System and method for determining an addition

Abstract

The disclosure relates to a system for determining an addition intended to be used for manufacturing a lens element for a potential wearer, the system comprising: a processor (60); and a memory (61) storing instructions that, when executed by the processor, cause the processor to: determine (52) an addition value, ADD, using a relation of the form ADD = EXP(ƒ), where ƒ is a linear function including at least one variable representing a characteristic of the potential wearer.

Description

SYSTEM AND METHOD FOR DETERMINING AN ADDITIONDOMAIN

[0001] The present invention relates to ophthalmic optics and more particularly to a system and a method for determining an addition, a system and a method for determining a lens element, and a computer program.BACKGROUND

[0002] In the field of ophthalmic optics, there is a constant need for determining an appropriate addition value in view of providing a satisfactory near-vision correction, particularly for presbyopic wearers. An accurate addition value enhances visual comfort, reduces eye strain, and improves satisfaction with lens performance.

[0003] One common approach used by eyecare professionals (ECPs) involves simplified methods such as the age-addition link, which correlates age with a corresponding addition value, and the so-called “clinical formulas”, typically expressed for example as ADD = 2.50 - 0.50 x Amax or ADD = 2.50 - 2 / 3 x Amax, where Amax represents the maximum accommodation measured via a subjective push-up method.

[0004] While these methods are quick and easy to apply, they often fail to account for the variability in individual visual characteristics, leading to suboptimal results for many wearers.

[0005] While effective in providing a rapid estimation of addition values, these techniques have known trade-offs, including reduced accuracy and an inability to fully personalize prescriptions based on specific wearer characteristics such as pupil size, ergonomic parameters, or detailed accommodative abilities.

[0006] More precise methods, such as conducting a near vision subjective refraction eye exam, are considered the gold standard but are often deemed too time-consuming for regular use in clinical practice.

[0007] To address these challenges, there is a growing need for an addition determination method that retains the speed and simplicity of current approaches with enhanced accuracy and / or enhanced personalization.SUMMARY

[0008] The invention is defined by the appended independent claims. Additional features and advantages of the concepts herein disclosed are set forth in the description which follows.

[0009] The present disclosure aims at improving the situation.

[0010] To this end, the present disclosure describes a system for determining an addition intended to be used for manufacturing a lens element for a potential wearer, the system comprising:a processor; anda memory storing instructions that, when executed by the processor, cause the processor to: determine an addition value, ADD, using a relation of the form ADD = EXP(f), where f is a linear function including at least one variable representing a characteristic of the potential wearer.

[0011] The memory may include various forms of storage, such as volatile memory (e.g., RAM) for temporary storage of processing data and non-volatile memory (e.g., ROM, flash memory, or solid-state drives) for storing the operational software and microstructure design templates. The memory is used to store the computer program comprising instructions for executing the described methods.

[0012] The computer program, which is stored on a computer -readable storage medium, comprises instructions that are accessible to the processor. When executed, these instructions enable the processor to perform the described methods. The computer -readable storage medium may include hard drives, solid-state drives, optical disks (e.g., CDs or DVDs), USB drives, or any other non-transitory storage medium capable of retaining the program. The program may be installed locally on the manufacturing device or system or accessed remotely via the communication interface.

[0013] The computer program enables the processor to execute the detailed steps of the method.

[0014] The present disclosure also describes a method for determining an addition value, ADD, using a relation of the form ADD = EXP(f),where f is a linear function including at least one variable representing a characteristic of the potential wearer.

[0015] Using a relation of the specified form allows predicting addition values with a much higher accuracy within ±0.25 diopters for more wearers than known methods using the so-called “clinical formulas” and “age-addition links”.

[0016] Further, unlike time-consuming subjective methods like near-vision examinations, using a relation of the specified form enables rapid and accurate predictions.

[0017] The present disclosure also describes a system for determining a lens element for a potential wearer, the system comprising:a processor; anda memory storing instructions that, when executed by the processor, cause the processor to: determine an addition value, ADD, according to any one of the preceding claim, and determine the lens element by selecting, generating, manufacturing or configuring the lens element based on the determined addition value.

[0018] The present disclosure also describes a method for determining a lens element for a potential wearer, the method comprising:determining an addition value, ADD, using a relation of the form ADD = EXP f), where f is a linear function including at least one variable representing a characteristic of the potential wearer, anddetermining the lens element by selecting, generating, manufacturing or configuring the lens element based on the determined addition value.

[0019] By improving the precision of the addition value, the likelihood of determining a lens element having an optimal configuration increases, minimizing discomfort or dissatisfaction among wearers.

[0020] The systems and methods described herein may, for instance, be implemented in computational tools for lens customization.

[0021] The present disclosure also describes a computer-readable storage medium, optionally a non-transitory computer-readable storage medium, having stored thereon a computer program comprising instructions which, when executed by a processor, cause the processor to perform any one of the methods hereby described.

[0022] The storage medium may include hard drives, solid-state drives, CDs, USB drives, etc. In this context, it is being used to refer to whatever medium is storing the computer program that runs the method.

[0023] The present disclosure also describes a computer program comprising instructions that are accessible to a processor and which, when executed by the processor, cause the processor to perform any one of the methods hereby described.

[0024] The systems and methods described in the present disclosure may furthermore comprise the following features, taken alone or in combination.

[0025] In an example, the at least one variable comprises an accommodative parameter, ACC, of the potential wearer.

[0026] Accommodative parameters provide a direct measure of remaining accommodation reserve, which reflects accommodation capabilities, improving prediction accuracy compared to methods based solely on age.

[0027] In an example, the accommodative parameter comprises an element of a list comprising:an objective assessment of accommodative capability,a subjective assessment of accommodative capability measured using a push-up method or a push-down method,an index derived from one or more of the preceding elements, anda linear combination of one or more of the preceding elements.

[0028] In an example, the instructions, when executed by the processor, further cause the processor to:determine the potential wearer as presbyopic based on applying a criterion taking into account at least one element of a list comprising :the accommodative parameter of the potential wearer,at least one ergonomic parameter,a comfortable accommodation value,an index derived from one or more of the preceding elements, anda linear combination of one or more of the preceding elements.

[0029] In an example, the at least one ergonomic parameter comprises a Harmon distance and the criterion is applied as following:ACC * (Harmon + 0.05m) < kwherein k is included between [0.3 ; 0.7],

[0030] In an example, the at least one ergonomic parameter comprises a Harmon distance, and the criterion is applied as following:Harmon + 0.05m < Aconfdwherein Aconfd is a comfortable accommodation at a working distance, d, andd is included between [25cm ; 100cm],

[0031] In an example, the at least one variable comprises an age, AGE, of the potential wearer.

[0032] In an example, the at least one variable comprises a pupil size, PUP, of the potential wearer.

[0033] Pupil size affects near-vision performance, enabling better addition customization.

[0034] In an example, f is defined as f = a * ACC + b * AGE + c * PUP + d, where: a is a fixed value greater than or equal to -1 and smaller than or equal to 0;b is a fixed value greater than or equal to 0 and smaller than or equal to 1;c is a fixed value greater than or equal to -1 and smaller than or equal to 1;d is a fixed value greater than or equal to -5 and smaller than or equal to 5; andat least one of a and b is non-zero.

[0035] Using the above formula for effectively combines ACC and AGE to determine the addition, which improves precision.

[0036] In an example, c is non-zero.

[0037] Using the above formula for / effectively combines ACC and PUP, which are multiple dimensions of visual performance, as well as AGE, to determine the addition, which further improves precision.

[0038] In an example, a, b, c and d are set up according to an element of a list comprising: an ergonomic parameter, anda light environment parameter.

[0039] Setting the coefficients a, b, c and d based on parameters that reflect real-world usage scenarios and / or real-world varying lighting conditions may improve practical utility.BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 depicts the statistical accuracy of an addition determination method in an exemplary embodiment in comparison to known addition determination methods.

[0041] Figure 2 depicts addition values of a group of individuals, as measured through eye exams, as a function of addition values of the individuals determined with an addition determination method in an exemplary embodiment.

[0042] Figure 3 depicts the statistical accuracy of addition determination methods in two distinct exemplary embodiments.

[0043] Figure 4 depicts addition values of a group of presbyopic individuals, as measured through eye exams, as a function of addition values of the presbyopic individuals determined with an addition determination method in an exemplary embodiment.

[0044] Figure 5 depicts a workflow of an addition determination method in an exemplary embodiment.

[0045] Figure 6 depicts a processing circuit in an exemplary embodiment.DETAILED DESCRIPTION

[0046] The present disclosure is focused on methods and systems for determining an addition, where the addition is intended to be used for determining (e.g. manufacturing, selecting, generating, controlling, etc.) a lens element for a potential wearer.

[0047] A lens element, in the context of the present disclosure, refers to an optical component. A lens element comprises at least one substrate and may include additional functional or structural components, such as layers, coatings, films, or microlenses. Examples of lens elements include, but are not limited to, optical lenses, ophthalmic lenses, wearable lenses, spectacle lenses, intraocular lenses, contact lenses, optical lenses of augmented reality (AR) or virtual reality (VR) headsets, and components thereof. Such components may include inserts, films, wafers, or other functional layers. The lens element may be piano or prescriptive, tinted or untinted, and may incorporate additional functions provided by coatings (e.g., anti -reflective, anti-scratch, or hydrophobic coatings). The lens element may be used independently or integrated into another optical system.

[0048] A lens element may provide optical correction by compensating for spherical, cylindrical, or prismatic refractive errors. Sphere refers to the optical power required to correct myopia or hyperopia. Cylinder refers to the correction of astigmatism, typically defined by its axis and magnitude. Prism refers to the displacement of the optical axis to address issues such as binocular vision misalignment. Additionally, the addition is a specific parameter associated with near-vision correction, particularly for presbyopia. The addition represents the dioptric difference between the far-vision correction and the near-vision correction provided by the lens element.

[0049] A lens element may be designed as a progressive addition lens (PAL), which provides a continuous progression of optical power from the far-vision zone to the near-vision zone. PALs are characterized by the following. A meridian is a central line of the lens where the optical progression occurs. A corridor is an area around the meridian where the addition progresses. A Far Vision point (or zone) is a point (or zone) on the lens optimized for viewing distant objects. A Near Vision point (or zone) is a point (or zone) on the lens optimized for viewing near objects. A progression length is a distance along the meridian from the far-vision point (or zone) to the near-vision point (or zone). The progression length impacts wearer comfort and adaptation to the lens.

[0050] A lens element comprises at least a first surface and a second surface. These surfaces are typically two opposite surfaces of the lens element. The surface designed to face the wearer’s eye under wearing conditions is referred to as the back surface, while the surfacedesigned to face the external scene or environment is referred to as the front surface. The at least one substrate of the lens element lies between these surfaces. The front and / or back surfaces may include specialized curvatures to provide the required refractive corrections. The front and / or back surfaces may also be aspherical or incorporate complex geometries to enhance optical performance. The front and / or back surfaces may include additional functionalities, such as anti -reflective coatings or tinting.

[0051] A lens element suitable for a wearer or potential wearer refers to a lens element designed to accommodate the visual needs of an individual based on their optical requirements. The suitability of a lens element depends on factors such as the wearer's refractive errors (if any), visual preferences, and physiological characteristics.

[0052] A wearer is an individual who utilizes a lens element for optical correction, visual enhancement, or other functional benefits. A potential wearer is an individual for whom a lens element may be selected, recommended, or prescribed based on their visual needs, whether identified through clinical assessment, personal preference, or computational analysis.

[0053] A wearer or potential wearer may have one or more of the following optical conditions. Emmetropia is a condition where the eye does not require refractive correction because it can focus light correctly on the retina. Myopia or nearsightedness is a refractive error in which distant objects appear blurred due to excessive convergence of light before reaching the retina. Hyperopia or farsightedness is a refractive error in which near objects appear blurred due to insufficient convergence of light on the retina. Astigmatism is a condition where irregular corneal or lens curvature results in blurred or distorted vision at all distances.

[0054] Presbyopia is an age-related eye condition characterized by the gradual loss of the eye's accommodation, typically manifesting as difficulty focusing on near objects.

[0055] In the context of presbyopia, a lens element suitable for the wearer is generally configured to provide additional near-vision correction, often through an addition power that compensates for reduced accommodation.

[0056] A lens element may be specifically designed for presbyopic wearers by incorporating:progressive addition lenses (PALs), which provide a gradual transition from distance to near vision, and / orbifocal or multifocal lenses, which include discrete zones for different focal distances, and / orenhanced single vision lenses, which provide a minor near-vision boost for emerging presbyopia.

[0057] Additionally, a lens element may integrate functional adaptations to improve wearer experience, such as blue-light filtering, contrast enhancement, or digital strain reduction.

[0058] Accommodation refers to the ability of the eye to adjust its shape to focus on objects at different distances. This process is mediated by the ciliary muscles and results in changes in the eye’s curvature. Accommodation may be quantified by an accommodative parameter, usually expressed in diopters.

[0059] The accommodative parameter may be categorized as following.

[0060] The maximum accommodation (or amplitude of accommodation) is the maximum change in optical power the eye can achieve when focusing from a far point to a near point. The maximum accommodation typically decreases with age due to the progressive stiffening of the crystalline lens and reduced efficiency of the ciliary muscles. In young individuals (e.g., below 10 years), the amplitude of accommodation can be as high as 15 D or more. By the age of 40-45, the amplitude of accommodation typically falls below 3 D, leading to noticeable presbyopic symptoms. Around the age of 60, accommodation is nearly absent, making near-vision correction essential

[0061] The comfortable accommodation (or functional accommodation range) is the range of accommodation that allows a wearer to maintain clear vision comfortably over extended periods. The comfortable accommodation is generally lower than the maximum accommodation because sustained accommodation beyond a certain threshold leads to visual fatigue or discomfort.

[0062] An accommodative parameter may be assessed by an objective method and / or by a subjective method.

[0063] An accommodative parameter may be assessed by a monocular method and / or by a binocular method.

[0064] Objective methods use instruments, such as autorefractors, aberrometers, or photorefraction, to measure accommodation without reliance on subjective input from the wearer. Such methods provide precise and repeatable results for clinical assessment.

[0065] Subjective methods rely on the wearer’s response during visual tasks. In the push-up method, the maximum accommodative amplitude is determined by moving an object closer to the eye until blur occurs. In the push-down method, the accommodation is assessed bymoving an object away from the eye until it becomes clear. In the minus-lens method, lenses of increasing negative power are introduced to stimulate accommodation.

[0066] The addition power of a presbyopic lens element may for instance be determined based on the wearer's remaining accommodative ability and preferred near-working distance. A lower remaining accommodation necessitates a higher addition power.

[0067] An accommodative parameter may be assessed by a measure of an accommodative flexibility, for example a binocular and / or monocular (dominant eye) flipper lens tests.

[0068] An aspect of the proposed technique relates to a system for determining an addition intended to be used for determining a lens element for a wearer or potential wearer.

[0069] The term “determining” in the context of a system for determining a lens element for a wearer or potential wearer can encompass a wide range of actions, depending on the specific use case and technological implementation.

[0070] For instance, determining a lens element may refer to selecting or recommending an appropriate lens element from a database, a catalog, or a predefined set of lens elements, where the selection or recommendation is based on the determined addition value. The selection may involve comparing parameters such as addition value, optical power, design type, and / or coatings to identify a lens element suitable for the potential wearer.

[0071] Determining a lens element may also refer to defining one or more specifications for manufacturing a lens element, where the determined addition value influences parameters such as the lens element’s optical profile, surface curvatures, thickness, material, or coating properties. The determination may include generating manufacturing instructions for a production system, such as a freeform surfacing system, a molding system, or a coating deposition system, where the determined addition value is incorporated into the specifications to ensure appropriate near-vision correction.

[0072] Determining a lens element may further refer to generating an optical design of the lens element, where the determined addition value is used to compute a spatially varying optical power distribution, define a progressive addition profile, or optimize an aberration-corrected geometry. The determination may involve simulating optical performance based on wearer parameters and optimizing the lens design to achieve a targeted balance between vision clarity, wearer adaptation, and visual comfort.

[0073] Determining a lens element may also refer to dynamically controlling an active or adaptive lens element, where the determined addition value is used as an input for adjusting one or more optical properties of the lens element. Such optical properties may include focal power, optical zone transitions, or light transmission characteristics. The active or adaptivelens element may comprise an electrically tunable lens, a liquid crystal -based adjustable lens, an electrochromic lens, or a lens incorporating other modifiable optical properties. The determination may involve adjusting the lens element based on detected conditions such as ambient lighting, the wearer’s gaze direction, accommodation response, or biometric inputs.

[0074] Determining a lens element may further refer to configuring the manufacturing process of a lens element to incorporate the determined addition value as part of a customized or semi-customized fabrication workflow. The determination may involve selecting or modifying base lens blanks, applying digital surfacing corrections, or controlling the application of functional coatings to adapt the lens element to the wearer’s visual requirements.

[0075] Determining a lens element may also refer to defining a computational model for an adaptive lens system, where the determined addition value serves as a parameter for an electronic or software-driven control system. The determination may involve generating adjustment rules for modulating the lens power dynamically, defining thresholds for transition between optical states, or integrating the addition value into an automated adjustment process that considers biometric feedback or environmental conditions.

[0076] Determining a lens element may additionally refer to coordinating the interaction between a lens element and an external control system that relies on the determined addition value. For instance, the determination may involve linking the addition value to an augmented reality or virtual reality system, a head-up display, or a vision-enhancing system, where the optical properties of the lens element are modified or adjusted based on external system inputs.

[0077] The system comprises:a processor; anda memory storing instructions that, when executed by the processor, cause the processor to: determine an addition value, ADD, using a relation of the form ADD = EXP( f ), where f is a linear function including at least one variable representing a characteristic of the wearer or potential wearer.

[0078] The determined addition value may be used to define or complete a prescription for the wearer or potential wearer by specifying an addition value in combination with spherical, cylindrical, and / or prismatic correction parameters. The determined addition value may be used to update an existing prescription by adjusting or supplementing a previously prescribed addition value based on newly determined wearer characteristics.

[0079] A characteristic of the wearer or potential wearer refers to a measurable or quantifiable attribute of the individual that influences the determination of the addition value, ADD.

[0080] Characteristics of the wearer or potential wearer can include, but are not limited to: the accommodative parameter, ACC, which as defined above is an estimate of the wearer’s or potential wearer’s accommodative capability,the age of the wearer or potential wearer, AGE, which is often inversely related to accommodative ability,the pupil size, PUP, which is the diameter of the pupil of an eye of the wearer or potential wearer under specific lighting conditions, which affects visual performance,light environment parameters such as luminance, contrast, or glare in the wearer’s or potential wearer’s environment,ergonomic parameters, which are factors related to the physical setup of the wearer’s or potential wearer’s typical visual tasks.

[0081] A light environment parameter assesses the lighting conditions in which the wearer typically performs visual tasks. Light environment parameters can influence pupil size, contrast sensitivity, glare perception, and overall visual comfort. The light environment parameter may comprise, for instance, one or more of the following. Luminance is a measure of the brightness of the surrounding environment, which affects pupil response and contrast perception. Luminance can be measured in lux and may vary between outdoor daylight, indoor artificial lighting, and dimly lit environments. Contrast levels are the ratio of light intensity between different areas of the visual field. Low contrast can make near-vision tasks more demanding, particularly for presbyopic wearers. Glare susceptibility is a parameter assessing the impact of excessive or disruptive light sources, such as reflections, strong sunlight, or artificial lighting. Glare can cause discomfort and visual fatigue, influencing the preferred optical characteristics of a lens element. Chromatic lighting conditions represent the spectral composition of the ambient light, including warm or cool light sources. Certain lighting conditions can affect visual performance, contrast perception, and adaptation to different lens tints or coatings. Temporal variations in lighting are fluctuations in lighting conditions over time, such as the transition from bright daylight to dim indoor environments. Wearers who frequently switch between such conditions may benefit from lenses with adaptive transmission properties. Preferred lighting conditions are subjective or learned preferences for specific lighting environments, such as a preference for high-luminance environments or avoidance of blue-light exposure. A light environment parameter maycorrespond to any one of the above elements or to a light environment index being a combination, for instance a weighted combination, of a plurality of the above elements.

[0082] An ergonomic parameter assesses visual ergonomics of the wearer or potential wearer. The ergonomic parameter may comprise, for instance, one or more of the following: a working distance, a Harmon distance, a postural parameter, or an index combining a plurality of the above elements. The working distance is the distance between the wearer’s eyes and the object being viewed. The Harmon distance is the typical viewing distance, approximately the length from the elbow to the middle knuckle of the dominant hand, used as a baseline for comfortable reading or near work. A postural parameter is a parameter related to the wearer’s head, neck, or body posture during visual tasks. This may include tilt angles of the head, shoulder alignment, or habitual viewing positions that affect the angle of gaze and visual strain. A head tilt angle indicates the inclination of the wearer’s head when engaging in near-vision tasks. A gaze direction parameter indicates a typical downward gaze when engaging in near-vision activities. A preferred reading zone is a preferred region within a lens where the wearer naturally directs their gaze for near-vision tasks. An ergonomic parameter may correspond to any one of the above elements or to an ergonomic index being a combination, for instance a weighted combination, of a plurality of the above elements.

[0083] A linear function is a mathematical expression of the form f = a x + — I- anxn+ d, where n is an integer,are variables, a1, ..., anare coefficients and d is a constant. In other words, a linear function f is a linear combination of the variables x , xn. In the context of the addition determination, the variables xlt... , xnrepresent characteristics of the potential wearer, and their respective coefficients a1, ..., anweight their contribution to the function f.

[0084] The coefficients a1, ... , anand the constant d may be set up according to one or more parameters of the wearer or potential wearer and / or of an environment of the wearer or potential wearer, for instance one or more ergonomic parameters as defined herein, and / or one or more light environment parameters as defined herein.

[0085] A variable representing a characteristic of the potential wearer serves as a mathematical abstraction of one or more measurable attributes, such as ACC, AGE, or PUP. It captures the characteristic in a numerical format for computational analysis.

[0086] In an example, at least one variable of f comprises an accommodative parameter, ACC, of the wearer or potential wearer, wherein the accommodative parameter comprises an element of a list comprising: an objective assessment of accommodative capability, a subjective assessment of accommodative capability measured using a push-up method or apush-down method, an index derived from one or more of the preceding elements, and a linear combination of one or more of the preceding elements.

[0087] An index refers to a value computed from one or more measurable parameters using a predefined formula. For example, an accommodation index may be defined as a weighted average or scaled representation of the wearer’s accommodative ability, combining for instance objective and subjective measurements.

[0088] In an example, f comprises at least one variable among ACC, AGE and PUP.

[0089] For instance, f may be defined as f = a * ACC + b * AGE + d, where:a is a fixed value greater than or equal to -1 and smaller than or equal to 0;b is a fixed value greater than or equal to 0 and smaller than or equal to 1;d is a fixed value greater than or equal to -5 and smaller than or equal to 5; andat least one of a and b is non-zero.

[0090] In this example, f comprises at least one variable among ACC and AGE and does not comprise PUP as a variable.

[0091] In a variant of this example, both a and b are non-zero, therefore f comprises: ACC as a first variable,AGE as a second variable, andf does not comprise PUP as an additional (third) variable

[0092] In an example, f is defined as f = a * ACC + b * AGE + c * PUP + d, where: a is a fixed value greater than or equal to -1 and smaller than or equal to 0;b is a fixed value greater than or equal to 0 and smaller than or equal to 1;c is a fixed value greater than or equal to -1 and smaller than or equal to 1;d is a fixed value greater than or equal to -5 and smaller than or equal to 5;at least one of a and b is non-zero, and c is non-zero.

[0093] In this example, f comprises at least one variable among ACC and AGE, and f further comprises PUP as an additional variable.

[0094] In a variant of this example, both a and b are non-zero, therefore f comprises: ACC as a first variable,AGE as a second variable, andPUP as a third variable.

[0095] Of course, in further variants of the above examples, f may further include additional variables in addition to ACC, AGE and / or PUP.

[0096] The instructions, when executed by the processor, may cause the processor to first determine whether the wearer or potential wearer is presbyopic or non-presbyopic. Based onthis determination, the processor may be configured to determine:an addition value according to the prescribed formula ADD = EXP(f) if the wearer or potential wearer is determined as presbyopic, andan addition value of zero if the wearer or potential wearer is determined as non-presbyopic.

[0097] Alternatively, based on this determination, the processor may be configured to refrain from determining any addition if the wearer or potential wearer is non-presbyopic.

[0098] Such determination is based on applying a criterion taking into account one or more of the following:an accommodative parameter of the wearer or potential wearer,an ergonomic parameter of the wearer or potential wearer,an index derived from one or more of the preceding elements,a linear combination of one or more of the preceding elements.

[0099] The application of the criterion may involve comparing an ergonomic criterion combining the wearer or potential wearer’s accommodation ability (ACC) with their typical near-vision viewing distance (e.g. their Harmon distance plus an offset).

[0100] In an example, an ergonomic parameter may comprise a Harmon distance in meter and the criterion is applied as following: - - - - > k wherein k is comprised ° ACC*(Harmon +0.05)between 0.3 and 0.7 and preferentially equal to 0.51.

[0101] In this example, the application of the criterion evaluates whether the wearer can achieve accommodation at ergonomic distances.

[0102] In a numerical example:the accommodation parameter, ACC, is a subjective assessment of accommodative capability measured using a push-down method and equal to 2.5D when expressed in diopters, which corresponds to 0.40 m when expressed in meters, meaning that the wearer can accommodate up to 40 cm,the Harmon distance, Harmon is equal to 0.35m, andk is chosen equal to 0.5.

[0103] Since 1 / ACC * (Harmon + 0.05m) = 1 / (2.5 * (0.35 + 0.05)) = 1.0 is superior to k = 0.51, the criterion is satisfied in this case. This means that the wearer might need additional near-vision correction and may therefore be classified as presbyopic by application of the criterion.

[0104] Instead of using a fixed Harmon distance, one could compare ACC to a dynamically adjusted working distance based on user behavior.

[0105] The application of the criterion may involve comparing an ergonomic criterion representing the comfortable accommodation limit (Aconfd) of the wearer or potential wearer with their typical near-vision viewing distance (e.g. their Harmon distance plus an offset).

[0106] In an example, an ergonomic parameter may comprise a Harmon distance in meter, and the criterion is applied as following: l / (Harmon+0.05) > Aconfa wherein Aconfa is a comfortable accommodation at a working distance, d, and d is included between 0.25m and 1.00m and preferentially equal to 0.40m.

[0107] In this example, the application of the criterion evaluates whether the wearer can sustain accommodation at ergonomic distances without discomfort.

[0108] In a numerical example:the Harmon distance, Harmon is equal to 0.35m,the working distance, d is equal to 0.40m,the maximum accommodation, is Amax = 2D when expressed in diopters, which corresponds to 0.5 m when expressed in meters, meaning that the wearer can accommodate up to 50 cm, andthe comfortable accommodation at the working distance, Aconfa is calculated as a function of Amax, for instance as being two thirds of Amax when expressed in diopters or 4 / 3D, which corresponds to 0.75 m when expressed in meters, meaning that the wearer can comfortably accommodate up to 75 cm.

[0109] Since l / (Harmon+0.05) is superior to Aconfa, the criterion is satisfied in this case. This means that the wearer might need additional near-vision correction and may therefore be classified as presbyopic by application of the criterion.

[0110] An experimental example has been conducted to compare different methods for determining an addition value ADD) for near vision correction. The comparison involves a group of 92 individuals, each of whom has key vision parameters measured. The group of 92 individuals comprises presbyopes and non-presbyopes.[OHl] The goal of the experimental example is to evaluate the accuracy of different addition determination methods against a reference addition, obtained through a near vision subjective refraction eye exam, which serves as the ground truth for comparison.

[0112] For each individual considered in the experimental example, the following parameters are obtained:the reference addition of the individual,the age AGE of the individual,the maximum accommodation of the individual Amax, measured using a push-up method, the maximum accommodation of the individual A'max, measured using a push-down method, used as an example of accommodation parameter ACC of the individual, the comfortable accommodation Aconfd of the individual at a distance d equal to 40 cm, the pupil size PUP of the individual, measured in binocular conditions at the punctum remotum, andthe Harmon distance of the individual, used as an example of an ergonomic parameter of the individual.

[0113] For each individual, the addition is recomputed using three different methods: an empirical age-addition link commonly used in clinical practice,the clinical formula ADD = 2.50 — 0.50 * Amax, anda relation of the form ADD = EXP ( ), where f is a linear function including A’max and AGE as variables, with coefficients fitted by regression analysis based on the reference addition values of the 92 individuals.

[0114] Specifically, with the group of individuals considered, the resulting relation, noted [Relation 1], is ADD = EXP(-0.4524 * A’max + 0.0577 * AGE - 1.5744).

[0115] For each individual and each addition recomputation method, the absolute difference between the reference addition value and the recomputed addition is determined. Based on this difference, individuals are categorized into four groups:Group 1: individuals for whom the absolute difference is smaller than or equal to 0.25D (highly accurate prediction),Group 2: individuals for whom the absolute difference is greater than 0.25D but smaller than or equal to 0.50D (acceptable clinical accuracy),Group 3 : individuals for whom the absolute difference is greater than 0.50D but smaller than or equal to 0.75D (moderate error), andGroup 4: individuals for whom the absolute difference is greater than 0.75D (significant error).

[0116] Figure 1 presents the distribution of individuals across these four groups for the three tested methods: empirical age-addition link 12, clinical formula 11 and the proposed exponential formula 10.

[0117] As illustrated in Figure 1, the relation of the form ADD = EXP(f) (in this example, [Relation 1], allows correctly predicting the addition value within 0.25D in 81.2% of cases. In contrast, the clinical formula achieves this accuracy in 65.9% of cases, while the ageaddition link method achieves it in 54.1% of cases.

[0118] In other words, the proposed technique enables the prediction of an addition value within 0.25D of the reference value for an additional 15% of the population compared to the clinical formula and for an additional 27% of the population compared to the age-addition link method.

[0119] These results demonstrate that the combination of age and an accommodative parameter obtained by a push-down accommodation measurement with an exponential model using optimized coefficients provides a significantly higher accuracy in determining addition values compared to conventional approaches.

[0120] Figure 2 plots, for each of the 92 individuals, the reference addition in ordinate versus the addition recomputed by applying [Relation 1] in abscissa. The hollow dots 20 represent presbyopic individuals having a reference addition greater than 0.50D and the solid dots 21 represent non-presbyopic individuals having a reference addition smaller than or equal to 0.50D.

[0121] In a distinct approach, the 92 individuals are first classified into two groups:a group of presbyopes, anda group of non-presbyopes.

[0122] To classify the individuals, two different criteria are tested.

[0123] Applying the first criterion Amax * Harmon (m) + 0.05) < k results in correctly classifying 84 individuals out of 92.

[0124] Applying the second criterion Harmon (m) + 0.05 < Aconfd results in correctly classifying 90 individuals out of 92.

[0125] The addition of each individual classified as presbyope by applying the second criterion is recomputed using a relation of the form ADD = EXP(f), where f is a linear function including A'max, AGE and PUP as variables, with coefficients fitted by regression analysis based on the reference addition values of the individuals classified as presbyopes among the 92 individuals.

[0126] Specifically, in this group, the resulting relation, noted [Relation 2], is ADD = EXP(— 0.2143 * A’ max + 0.0228 * AGE - 0.1971 * PUP + 0.3885).

[0127] For each individual classified as presbyope, the addition value is determined using two different relations: [Relation 1] which is the original exponential relation fitted to the full dataset and [Relation 2], which is the exponential relation fitted exclusively on presbyopes after classification.

[0128] For each presbyope and each addition determination method ([Relation 1] and [Relation 2]), the absolute difference between the reference addition value and the recomputed addition value is calculated.

[0129] Based on this difference, individuals are categorized into four groups:Group 1: individuals for whom the absolute difference is smaller than or equal to 0.25D (highly accurate prediction),Group 2: individuals for whom the absolute difference is greater than 0.25D but smaller than or equal to 0.50D (acceptable clinical accuracy),Group 3 : individuals for whom the absolute difference is greater than 0.50D but smaller than or equal to 0.75D (moderate error), andGroup 4: individuals for whom the absolute difference is greater than 0.75D (significant error).

[0130] Figure 3 presents the distributions of presbyopes across these four groups, respectively when applying [Relation 1] 30 and when applying [Relation 2] 31. With [Relation 1], 70% of presbyopes fall into Group 1 (absolute difference < 0.25D) and the fourth group (absolute difference > 0.75D) is empty (i.e., no extreme errors). With [Relation 2], 90% of presbyopes fall into Group 1 (absolute difference < 0.25D), demonstrating an even higher accuracy, and both the third and fourth groups are empty (i.e., no errors greater than 0.50D). These results indicate that taking into account an additional parameter distinct from ACC and AGE (in this example PUP) and fitting the coefficients specifically on presbyopic individuals (as in [Relation 2]) improves accuracy, leading to a higher proportion of correct predictions within 0.25D and eliminating larger errors.

[0131] Figure 4 plots 40, for each of the presbyopic individuals, the reference addition in abscissa versus the addition recomputed by applying [Relation 2] in ordinate.

[0132] Figure 5 depicts a general workflow of a method as described herein, for determining an addition intended to be used for determining a lens element for an individual (e.g. a wearer or a potential wearer).

[0133] The method comprises, at least:obtaining 50 at least one characteristic of the individual, anddetermining 52 an addition value, ADD, using a relation of the form ADD = EXP (J), where f is a linear function including at least one variable representing the at least one obtained characteristic.

[0134] For instance, the at least one characteristic of the individual may comprise an accommodative parameter of the individual, at least one ergonomic parameter of the individual, and / or a comfortable accommodation value of the individual.

[0135] For instance, the method may further comprise determining 51 the individual as presbyopic based on applying a criterion taking into account the accommodative parameter of the individual, the at least one ergonomic parameter of the individual, and / or the comfortable accommodation value of the individual.

[0136] The method may further comprise determining 54 a lens element for the individual based on the determined addition value.

[0137] The method may further comprise generating 53 and / or transmitting instructions in view of determining 54 a lens element for the individual.

[0138] Figure 6 depicts a processing circuit adapted to implement the above method. The processing circuit comprises a processing unit 60 and a memory 61 operably connected to the processing unit and storing instructions that, when executed by the processor, cause the processor to, at least, determine the addition value of the individual, and, optionally, to determine the lens element for the individual based on the determined addition value.

[0139] Determining the lens element may comprise for instance:selecting the lens element among a set of lens elements,determining at least part of an optical design of the lens element,generating instructions to be used for manufacturing the lens element, and / or generating instructions to be used for configuring at least a dioptric function of the lens element.

[0140] The processing circuit may further comprise a communication interface 62 configured for instance to receive the at least one characteristic of the individual and / or to transmit the generated instructions.

[0141] This general description is intended to present an exemplary implementation of the invention. Variations, modifications, and alternatives may be apparent to those skilled in the art and can be made without departing from the scope of the invention. The specific configuration of components and the manner in which they interact are merely illustrative, and alternative configurations and interactions are within the scope of the appended claims.

Claims

Claims

1. A system for determining an addition intended to be used for manufacturing a lens element for a potential wearer, the system comprising:a processor (60); anda memory (61) storing instructions that, when executed by the processor, cause the processor to:determine (52) an addition value, ADD, using a relation of the form ADD = EXP (J), where f is a linear function including at least one variable representing a characteristic of the potential wearer.

2. The system of claim 1, wherein the at least one variable comprises an accommodative parameter, ACC, of the potential wearer.

3. The system of claim 2, wherein the accommodative parameter comprises an element of a list comprising:an objective assessment of accommodative capability,a subjective assessment of accommodative capability measured using a push-up method or a push-down method,an index derived from one or more of the preceding elements, anda linear combination of one or more of the preceding elements.

4. The system of claim 2 or 3, wherein the instructions, when executed by the processor, further cause the processor to:determine (51) the potential wearer as presbyopic based on applying a criterion taking into account at least one element of a list comprising :the accommodative parameter of the potential wearer,at least one ergonomic parameter,a comfortable accommodation value,an index derived from one or more of the preceding elements, anda linear combination of one or more of the preceding elements.

5. The system according to claim 4, wherein the at least one ergonomic parameter comprises a Harmon distance and the criterion is applied as following:— ACC*( ;H —armo -n +0.05m ?) >kwherein k is included between [0.3 ; 0.7]wherein when the criterion is satisfied, the potential wearer is presbyopic.

6. The system according to claim 4, wherein the at least one ergonomic parameter comprises a Harmon distance, and the criterion is applied as following: l / (Harmon+0.05m) > Aconfddis included between [25cm ; 100cm],wherein when the criterion is satisfied, the potential wearer is presbyopic.

7. The system of any one of the preceding claims, wherein the at least one variable comprises an age, AGE, of the potential wearer.

8. The system of any one of the preceding claims, where the at least one variable comprises a pupil size, PUP, of the potential wearer.

9. The system of any one of the preceding claims, wherein f is defined as f = a * ACC + b * AGE + c * PUP + d, where:a is a fixed value greater than or equal to -1 and smaller than or equal to 0;b is a fixed value greater than or equal to 0 and smaller than or equal to 1;c is a fixed value greater than or equal to -1 and smaller than or equal to 1;d is a fixed value greater than or equal to -5 and smaller than or equal to 5; andat least one of a and b is non-zero.

10. The system of claim 9, where c is non-zero.

11. The system of claim 9 or 10, wherein a, b, c and d are set up according to an element of a list comprising:an ergonomic parameter, anda light environment parameter.

12. A system for determining a lens element for a potential wearer, the system comprising:a processor (60); anda memory (61) storing instructions that, when executed by the processor, cause the processor to:determine (52) an addition value, ADD, according to any one of the preceding claim, and determine (54) the lens element by selecting, generating, manufacturing or configuring the lens element based on the determined addition value.

13. A method for determining (52) an addition value, ADD, using a relation of the form ADD = EXP(f),where f is a linear function including at least one variable representing a characteristic of the potential wearer.

14. A method for determining (54) a lens element for a potential wearer, the method comprising:determining (52) an addition value, ADD, using a relation of the form ADD = EXP f), where f is a linear function including at least one variable representing a characteristic of the potential wearer, anddetermining (54) the lens element by selecting, generating, manufacturing or configuring the lens element based on the determined addition value.

15. A computer program comprising instructions which, when executed by a processor (60), cause the processor to perform a method according to claim 13 or 14.

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