RU2780271C1 - Orthokeratological lens to slow down the development of myopia - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to ophthalmology. An orthokeratological lens for slowing the development of myopia contains a convex anterior surface and a concave posterior surface facing, when using the lens, to the patient’s eye, and contains a central optical zone, an annular return zone surrounding the central optical zone, and an annular recess adjacent on one side to the central circular optical zone and, on the other to the annular return zone.

EFFECT: application of this invention will provide the formation of a controlled deep myopic peripheral defocus to stabilize progressive myopia for patients with mild and moderate myopia.

6 cl, 3 tbl, 6 dwg

Description

The present invention relates to ophthalmology, to contact lenses, and more specifically to an orthokeratology lens for slowing the development of myopia.

Orthokeratology lenses, per se, are widely known. Orthokeratology lenses are night lenses. These lenses help to correct vision for nearsightedness, farsightedness and astigmatism without surgery and glasses. Orthokeratology lenses are stiffer than conventional soft contact lenses, and have a geometric shape that is selected based on the parameters of the cornea and refraction of a particular patient. These lenses are safe for human eyes, as they affect only the epithelial cells of the cornea (the upper layer of the cornea), without touching them and without damaging the eye. The lens and the sub-lens layer have a hydraulic effect on moisture inside the epithelial cells, due to which moisture is redistributed, the central cells become flat, and convex on the periphery, as a result of which an annular tubercle forms on the cornea of the eye, which essentially works as a positive lens and forms eye peripheral myopic defocus. Ultimately, the use of orthokeratology lenses leads to a slowdown in the development of myopia.

Most orthokeratological lenses contain a central optical zone having a spherical shape, and an annular optical return zone adjacent to the central optical zone, also having a spherical shape. Moreover, in known orthokeratological lenses, the radius of curvature of the central optical zone is greater than the radius of curvature of the annular return zone. In addition to these zones, the orthokeralogical lens contains an annular support zone adjacent to the optical return zone and designed to hold the lens on the patient's eye in the correct position, and an annular edge zone adjacent to the support zone and designed to ensure tear exchange in the sub-lens space.

Despite a number of advantages, traditional orthokeratological lenses of traditional design also have disadvantages.

Our practice of using traditional orthokeratological lenses has shown their low effectiveness in controlling mild to moderate progressive myopia, since the design of these lenses does not provide deep myopic peripheral defocus, which is responsible for stabilizing progressive myopia, and this is due precisely to the fact that the lens obtained on the cornea of the eye the annular tubercle has insufficient optical power.

The invention is based on the task of creating a new orthokeratological lens to slow the development of myopia, the design of which will allow the formation of a controlled deep myopic peripheral defocus to stabilize progressive myopia for patients with mild and moderate myopia.

This problem is solved in an orthokeratological lens to slow the development of myopia, containing a convex anterior surface and a concave posterior surface facing, when using the lens, the patient's eye, and containing a central optical zone, an annular return zone surrounding the central optical zone, and an annular recess adjacent , on the one hand, to the central circular optical zone and, on the other hand, to the annular return zone.

In the claimed orthokeratological lens, an annular tubercle is also formed on the cornea of the eye, but unlike the traditional orthokeratological lens, the position, size and optical power of the annular tubercle formed on the cornea of the eye is set by the position and parameters of the annular recess provided in the claimed orthokeratological lens, i.e. . in other words, when manufacturing a lens, we can set the position of the recess in the lens, as well as its depth, and thus, based on the structural features of the eye of a particular patient, we can set for this particular patient the position of the place where the annular tubercle is formed on the cornea of the eye and its dimensions. The process of formation of an annular tubercle becomes controlled by an ophthalmologist. In addition, our research and practice of using the proposed lens for patients with mild and moderate myopia showed that the annular tubercle formed as a result of the use of such a lens has a greater optical power compared to the tubercle formed as a result of the use of an orthokeratological lens of a traditional design, and this is achieved. precisely by optimizing the location of the annular tubercle on the cornea of the patient's eye and its size.

Thus, the claimed orthokeratological lens allows you to create a controlled deep myopic peripheral defocus to stabilize progressive myopia for patients with mild to moderate myopia.

The central optical zone of the lens can have a different shape and profile depending on the parameters of the patient's eye, but our practice has shown that lenses in which the central optical zone is a round spherical surface are suitable for the vast majority of patients.

Less often there is a need for lenses in which the central optical zone is a round toric surface.

At present, we are already manufacturing orthokeratological lenses of the claimed design, in which the annular recess is formed by an annular spherical surface or an annular conical surface or an annular toric surface. The choice of the shape of the annular recess for a particular patient depends on the geometric and other parameters of his eye.

If we manufacture a lens with an annular recess formed by an annular spherical surface, then in such a lens the central optical zone is a round spherical surface with a radius of curvature R ₁ ranging from 7.21 mm to 10.21 mm and has a maximum diameter D _1max ranging from 3.0 mm to 4.0 mm, and the annular recess is formed by an annular spherical surface with a radius of curvature R ₂ ranging from 7.86 mm to 11.10 mm and has a maximum diameter D _2max ranging from 4.4 mm to 5, 6 mm, while the radius of curvature R _{2 of} the annular spherical surface is greater than the radius of curvature R _{1 of} the central optical zone.

The manufacture of lenses with radii of curvature R ₁ less than 7.21 mm or more than 10.21 mm is impractical, since at such radii the resulting hydraulic action will be insufficient to achieve the desired effect from the use of the claimed lens design.

The manufacture of lenses with maximum diameters D _1max less than 3.0 mm is not advisable, since with such diameters there is no sufficient redistribution of moisture in the sub-lens space and the central cells do not become sufficiently flat, and the manufacture of lenses with maximum diameters D _1max more than 4.0 mm is also not advisable, since with such diameters, the peripheral myopic defocus that forms in the eye is out of the patient's field of vision, which ultimately leads to the absence of the effect of slowing down the development of myopia.

The manufacture of lenses with radii of curvature R ₂ less than 7.86 mm or more than 11.10 mm is impractical, since at such radii the height of the annular tubercle formed on the cornea of the eye will be insufficient or excessive to create the desired myopic peripheral defocus.

The manufacture of lenses with maximum diameters D _2max less than 4.4 mm is impractical, since with such diameters an annular tubercle formed on the cornea of the eye will form close to the central optical axis of the patient's eye, which leads to a decrease in visual acuity, and the manufacture of lenses with maximum diameters D _2max more than 5.6 mm is also impractical, since with such diameters, the peripheral myopic defocus formed in the eye is out of the patient's field of vision, which leads to the absence of the effect of slowing down the development of myopia.

In the event that we manufacture a lens with an annular recess formed by an annular conical surface, then in such a lens-central optical zone is a round spherical surface with a radius of curvature R ₁ ranging from 7.21 mm to 10.21 mm and has a maximum diameter D _1max in the range from 3.0 mm to 4.0 mm, and the annular recess is formed by an annular conical surface and has a maximum diameter D _2max in the range from 4.4 mm to 5.6 mm, while the maximum angle α _max at the top of the annular conical surface lies in the range from 150° to 170°.

The manufacture of a lens with a maximum angle α _max at the top of the annular conical surface less than 150° or more than 170° is impractical, since at such angles the height of the annular tubercle formed on the cornea of the eye will be insufficient or excessive to create the desired myopic peripheral defocus.

The rationale for the other above limits in a lens with an annular recess formed by an annular conical surface is the same as the rationale for the limits for a lens with an annular recess formed by an annular spherical surface.

It is also possible to manufacture and use an orthokeratological myopia slowing down lens according to the invention, in which the annular recess is formed by an annular toric surface. In such a lens, the central optical zone is a round toric surface with a radius of curvature R _1m along the meridional section of the lens ranging from 7.21 mm to 10.21 mm and with a radius of curvature R _1s along the sagittal section of the lens ranging from 7.21 mm to 10 .21 mm and has a maximum diameter D _1max ranging from 3.0 mm to 4.0 mm. The annular recess is formed by an annular toric surface with a radius of curvature R _2m along the meridional section of the lens ranging from 7.86 mm to 11.10 mm and with a radius of curvature R _2s along the sagittal section of the lens ranging from 7.86 mm to 11.10 mm. In this case, the maximum diameter D _{2max of the} recess is in the range from 4.4 mm to 5.6 mm. The radii of curvature R _2m and R _2s of the annular toric surface are greater than the radii of curvature R _1m and R _1s of the central optical zone, respectively.

The rationale for the above limits in a lens with an annular recess formed by an annular toric surface is the same as the rationale for the limits for a lens with an annular recess formed by an annular spherical surface.

It would be expedient that the inventive orthokeratological lens have a maximum depth h _max of the annular recess, measured from a spherical or toric surface forming a central optical zone not exceeding 100 microns.

The manufacture of a lens with a maximum depth h _max of an annular recess of more than 100 μm leads to excessive myopic peripheral defocus, which reduces the visual acuity of the patient.

The choice of the type and specific above-mentioned geometric parameters of the proposed orthokeratological lens for a particular patient depends on the geometric and other parameters of his eye.

Variants of the proposed orthokeratology lens for slowing the development of myopia will be further described in more detail, while the following drawings will be used, in which:

Fig. 1 is a schematic axial section through an orthokeratology myopia slowing lens according to the invention, on an enlarged scale;

Fig. 2 is a schematic posterior view of an orthokeratology myopia retardation lens according to the invention, on an enlarged scale;

Fig. 3 is a partial schematic sectional view of an orthokeratology myopia retardation lens according to the invention, in which the annular recess is formed by an annular spherical surface, on an enlarged scale;

Fig. 4 is a partial schematic sectional view of an orthokeratology myopia retardation lens according to the invention, in which the annular recess is formed by an annular conical surface, on an enlarged scale;

Fig. 5 is a partial schematic meridional section of an orthokeratology myopia retardation lens according to the invention, in which the annular recess is formed by an annular toric surface, on an enlarged scale;

Fig. 6 is a partial schematic sagittal sectional view of an orthokeratology myopia retardation lens according to the invention, in which the annular recess is formed by an annular toric surface, on an enlarged scale;

and a set of tables in which:

Table No. 1 reflects the geometric parameters of the proposed orthokeratological lens, in which the annular recess is formed by an annular spherical surface;

Table No. 2 reflects the geometric parameters of the proposed orthokeratological lens, in which the annular recess is formed by an annular conical surface;

Table No. 3 reflects the geometric parameters of the proposed orthokeratological lens, in which the annular recess is formed by an annular toric surface.

Below, with reference to FIG. 1, Fig. 2 and FIG. 3, an example of our most commonly produced No. 1 orthokeratology lens is shown.

Such a lens contains a convex front surface 1 (Fig. 1) and a concave rear surface 2 facing, when using the lens, the patient's eye. The concave rear surface 2 contains a central optical zone 3 (Fig. 2) and an annular return zone 4 surrounding the central optical zone 3. An annular recess 5 is formed between the central optical zone 3 and the annular return zone 4, adjacent, on the one hand, to the central round optical zone 3 and, on the other hand, to the annular return zone 4. The annular return zone 4 smoothly passes into the annular support zone 6, which in turn smoothly passes into the annular edge zone 7. The central optical zone 3 (Fig. 3) is round spherical surface with a radius of curvature R ₁ equal to 7.85 mm, and has a maximum diameter D _1max equal to 3.8 mm. In this case, the annular recess 5 is formed by an annular spherical surface 8 with a radius of curvature R ₂ equal to 8.69 mm and has a maximum diameter D _2max equal to 5.4 mm. It should be noted that the radius of curvature R _{2 of} the annular spherical surface is greater than the radius of curvature R _{1 of} the central optical zone.

In this lens, the maximum depth h _max of the annular recess 5, measured from the spherical surface forming the central optical zone 3, is 65 μm.

The above lens was made for a patient with the following eye parameters:

- curvature of the cornea, equal to 45 diopters;

- eccentricity of the cornea of the patient's eye, equal to 0.5;

- correctable refraction of the eye, equal to - 1.0 diopters;

- pupil diameter under normal illumination, equal to 4.5 mm.

Table No. 1 below shows other options for manufacturing lenses No. 4-8, in which the annular recess is also formed by an annular spherical surface. These lenses No. 4-8 have the same design as the design of the above lens No. 1, but their geometric parameters are different, such as those shown in Table No. 1.

Below, with reference to FIG. 1, Fig. 2 and FIG. 4, an example of the claimed orthokeratological lens No. 2 for slowing the development of myopia is shown, in which the central optical zone is a round spherical surface and the annular recess is formed by an annular conical surface. Such a lens contains a convex front surface 1 (Fig. 1) and a concave rear surface 2 facing, when using the lens, the patient's eye. The concave rear surface 2 contains a central optical zone 3 (Fig. 2) and an annular return zone 4 surrounding the central optical zone 3. An annular recess 5 is formed between the central optical zone 3 and the annular return zone 4, adjacent, on the one hand, to the central round optical zone 3 and, on the other hand, to the annular return zone 4. The annular return zone 4 smoothly passes into the annular support zone 6, which in turn smoothly passes into the annular edge zone 7. As in the previous embodiment

lens, the central optical zone 3 of this lens is also a round spherical surface, but its radius of curvature R ₁ is 8.54 mm and the maximum diameter D _1max is 4.0 mm. In addition, unlike the lens of the previous example, the annular recess 5 (Fig. 4) is formed by an annular conical surface 9 and its maximum diameter D _2max is 5.2 mm. In this lens, the maximum depth h _max of the annular recess 5, measured from the spherical surface forming the central optical zone 3, is 68 μm. The maximum angle α _max at the top of the annular conical surface 9 is equal to 163°.

The above lens was made for a patient with the following eye parameters:

- curvature of the cornea, equal to 42.75 diopters;

- eccentricity of the cornea of the patient's eye, equal to 0.48;

- correctable refraction of the eye, equal to - 2.5 diopters;

- pupil diameter under normal illumination, equal to 5 mm.

Other options for manufacturing lenses No. 9-12, in which the annular recess is formed by an annular conical surface, has the same design as the design of the above-described lens No. 2, but their geometric parameters are different, such as shown in Table No. 2.

Below, with reference to FIG. 1, Fig. 2, Fig. 5 and FIG. 6, an example of our No. 3 myopia retardation orthokeratology lens made according to the invention, in which the annular recess is formed by an annular toric surface, is shown. In such a lens, the central optical zone 3 is a round toric surface with a radius of curvature R _1m along the meridional section of the lens, equal to 8.09 mm, and with a radius of curvature R _1s along the sagittal section of the lens, equal to 8.08 mm, and has a maximum diameter D _1max equal to 3.8 mm. The annular recess 5 is formed by an annular toric surface 10 with a radius of curvature R _2m along the meridional section of the lens equal to 9.29 mm, and with a radius of curvature R _2s along the sagittal section of the lens equal to 8.85 mm. The maximum diameter D _{2max of the} annular recess 5 is 5.4 mm. It should be noted that the radii of curvature R _2m and R _2s of the annular toric surface are larger than the radii of curvature R _1m and R _1s of the central optical zone 3, respectively.

In this lens, the maximum depth h _max of the annular recess 5, measured from the toric surface forming the central optical zone 3, is 60 μm.

The above lens was made for a patient with the following eye parameters:

- curvature of the cornea, equal to 43.5 / 44.5 diopters;

- eccentricity of the cornea of the patient's eye, equal to 0.55;

- correctable refraction of the eye, equal to sph - 1.0 diopters cyl - 1.0 diopters ax 180°;

- pupil diameter under normal illumination, equal to 5 mm.

Other options for manufacturing lenses No. 13-16, in which the annular recess is formed by an annular toric surface, has the same design as the design of the above-described lens No. 3, but their geometric parameters are different, such as are given in Table No. 3.

For the application of the inventive orthokeratological lens, the target patient, as a rule, is a child in the period of growth, the preferred age is from 8 years, i.e. the age at which progressive myopia is usually detected, before the age of 14, with a confirmed diagnosis of progressive myopia, which means that the patient's vision deteriorates over time.

At the same time, in the vast majority of cases of myopia progression, the cause of progression is excessive, in comparison with the norm, eye growth. It is possible to use the inventive lens for a patient at an older age, if the patient has adapted to the emerging myopic defocus on the periphery of the retina. This excludes patients with the following contraindications:

Absolute:

• acute inflammatory eye diseases, epitheliopathy;

• history of corneal diseases (keratitis, dystrophy, keratectasia);

• systemic connective tissue diseases;

• diabetes mellitus, hormone therapy;

• 3-4 severity of dry eye syndrome;

• the only seeing eye;

• anatomical defects of the eyelids.

Relative:

Temporary:

• seasonal allergies;

• taking drugs that reduce tear production.

Permanent:

• condition after refractive operations;

• 1-2 severity DES (dry eye syndrome), for example, symptoms are present with the use of SCL (soft contact lenses), but are reduced by wearing glasses;

• long-term wearing of GPL (gas-permeable lenses), hydrogel SCLs.

The next step is to determine the parameters of the patient's eye. At this stage, the following parameters are defined:

Corneal curvature (determined by the average value of corneal keratometry in diopters);

Corrected refraction of the eye - the required change in the refraction of the cornea;

Corneal eccentricity - flattening of the cornea from the center to the periphery;

Patient pupil diameter - pupil size in normal light;

The total corneal diameter is needed to calculate the diameter of the lens.

Based on the data obtained, the lens is calculated, including the geometric parameters of the rear surface of the lens, namely, the radius or radii of curvature of the central optical zone, the maximum diameter of the central optical zone, the radius or radii of curvature of the annular surface, which forms an annular recess on the rear surface of the lens, is determined, or the radius at the top of the annular conical surface forming the annular recess on the rear surface of the lens, the maximum diameter of the annular surface forming the annular recess, the overall diameter of the lens.

Then, according to the obtained geometric parameters, a lens is made from a biocompatible material with a high oxygen permeability (DK≥100) on high-precision lathes. The following materials can be used as a lens material: Roflufocon D, Roflufocon E, Tisilfocon A and their analogues.

The lens is given to the patient, while the quality of the fit of the lens on the eye, the location of the previously calculated zones are evaluated.

The patient uses the lens during sleep, that is, puts on the lens before going to bed at night and removes it after sleep. At the same time, the duration of sleep should be at least 8 and not more than 11 hours. During this time, the shape of the corneal epithelium changes, i.e. the central part becomes flatter by the amount required for vision correction, and on the periphery an annular tubercle is formed with a deliberately calculated shape and in a predetermined position. The shape and position of the annular tubercle is determined by the shape and position of the annular recess made on the back surface of the inventive lens.

During the day, the patient has high visual acuity in the central region of the visual field. At the same time, on the periphery of the retina, the tubercle formed after wearing the lens forms a myopic defocus, that is, a clear image of the surrounding objects is located not on the retina, but in the inner region of the patient's eye. The transfer of a peripheral image into the eye makes it possible to slow down the growth of the eye and, thereby, reduce the rate of progression of myopia, in other words, the task of slowing down the development of myopia in a patient is solved.

Claims (13)

1. Orthokeratology lens for slowing the development of myopia, containing convex front surface; and concave rear surface facing, when using the lens, to the patient's eye, and containing central optical zone; an annular return zone surrounding the central optical zone; and an annular recess adjacent, on the one hand, to the central circular optical zone and, on the other hand, to the annular return zone. 2. The lens according to claim 1, in which the central optical zone is a round spherical surface with a radius of curvature R ₁ ranging from 7.21 mm to 10.21 mm and has a maximum diameter D _1max ranging from 3.0 mm to 4, 0 mm, and the annular recess is formed by an annular spherical surface with a radius of curvature R ₂ ranging from 7.86 mm to 11.10 mm and has a maximum diameter D _2max ranging from 4.4 mm to 5.6 mm, while the radius of curvature R _{2 of} the annular spherical surface is greater than the radius of curvature R _{1 of} the central optical zone. 3. The lens according to claim 1, in which the central optical zone is a round spherical surface with a radius of curvature R ₁ ranging from 7.21 mm to 10.21 mm and has a maximum diameter D _1max ranging from 3.0 mm to 4, 0 mm, and the annular recess is formed by an annular conical surface and has a maximum diameter D _2max ranging from 4.4 mm to 5.6 mm, while the maximum angle α _max at the top of the annular conical surface lies in the range from 150° to 170°. 4. The lens according to claim 1, in which the central optical zone is a round toric surface with a radius of curvature R _1m along the meridional section of the lens ranging from 7.21 mm to 10.21 mm and a radius of curvature R _1s along the sagittal section of the lens ranging from 7.21 mm to 10.21 mm and has a maximum diameter D _1max ranging from 3.0 mm to 4.0 mm, and the annular recess is formed by an annular toric surface with a radius of curvature R _2m along the meridional section of the lens ranging from 7.86 mm to 11.10 mm and with a radius of curvature R _2s along the sagittal section of the lens ranging from 7.86 mm to 11.10 mm, and has a maximum diameter D _2max ranging from 4.4 mm to 5.6 mm, while the radii of curvature R _2m and R _2s of the annular toric surface is greater than the radii of curvature R _1m and R _1s of the central optical zone, respectively. 5. The lens according to any one of claims 2 or 3, wherein the maximum depth h _max of the annular recess, measured from the spherical surface forming the central optical zone, does not exceed 100 µm. 6. The lens according to claim 4, in which the maximum depth h _max of the annular recess, measured from the toric surface forming the central optical zone, does not exceed 100 μm.

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