Patent Application
20240027793
This relates to a lens system for controlling anisometropia and a method thereof and more particularly for configuring a lens system to affect the progression of myopia and controlling anisometropia in patients with at least one myopic or pre-myopic eye.
References considered to be relevant as background to the presently disclosed subject matter are listed below:
Acknowledgement of the above references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.
Anisometropia is a condition where the refractive error differs between the two eyes. The difference in the axial lengths of the eyes is considered to be the principal cause of anisometropia (the more myopic eyes being more elongated). Any refractive error difference between the two eyes is to the detriment of the patient, whereas even a small difference (e.g. 0.25D or 0.5D) can be considered a less severe case of anisometropia. Anisometropia is a phenomenon that has negative impacts on visual skills and development. The negative impacts may be as follows: improper binocular development and impaired stereopsis (the higher the anisometropia, the poorer the binocular function); amblyopia and strabismus (anisometropia is a major cause for the development of amblyopia and increasing degree of anisometropia is associated with higher risk of developing strabismus); aniseikonia (i.e. difference in the perceived size or shape of retinal images between eyes); possible spectacle intolerance for Single Vision (SV) and Progressive Addition Lenses (PAL) and accommodative instability. Therefore, it is recommended to start treatment as soon as possible and in every refractive difference between the two eyes. The prevalence of anisometropia increases from preschool ages to youth and is parallel with myopia progression. Currently, the only treatment for anisometropia is Ortho-K lenses as described for example in [5-8]. Ortho-K lenses are generally lenses configured to mechanically affect the curvature of the cornea. However, clinically there is a doubt if it is being used by Eye Care Professionals (ECP)s for treating anisometropia. There is currently no treatment or suggested solution for anisometropia which is based on the use of ophthalmic lenses, meaning spectacle lenses or contact lenses providing optical power for visual correction.
Anisometropia refers hereinafter to any difference in Spherical Equivalent Refraction (SER). The present invention provides a myopia control lens being configured for controlling anisometropia in patients with at least one myopic or pre-myopic eye. More specifically, the invention relates to at least one ophthalmic lens for spectacles or contact lens configured for controlling and/or treating anisometropia (prevention and minimization). The ophthalmic lens of the present invention may be used in any anisometropic cases where at least one of the eyes is myopic or pre-myopic, whether the refraction and prescription is spherical and/or astigmatic. The term “controlling anisometropia” refers hereinafter both to the prevention of progression of difference between prescriptions of the two eyes of a patient and to the minimization of existing difference between prescriptions of the two eyes of a patient. The invention enables to affect the progression of myopia differently for each eye and, as a result, to bring both eyes to substantially the same level/degree of myopia or to minimize the difference between the two prescriptions. This enables thereafter (i.e. when both eyes have attained the substantially same level of myopia) to use, if needed, similar left and right myopia control lenses or treatment to slow down the myopia progression in both eyes with the same rate.
Therefore, according to a broad aspect of the present invention, there is provided a lens system for an individual with anisometropia having a different prescription (Rx) of each eye. The lens system includes at least one lens unit having an optical property profile defining (1) a central optical zone having an optical correction according to the Rx of a corresponding eye and (2) a peripheral zone being configured to provide at least one myopia controlling parameter, being determined to affect myopia progression differently for each eye corresponding to a desired amount of anisometropia. The amount of anisometropia refers to the difference between both eyes' SER. The desired amount of anisometropia may be set to a certain value corresponding to the complete reduction of the anisometropia, or to a difference of 0.25D, 0.5D, 0.75D or above. As described above, the at least one lens unit includes at least one ophthalmic lens. The peripheral zone is configured to provide at least one myopia controlling parameter being determined to control anisometropia and bring both eyes to substantially the same degree of myopia. The at least one myopia controlling parameter may include any parameter configured to affect and control the myopia progression, by way of, for example, affecting retinal peripheral defocus, peripheral blur, chromatic aberrations, creating visual cues and reducing retinal image contrast.
Each myopia controlling parameter may be characterized by its myopia controlling power that may vary between 0 (no myopia controlling power, e.g., a regular single vision lens) to 1 (maximum possible myopia controlling power), depending on the specific implementation of the selected myopia controlling parameter. The myopia controlling power of a myopia controlling parameter may be measured in Diopters, blur level, number, size and density of visual cues or any combination thereof, depending on the selected myopia controlling parameter.
In some embodiments, the lens unit providing at least one myopia controlling parameter affecting retinal peripheral defocus is an ophthalmic lens including myopic peripheral defocus parameter. The myopic peripheral defocus parameter enables to maximize myopic defocus and/or minimize hyperopic defocus of rays coming from far objects towards the eye. The lens of the present invention may impose at the periphery as much myopic defocus as possible, by placing rays coming from far in front of the retina. The term “myopic peripheral defocus parameter” refers to an optical feature generating an optical image being formed in front of the peripheral retina, for example by additional peripheral power.
The additional peripheral power may be determined as a function of at least one of: amount of anisometropia, Rx of each eye, axial length of each eye, age of the individual, rate of myopia progression or rate of myopic changes. The rate of myopia progression may be reflected by the amount of change in SER and/or the amount of change in axial length of either the less myopic eye or the more myopic eye in a certain time frame (for example, annual change of SER of the less myopic eye relative to the contralateral eye). The rate of myopic changes may be reflected by the rate in which the SER and/or the axial length of a pre-myopic eye (either hyperopic or emmetropic) progresses towards a more myopic state in a certain time frame. The time frame is not limited and can define any suitable time period such as days, months or years. In a specific and non-limiting example, a higher level of anisometropia is to be provided with a stronger additional peripheral power compared to a less severe case of anisometropia. Additionally or alternatively, a high prescription is to be provided with a myopia control lens configured with a stronger additional peripheral power compared to a lower prescription. Additionally or alternatively, a higher rate of myopia progression, or rate of myopic changes is to be provided with a myopia control lens configured with a stronger additional peripheral power compared to a lower rate of progression. Additionally or alternatively, a high axial length is to be provided with a stronger additional peripheral power than a shorter axial length. Additionally or alternatively, a child is to be provided with a stronger additional peripheral power than older patients. The maximum possible strength of the additional peripheral power that can be configured in each case depends upon the selected myopia controlling parameter and the level of compliance of the patient to that myopia controlling parameter.
Typically, anisometropia relates to three different anisometropic cases:
Accordingly, the technique of the presently disclosed subject matter may be implemented correspondingly as follows:
These implementations minimize the difference between central refraction of both eyes, meaning minimizing the anisometropia. In other words, one of the lenses which is intended for use with that one of the left and right eyes in which the myopia is initially weaker or the hyperopia is higher, as compared to that of the other eye, is configured to affect the eye vision through the periphery of the lens allowing the natural or inhibited progress of myopia of that eye to bring it to the level of the other eye.
In some other embodiments, a pair of myopia control lenses for spectacles are provided, configured for differently affecting myopia development/progression based on the initial difference in the anisomyopic eyes of a patient (i.e. interocular difference of refractive power).
According to another broad aspect of the presently disclosed subject matter, there is provided a method for treating an individual with anisometropia. The method includes obtaining a prescription (Rx) for each eye; calculating an existing amount of anisometropia; determining a desired amount of anisometropia to be reached, wherein the desired amount of anisometropia is lower than the existing amount of anisometropia; configuring a central optical zone of at least one lens to have an optical correction according to the Rx of the corresponding eye and determining a myopia controlling parameter of a non-central position to affect a progression of a myopia differently for each eye corresponding to the desired amount of anisometropia; and configuring a peripheral zone with the myopia controlling parameter. In this connection, it should be noted that the method of the presently disclosed subject matter may be implemented by a preprogrammed processing unit or manually by any Eye Care Professional (ECP).
In some embodiments, determining the myopia controlling parameter of the non-central position includes determining at least one of a myopia controlling power of a myopic peripheral defocus parameter.
Determining the myopia controlling power of a myopic peripheral defocus parameter may include calculating the additional peripheral power as a function of at least one of: amount of anisometropia, Rx of each eye, axial length of each eye, age of the individual, rate of myopia progression or rate of myopic changes.
In some embodiments, the method further includes identifying the more myopic eye or less hyperopic eye as compared to the contralateral one.
In some embodiments, determining the myopia controlling parameter of the non-central position includes minimizing myopia progression of the more myopic eye or less hyperopic eye as compared to the contralateral one.
In some embodiments, the method further includes configuring at least one lens unit having the central optical zone and the determined myopia controlling parameter of a non-central position.
In some embodiments, the method further includes configuring at least one ophthalmic lens unit comprising at least one spectacle lens or at least one contact lens.
In some embodiments, the technique further includes configuring a second lens unit. The second lens unit may have a single vision optical property profile corresponding to a less myopic or more hyperopic eye as compared to the contralateral one.
In some embodiments, the technique further includes configuring a second lens unit having an optical property profile defining (1) a central optical zone having an optical correction according to the Rx of a corresponding eye and (2) a peripheral zone being configured to provide a myopia controlling parameter being configured to affect a progression of a myopia differently for each eye.
In some embodiments, determining the myopia controlling parameter of a first lens unit includes fitting a stronger additional peripheral power to a more myopic eye as compared to the contralateral one and configuring a second lens unit having a reduced additional peripheral power as compared to the contralateral one.
In some embodiments, the method further includes obtaining an age of an individual.
In some embodiments, the method further includes calculating the reduced additional peripheral power to the less myopic or more hyperopic eye compared to the additional peripheral power calculated for the more myopic or less hyperopic eye, according to at least one of an individual's age, axial length, Rx of the corresponding eye, rate of myopia progression or rate of myopic changes.
In some embodiments, the method further includes obtaining a second prescription (Rx) for each eye and after both eyes have a substantially same degree of myopia, configuring a central optical zone of each lens to have an optical correction according to the Rx of the corresponding eye and determining an optical property of a non-central position to affect and control the progression of a myopia similarly in both eyes.
According to another broad aspect of the presently disclosed subject matter, there is provided a processing unit for providing an individualized lens optical property profile. The processing unit includes a data input utility being configured and operable to receive a certain prescription (Rx) of an individual of each eye, a data analyzer being configured and operable to calculate an existing amount of anisometropia, determining a desired amount of anisometropia to be reached, wherein the desired amount of anisometropia is lower than the existing amount of anisometropia; configuring a central optical zone of at least one lens to have an optical correction according to the Rx of the corresponding eye and determining a myopia controlling parameter of a non-central position to affect a progression of the ametropia (according to prescriptions) differently for each eye corresponding to the desired amount of anisometropia; and configuring a peripheral zone with the myopia controlling parameter and a data output utility being configured and operable to provide a lens optical property profile defining a central optical zone having an optical correction according to the Rx of the corresponding eye and a peripheral zone with the myopia controlling parameter.
In some embodiments, the data analyzer is configured and operable to determine the myopia controlling parameter of the non-central position by determining at least one of a myopic peripheral defocus, peripheral blur, chromatic aberrations, creating visual cues or reducing retinal image contrast.
In some embodiments, the data analyzer is configured and operable to determine the myopia controlling power of the selected myopia controlling parameter.
In some embodiments the myopia controlling parameter is a myopic peripheral defocus parameter and determining the myopia controlling power includes determining the additional peripheral power.
In some embodiments, the data analyzer is configured and operable to determine the additional peripheral power by calculating the additional peripheral power as a function of at least one of: amount of anisometropia, Rx of each eye, axial length of each eye, age of the individual, rate of myopia progression or rate of myopic changes.
In some embodiments, the data analyzer is configured and operable to identify the more myopic eye or less hyperopic eye as compared to the contralateral one and to determine the myopia controlling parameter of the non-central position by minimizing myopia progression of the more myopic eye or less hyperopic eye as compared to the contralateral one.
In some embodiments, the data analyzer is configured and operable to configure at least one lens unit having the central optical zone and the determined myopia controlling parameter of a non-central position.
In some embodiments, the data analyzer is configured and operable to configure at least one lens unit comprising at least one spectacle lens or at least one contact lens.
In some embodiments, the data analyzer is configured and operable to configure a second lens unit.
In some embodiments, the data analyzer is configured and operable to configure a second lens unit having a single vision optical property profile corresponding to a less myopic or more hyperopic eye as compared to the contralateral one.
In some embodiments, the data analyzer is configured and operable to configure a second lens unit having an optical property profile defining (1) a central optical zone having an optical correction according to the Rx of a corresponding eye and (2) a peripheral zone being configured to provide a myopia controlling parameter being configured to affect a progression of a myopia differently for each eye.
In some embodiments, the data analyzer is configured and operable to determine the myopia controlling parameter of a first lens unit by fitting a stronger additional peripheral power to a more myopic eye as compared to the contralateral one and configuring the second lens unit to have a reduced additional peripheral power as compared to the contralateral one.
In some embodiments, the data input utility is configured and operable to receive an age of an individual.
In some embodiments, the data analyzer is configured and operable to determine the reduced additional peripheral power according to at least one of an amount of anisometropia, rate of myopia progression, rate of myopic changes, axial length of the corresponding eye, an individual's age and Rx of the corresponding eye.
In some embodiments, the data analyzer is adapted, after both eyes have a substantially same degree of myopia, to configure a central optical zone of each lens to have an optical correction according to the Rx of the corresponding eye and determine an optical property of a non-central position to affect and control the progression of myopia similarly in both eyes.
In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
Reference is made to
In some embodiments, lens system 10 further includes a second lens unit 10B. The second lens unit 10B may have a single vision optical property profile corresponding to a less myopic or more hyperopic eye as compared to the contralateral one. Alternatively, second lens unit 10B may have an optical property profile defining (1) a central optical zone having an optical correction according to the Rx of a corresponding eye referred to in the figure as region C2 and (2) a peripheral zone being configured to provide a myopia controlling parameter being determined to affect a progression of a myopia differently for each eye referred to in the figure as region P2.
Reference is made to
In some embodiments, data analyzer 206 is configured and operable to configure at least one lens unit having the central optical zone and the determined myopia controlling parameter of a non-central position. This may be implemented by determining the myopia controlling parameter of the non-central position and defining the myopia controlling power of the determined myopia controlling parameter. For example, data analyzer 206 is configured and operable to determine the myopia controlling parameter of the non-central position by minimizing myopia progression of the more myopic eye or less hyperopic eye as compared to the contralateral one. Alternatively, data analyzer 206 is configured and operable to determine the myopia controlling parameter of a first lens unit by fitting a stronger additional peripheral power to a more myopic eye as compared to the contralateral one and configuring the second lens unit to have a reduced additional peripheral power as compared to the contralateral one. Alternatively, data analyzer 206 is configured and operable to determine the reduced additional peripheral power according to at least one of an amount of anisometropia, rate of myopia progression, rate of myopic changes, axial length of the corresponding eye, an individual's age and Rx of the corresponding eye. In a specific and non-limiting example, in case of a relatively high rate of myopia progression of the less myopic eye, the additional peripheral power may be reduced but to a lesser extent than in a case of a moderate rate of myopia progression. After both eyes have a substantially same degree of myopia data analyzer 206 is adapted to configure a central optical zone of each lens to have an optical correction according to the Rx of the corresponding eye and determine an optical property of a non-central position to affect and control the progression of myopia similarly in both eyes.
The following Table 1 represents examples of a normalized power of myopia controlling parameter prescribed for the more myopic eye for different age groups:
In this connection, it should be understood that the values of the normalized power of myopia controlling parameter varies between 0 and 1, when 0 represents no myopia controlling power, e.g., a regular single vision lens and 1 represents the maximum possible myopia controlling power of the selected myopia controlling parameter. Moreover, the values above are empiric approximative values, representing values in the range of plus or minus 10 percent and should not be considered as absolute precise values. The maximum possible myopia controlling power of the lens is determined according to the specification of the selected myopia controlling parameter and compliance of the patient. The normalization of the values within the range may be linear, logarithmic, exponential, polynomial or power, depending on the nature of the selected myopia controlling parameter. The selection of the appropriate value is determined according to a plurality of parameters including the age of the patient, his initial prescription or the expected decrease in the development rate of the myopia. On one side, high values of the myopia controlling parameter induce some distortions or aberrations, increasing the blur perception and reducing the capacity of the patient to view therethrough. On the other side, low values of the myopia controlling parameter may not suffice to affect myopia progression. Therefore, the selection of the values of the myopia controlling parameter enables to control the personalized myopic progression of each specific patient including the desired amount of anisometropia and the development rate of the myopia to be reached. The different proposed theoretical values in this and the examples described below are not limiting the configuration of the lens for which a plurality of other parameters should be taken into consideration such as parameters typically related to the technique of production of the lens.
The following Table 2 represents examples of a normalized power of myopia controlling parameter prescribed for the two eyes for different age groups:
As described above, Table 2 illustrates one embodiment of the presently disclosed subject matter in which the myopia controlling power of the myopia controlling parameter of the contralateral less myopic eye is reduced as compared to the myopia controlling power provided to the more myopic eye.
As described above, in some embodiments, the additional peripheral power may be determined as a function of rate of myopia progression, or rate of myopic changes of the less myopic eye or the more myopic eye relative to the contralateral eye. The following Table 3 illustrates one embodiment of the presently disclosed subject matter in which the myopia controlling power of the myopia controlling parameter of the contralateral less myopic eye is reduced as compared to the myopia controlling power provided to the more myopic eye. In particular Table 3 represents examples of a normalized power of myopia controlling parameter prescribed for the two eyes for different annual progression rate of the less myopic eye. As illustrated in the table for a higher rate of myopia progression, the myopia control lens is configured with a stronger additional peripheral power compared to a lower rate of progression.
The following Table 4 represents examples of additional peripheral power of myopic peripheral defocus parameter prescribed for the more myopic eye for different age groups:
In this example of Table 4, the maximal power compliance is determined to be +4D. For example, at younger ages, the additional peripheral power should be stronger compared to the additional peripheral power given in older ages.
In this specific and non-limiting example, the less myopic (i.e. contralateral eye) can have a single vision lens with its prescription, until the anisometropia is reduced completely, or to 0.25D, 0.5D, 0.75D or 1.00D (the difference between both eyes prescriptions). Myopia control lenses may be then fitted to both eyes.
The following are few non-limiting examples of the lens configuration, i.e. the optical power distribution map of the lenses, as well as a relation between the eye vision (prescription) and the lens map, and examples of different maps for different eyes based on the values defined in Tables 1-3 above.
A six-year-old individual has a prescription in which the right eye has a refractive error of −0.25D and the left eye has a refractive error of −1.50D. Processing unit 200 calculates that the amount of anisometropia is 1.25D and determines that the desired amount of anisometropia should be minimized as much as possible. Processing unit 200 identifies that the less myopic eye is the right eye and configures the lens of the right eye to be a “standard lens” i.e. to have a single vision lens having a dioptric power of −0.25D and the lens of the left eye to have a central region having a dioptric power of −1.50D and a peripheral region with a myopic peripheral defocus parameter having an additional peripheral power of +3D. When the difference between the eyes is reduced, the lenses of both eyes may be configured as myopia control lenses with a peripheral region having an additional peripheral power of +3D.
For the same subject, with the same prescriptions, the lens of the right eye may be configured to be a “standard lens” i.e. to have a single vision lens having a dioptric power of −0.25D and the lens of the left eye is configured to have a central region having a dioptric power of −1.50D and a myopia controlling parameter of reducing retinal image contrast with peripheral contrast reduction of 50% relative to an image contrast viewed using the clear aperture of the lens. When the difference between the eyes is reduced, the lenses of both eyes may be configured as myopia control lenses with a peripheral contrast reduction of 50% relative to an image contrast viewed using the clear aperture of the lens for best controlling both eyes myopia.
In another specific and non-limiting example, in which the right eye has a refractive error of −5.00D and the left eye has a refractive error of −7.50D, processing unit 200 identifies that the less myopic eye is the right eye and configures the lens of the right eye to be a “standard lens” i.e. to have a single vision lens having a dioptric power of
−5.00D and the lens of the left eye may be configured to have a central region having a dioptric power of −7.50D and a peripheral region with a myopic peripheral defocus parameter having an additional peripheral power of +3D. It should be noted that in this example, the age is not taken into consideration since the amount of anisometropia as well as the value of the myopia is high. The additional peripheral power is determined to be the maximal value (e.g. +3D). This example may be given for any age. When the difference between the eyes is reduced, the lenses of both eyes may be configured as myopia control lenses with a peripheral region having an addition power of +3D.
For the same subject, with the same prescriptions, the lens of the right eye is configured to be a “standard lens” i.e. to have a single vision lens having a dioptric power of −5.00D and the lens of the left eye is configured to have a central region having a dioptric power of −7.50D and a myopia controlling parameter of reducing retinal image contrast with peripheral contrast reduction of 60% relative to an image contrast viewed using the clear aperture of the lens, due to the high prescriptions and anisometropia. When the difference between the eyes is reduced, the lenses of both eyes may be configured as myopia control lenses with a peripheral contrast reduction of 50% relative to an image contrast viewed using the clear aperture of the lens for best controlling both eyes myopia.
As described above, the second implementation of the technique of the presently disclosed subject matter is configuring one lens by fitting the strongest, or strong enough additional peripheral power to the more myopic eye and configuring the other lens by providing a myopia control lens with reduced additional peripheral power to the contralateral less myopic eye. This lower peripheral power may be adjusted according to the age and prescription of the less myopic eye of the patient and may be changed and adjusted at some stages of treatment, according to the myopia progression of each eye, rate of myopia progression or rate of myopic changes. When anisometropia is reduced completely, or to 0.25D, 0.5D, 0.75D or 1.00D (the difference between both eyes prescriptions), myopia control lenses with the same peripheral power or single vision lenses are then fitted to both eyes.
In one specific and non-limiting example, in which the right eye of a seven years old individual has a refractive error of −0.25D and the left eye has a refractive error of −1.50D, the lens of the right eye is configured to have a central region having a dioptric power of −0.25D and a peripheral region having an addition power of +1.5D for controlling its myopia, but in a weaker power compared to the more myopic eye and the lens of the left eye is configured to have a central region having a dioptric power of −1.50D and a peripheral region having an addition power of +2.5D. The additional power is given to prevent from the more myopic eye, higher progression of the myopia. When the difference between the eyes is reduced, the lenses of both eyes may be configured as myopia control lenses with a peripheral region having an addition power of +3D for best controlling both eyes myopia.
In a specific and non-limiting example, for the same subject, with the same prescription, if the rate of annual progression of myopia in the right eye is 1.00D, the lens of the right eye may be configured to have a central region having a dioptric power of −0.25D and a peripheral region having an addition power of +1.50D for controlling its myopia, and the lens of the left eye may be configured to have a central region having a dioptric power of −1.50D and a peripheral region having an addition power of +2.50D.
However, if the rate of annual progression of myopia in the right eye is 0.50D, the lens of the right eye may be configured to have a central region having a dioptric power of −0.25D and a peripheral region having an addition power of +1.00D for controlling its myopia, and the lens of the left eye may be configured to have a central region having a dioptric power of −1.50D and a peripheral region having an addition power of +2.25D. When the difference between the eyes is reduced, the lenses of both eyes may then be configured as myopia control lenses with a peripheral region having an addition power of +3D for optimizing the control of both eyes' myopia.
In another specific and non-limiting example, for the same subject, with the same prescription, the lens of the right eye may be configured to have a central region having a dioptric power of −0.25D and a myopia controlling parameter of reducing retinal image contrast with peripheral contrast reduction of 40% relative to an image contrast viewed using the clear aperture of the lens. The lens of the left eye may be configured to have a central region having a dioptric power of −1.50D and a myopia controlling parameter of reducing retinal image contrast with peripheral contrast reduction of 50% relative to an image contrast viewed using the clear aperture of the lens. When the difference between the eyes is reduced, the lenses of both eyes may be then configured as myopia control lenses with a peripheral contrast reduction of 50% relative to an image contrast viewed using the clear aperture of the lens for optimizing the control of both eyes' myopia.
In another specific and non-limiting example, in which the right eye has a refractive error of −4.5D and the left eye has a refractive error of −7.00D, the lens of the right eye is configured to have a central region having a dioptric power of −4.5D and a peripheral region having an addition power of +2D and the lens of the left eye is configured to have a central region having a dioptric power of −7.00D and a peripheral region having an addition power of +3D Also, in this example, the age is not taken into consideration since the amount of anisometropia as well as the value of the myopia is high. The additional peripheral power is determined to be the maximal value (e.g. +3D). This example may be given for any age.
When the difference between the eyes is reduced, but anisometropia still exists, to correctly treat the myopia in both eyes, the difference between the addition powers between the eyes may be reduced and therefore, the right eye can have a myopia control lens with additional peripheral power of +2.5D and the left eye can have myopia control lens with additional peripheral power of +3D.
When anisometropia is reduced completely, or to 0.25D, 0.5D, 0.75D or 1.00D (the difference between both eyes prescriptions), myopia control lenses can be configured with additional peripheral power of +3D to both eyes.
As described above, a third implementation of the technique of the presently disclosed subject matter is using this treatment for preventing the development of anisometropia by using it in early stages, when the child is still not a myope, but the peripheral refraction of the retina becomes hyperopic. Researchers found that children who became myopic have hyperopic peripheral refractive errors 1-2 years before the onset of myopia [9], and that the onset of myopia is well predicted by a refractive error <+0.75 D at 6 years, <+0.50 D at 7 to 8 years, <+0.25 D at 9 to 10 years, and less than plano at 11 years [10, 11]. At these cases, when there is a difference between refractions of both eyes, and at least one of them seems to become myopic or pre-myopic, the more myopic or less hyperopic eye may be configured to have a myopia control lens and the contralateral eye may have plano SV lens. Its prescription may be adjusted according to the development of prescriptions of both eyes. The myopia controlling parameter of the lens may be fitted according to the age of the child, the amount of anisometropia (difference in right/left eye prescription and/or axial length), the monocular prescriptions, axial length of each eye and/or the rate of myopic changes. The treatment is suitable for anisometropic children where the refractive error differs between the two eyes in 0.25D, 0.5D, 0.75D, 1.00D, 1.25D, 1.50D or more.
According to a broad aspect of the presently disclosed subject matter, there is provided a method of configuring a lens aimed at treating an anisometropic individual having a certain prescription (Rx). Reference is made to
In some embodiments, method 300 further includes configuring at least one lens unit having the central optical zone and the determined myopia controlling parameter of a non-central position in 314.
In some embodiments, method 300 includes the initial step of measuring a prescription (Rx) of at least one eye in 310. Optionally, method 300 may include storing all the data into a database in 316.
| Number | Date | Country | Kind |
|---|---|---|---|
| 279439 | Dec 2020 | IL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IL2021/051448 | 12/6/2021 | WO |
