RU2514874C1 - Method for surgical correction of presbyopy combined with spherical hypermetropia - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: eye cornea is exposed to an eximer laser light at wave length 193-222 nm, pulse energy 0.8-2.1 mJ, laser spot diameter 0.5-1.5 mm, pulse length 5-8 nm, pulse repetition frequency 30 to 500 Hz. This expose aiming at a sequential corneal abrasion is combined with forming optical surfaces and transition surfaces. A first spherical convex optical surface is formed within the entire optical cornea (OC), including the OC centre. A second optical surface is formed as a convex ellipsoid of rotation with a positive conic constant within +0.75 to +1.5. An optical axis of the second optical surface matches with the OC centre. A diameter of the second optical surface is related to an OC diameter as a value within the range of 0.85 to 0.95. Then, the transitions surfaces (TS) are formed. The first TS is formed as a portion of a convex outer surface of a first O-toroid. The second TS is formed as a portion of a concave inner surface of a second O-toroid. The second TS is formed so that its inner border is coupled with an outer border of the first optical surface. The outer border of the second TS shall be coupled with the inner border of the first TS.EFFECT: method enables minimising the amount of the resected eye tissue, provides the high far and near visual functions with no additional spectacle correction with decreased light cap.22 dwg, 3 ex

Description

The invention relates to ophthalmology and can be used in the correction of presbyopia with spherical hyperopia. The problem of presbyopia correction in combination with spherical hyperopia is one of the urgent in ophthalmology. Presbyopia is an age-related decrease in the volume of accommodation caused by the loss of the elastic properties of the lens and leading to decreased vision near and difficulty working at close range. About 10% of all presbyopes suffer from presbyopia in combination with spherical hyperopia. 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 in combination with spherical hyperopia" according to patent RU No. 2314074, A61F, 9/01 priority from 04/26/2011

The method of surgical correction of presbyopia with spherical hyperopia involves the action of radiation of an excimer laser on the cornea of the eye with the formation in several stages of optical surfaces and the surface of the transition zone (PZ) by layer-by-layer removal of cornea.

The first optical surface has the form of a convex spherical surface centered in the center of the optical zone (OZ). The second optical surface has the form of a concave spherical surface, its diameter is 0.28-0.55 diameter OZ, and its optical axis coincides with the center of the OZ. The first surface of the PPZ is formed as part of the convex outer surface of the first annular toroid with a width of 0.04-0.2 diameter of the impact zone. The outer edge of the first PPA is mated with a section of the cornea that is not subject to exposure. The second PPZ is formed as part of the concave inner surface of the second annular toroid of the same width. The inner edge of the second PPZ mate with the outer edge of the first optical surface, and the outer edge with the inner edge of the first PPZ.

However, this method has some disadvantages: the presence of a significant light halo, as well as the restoration of visual acuity for a distance more than for close.

The objective of the invention is to develop a method for surgical correction of presbyopia in combination with spherical hyperopia in order to provide high visual functions in the distance and near, as well as reduce the light halo.

The technical result achieved by the invention is to reduce the halo of light, as well as the restoration of vision for both far and near.

The specified technical result is achieved by the fact that in the method of surgical correction of presbyopia in combination with spherical hyperopia, including exposure to excimer laser radiation with a wavelength of 193-222 nm, an energy per pulse of 0.8-2.1 mJ, a laser spot diameter of 0.5 1.5 mm, a pulse duration of 5-8 ns, a pulse repetition rate of 30 to 500 Hz to the cornea of the eye with the formation of two optical surfaces, the first optical surface lying within the entire optical zone (OZ) is formed in the form of a convex spherical surface STI, then form a second optical surface, then form the surface of the transition zone: a first surface of the transition zone (HAG), conjugated with the outer edge portion of the cornea is not subject to impact, is formed as part of the convex outer surface (CHVNP) of the first annular toroid; the second PPZ, 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, is formed as part of the concave inner surface (CVP) of the second annular toroid; according to the invention, the second optical surface is formed in the form of a convex ellipsoid of revolution with a positive conical constant from +0.75 to +1.5, while the ratio of the diameter of the second optical surface to the diameter of the SC lies in the range from 0.85 to 0.95 of the diameter of the SC .

The decrease in the halo of light occurs due to the fact that the second optical surface has the form of a convex ellipsoid of revolution and the ratio of its diameter to the diameter of the SC lies in the range of 0.85 to 0.95 of the diameter of the SC; restoration of vision both far and near is provided by the formation of two optical surfaces, despite the fact that the second optical surface has the shape of a convex ellipsoid with a positive conical constant from +0.75 to +1.5.

The set of essential distinguishing features proposed by the authors is necessary and sufficient for an unambiguous positive solution of the technical problem posed: the creation 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 reducing the 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 area of the cornea.

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.

12 is a frontal section through a 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.

17 is an isometric view of a surface 9.

Fig. 18 is a frontal section through a surface 9.

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 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;

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 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 optical zone 7 is meant a zone in which 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 distance vision.

Then the second optical surface 6 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 0.85 to 0.95 of the diameter of the SC, in the form of a convex ellipsoid of revolution with a positive conical constant of +0 , 75 to +1.5 (Fig.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 that cannot be removed (Fig. 7). In Fig. 7, zone 16 is not shaded, and the concentric ring 15 is shaded.

Zone 16 during laser irradiation is not removed during the formation of the first corneal layer that changes in shape and each of the subsequent corneal layers that are required to create a 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 an optical surface in the form of a convex ellipsoid of revolution. 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 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.

A frontal section of the surface 8, explaining the formation of the 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 shows the reduction of the circular zones 21. FIG. 13, 14, 15 show a layered 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 the formation of circular zones 27 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 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. 19). 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 figures 19-21 is shown in 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 CVPI is combined with the outer edge of the CVPP, and the inner edge of the CVPN is combined with the outer edge of the optical surface 5.

Excimer laser effect on the cornea is carried out with the following parameters:

The radiation wavelength of an 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, and a pulse repetition rate of 30 to 500 hertz.

The proposed method is characterized by the following clinical examples.

Example 1: Patient A. 53 years.

Condition before surgery:

Visual acuity in the distance: Vis OD = 0.5 sph + 3.0 D = 1.0

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

Corneal curvature: 41.0 D - 95 °, 41.0 D - 5 °, average - 41.0 D.

Corneal thickness: 562 microns.

Diagnosis: moderate hypermetropia, presbyopia.

The operation LASIK in accordance with the proposed invention.

Condition after surgery:

Distance Visual Acuity: Vis OD = 1.0

Near visual acuity: Vis OD = 0.7 Sph + 1.0 D = 1.0

Corneal curvature: 44.0 D - 90 °, 44.0 D - 0 °, average - 44.0 D.

Example 2: Patient B. 56 years.

Condition before surgery:

Visual acuity in the distance: Vis OS = 0.1 sph + 4.25 D = 0.9

Near visual acuity: Vis OS = 0.1 sph + 6.25 D = 0.9

Corneal curvature: 40.25 D - 100 °, 40.25 D - 10 °, average - 40.25 D.

Corneal thickness: 551 microns.

Diagnosis: High degree hypermetropia, presbyopia.

The operation LASIK in accordance with the proposed invention.

Condition after surgery:

Visual acuity in the distance: Vis 08 = 0.8

Near visual acuity: Vis OS = 0.7 sph + 0.5 D = 0.8

Corneal curvature: 45.0 D - 90 °, 45.0 D - 0 °, average - 45.0 D.

Example 3: Patient C. 61 years.

Condition before surgery:

Visual acuity in the distance: Vis 08 = 0.5 sph + 2.5 D = 1.0

Near visual acuity: Vis 08 = 0.1 sph + 4.5 D = 1.0

Corneal curvature: 43.0 D - 90 °, 43.0 D - 0 °, average - 44.0 D.

Corneal thickness: 549 microns.

Diagnosis: mild hypermetropia, presbyopia.

The operation LASIK in accordance with the proposed invention.

Condition after surgery:

Visual acuity in the distance: Vis 08 = 1,0

Near visual acuity; Vis 08 = 0.8 sph + 1.0 D = 1.0

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.

Features of the second optical surface: its shape in the form of a convex ellipsoid of revolution with a positive conical constant from + 0.75 to + 1.5 and a fairly wide diameter from 0.85 to 0.95 of the diameter of the OZ; reduce the effect of a circular halo.

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 FSBI MNTK "Eye Microsurgery" them. Acad. S.N. Fedorov 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.

Claims (1)

A method of surgical correction of presbyopia in combination with spherical hyperopia, including exposure to excimer laser radiation with a wavelength of 193-222 nm, pulse energy of 0.8-2.1 mJ, laser spot diameter of 0.5-1.5 mm, pulse duration 5 -8 ns, the pulse repetition rate from 30 to 500 Hz on the cornea of the eye with the formation of two optical surfaces: the first optical surface lying within the entire optical zone (OZ) is formed in the form of a convex spherical surface, then the second optical surface is formed, after e form of transition surface areas: a first surface of the transition zone (HAG) conjugate with an outer edge portion of the cornea is not subject to impact, is formed as part of the convex outer surface (CHVNP) of the first annular toroid; the second PPZ, 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, is formed as part of the concave inner surface (CVP) of the second annular toroid; characterized in that the second optical surface is formed in the form of a convex ellipsoid of revolution with a positive conical constant from +0.75 to +1.5, while the ratio of the diameter of the second optical surface to the diameter of the SC lies in the range from 0.85 to 0.95 of the diameter OZ.

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