surgery:

visual acuity into the distance: Vis OD = 0.3 sph + 3.75 D = 1.0;

near visual acuity: Vis OD = 0.3 sph + 5.0 D = 1.0;

corneal curvature: 40.5 D - 90 °, 40.5 D - 0 °, average - 40.5 D;

corneal thickness: 537 microns.

Diagnosis: moderate hyperopia, presbyopia.

The operation LASIK in accordance with the proposed invention.

Condition after surgery:

visual acuity into the distance: Vis OD = 1.0;

near visual acuity: Vis OD = 1.0;

corneal curvature: 44.5 D - 90 °, 44.5 D - 0 °, average - 44.5 D.

Example 2

Patient I. 63 years.

Condition before surgery:

visual acuity into the distance: Vis OS = 0.6 sph + 1.0 D = 1.0;

near visual acuity: Vis OS = 0.1 sph + 3.5 D = 1.0;

corneal curvature: 43.0 D - 90 °, 43.0 D - 0 °, average - 43.0 D;

corneal thickness: 578 microns.

Diagnosis: mild hyperopia, presbyopia.

The operation LASIK in accordance with the proposed invention.

Condition after surgery:

visual acuity into the distance: Vis OS = 1,0;

near visual acuity: Vis OS = 1.0;

corneal curvature: 44.5 D - 90 °, 44.5 D - 0 °, average - 44.5 D.

Example 3

Patient B. 57 years.

Condition before surgery:

visual acuity into the distance: Vis OD = 0.1 sph + 5.0 D = 0.6;

near visual acuity: Vis OD = 0.1 sph + 7.5 D = 0.6;

corneal curvature: 40.0 D - 90 °, 40.0 D - 0 °, average - 40.0 D;

corneal thickness: 534 microns.

Diagnosis: high degree hyperopia, presbyopia.

The operation LASIK in accordance with the proposed invention.

Condition after surgery:

visual acuity into the distance: Vis OD = 0.6;

near visual acuity: Vis OD = 0.5 sph + 0.5 D = 0.6;

corneal curvature: 45.5 D - 90 °, 45.5 D - 0 °, average - 45.5 D.

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

Due to the fact that the edges of surface 5 lie below 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 techniques of removing and not removing curved 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 preservation of 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, provides 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 spherical hyperopia to ensure high visual functions in the distance and near without additional spectacle correction while minimizing the volume of removed eye tissue.

Claims (1)

The method of surgical correction of presbyopia in combination with spherical hyperopia, including the action 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 forming the first optical surface lying within the entire optical zone ( OZ), in the form of a convex spherical surface that includes the center of the optical zone, by the formation of concentrices to be removed rings with a center in the center of the optical zone, containing a central circular zone that cannot be removed, and increase the area of the central zone with each layer to be removed, then form a second optical surface, the optical axis of which coincides with the center of the OZ, 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 concave spherical surface, by the formation of concentric rings not to be removed, centered in the center of the optical zone, containing to be removed the central circular zone, and increase the area of the central zone with each removed layer, then form the first surface of the transition zone (PPZ), lying in the range of 0.04 to 0.2 of the diameter of the pollutant, conjugated by the outer edge with the cornea, not subject to exposure, in as a part of the convex outer surface (CVNP) of the first annular toroid formed by the rotation of an arc of 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 SCF being formed by means of circular zones to be removed with a center in the center of the SC, the outer diameter of which decreases in layers, then form a second SCF lying in the range from 0.04 to 0.2 of the diameter of the conjugate, conjugated by an 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 part of the concave inner surface (CVP) of the second annular toroid formed by rotating the circular arc facing to the side against positive from the optical axis, around the optical axis without its intersection, 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 the optical axis in the same plane, this surface being formed by circular zones to be removed centered at the center of the OZ, the outer diameter of which decreases in layers, and the impact 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 m , 8.5 ns pulse duration, pulse repetition frequency from 30 Hz to 500 Hz.

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