Generation of nomograms for refractive ophthalmology

Abstract

A system for generating an ophthalmic nomogram for treating an eye includes a computer. The computer stores post-operative refractive data. The post-operative refractive data includes notations that include sphere and cylinder and describe the post-operative correction. The computer creates a nomogram data set including a selected sphere by determining, for each notation, if the notation is expressed as a plus notation, a minus notation corresponding to the plus notation, if the notation is expressed as a minus notation, identifying whether the plus notation or the minus notation has a lower absolute value sphere, designating the identified notation with the lower absolute value sphere as a candidate sphere, and determining whether to designate the candidate sphere as a selected sphere. The computer program calculates an ophthalmic nomogram from the selected sphere.

Description

[Technical field]

[0001] The present disclosure relates generally to ophthalmic laser surgery systems, and more particularly to generating refractive ophthalmic nomograms. [Background technology]

[0002] Refractive ametropia eye surgeries, such as corneal and intraocular surgeries, use various techniques to correct refractive errors. For example, a laser can be used to reshape the cornea, an intraocular lens can be inserted into the eye to replace the crystalline lens, or a lenticule can be removed from the corneal matrix or inserted into the corneal stroma to correct the refractive error. In reality, the results of real-world surgery vary greatly from a perfect laboratory environment due to subtle differences in, for example, laser systems, intraocular lenses, ablation designs, formulas used to calculate the treatment, surgeons, patients, and operating room environments. This difference can be compensated for using a refractive correction nomogram, which can be calculated for a particular refractive correction system. The nomogram is generated by analyzing data from surgeries previously performed with the system to determine the relationship between the desired target correction and the actual postoperative correction. Summary of the Invention [Means for solving the problem]

[0003] In certain embodiments, a system for generating an ophthalmic nomogram for treating an eye includes a computer. The computer includes a memory and logic. The memory stores a computer program for generating the ophthalmic nomogram and post-operative refractive data. The post-operative refractive data includes notations. Each notation includes a sphere and a cylinder, and describes a post-operative correction associated with a target correction. The target correction has a target sphere. The logic executes the computer program to generate a nomogram data set including a selected sphere. To generate the selected sphere, the logic executes the computer program to: for each notation, if the notation is expressed as a plus notation, determine a minus notation corresponding to the plus notation, if the notation is expressed as a minus notation, determine a plus notation corresponding to the minus notation, identify whether the plus notation or the minus notation has a lower absolute value sphere, designate the identified notation with the lower absolute value sphere as a candidate sphere, and determine whether to designate the candidate sphere as a selected sphere. The computer program calculates the ophthalmic nomogram from the selected sphere.

[0004] Embodiments may include none, one, several, or all of the following features: The logic determines whether to designate a candidate sphere as a selected sphere by determining whether to include or exclude the candidate sphere in the selected sphere if the absolute cylinder of the notation is equal to twice the absolute sphere of the notation. The logic determines whether to designate a candidate sphere as a selected sphere by determining whether the notation describes mixed astigmatism if the absolute cylinder of the notation is not equal to twice the absolute sphere of the notation. The logic determines whether to designate a candidate sphere as a selected sphere by determining whether to include or exclude the candidate sphere if the notation describes mixed astigmatism. The logic determines that the absolute cylinder of the notation is equal to twice the absolute sphere of the notation and performs a distribution procedure to distribute the positive and negative notations of the selected sphere. The logic may perform the distribution procedure by selecting the positive notation sphere if the sphere of the previous iteration was derived from the negative notation and selecting the negative notation sphere if the sphere of the previous iteration was derived from the positive notation. The logic may perform the distribution procedure by randomly selecting either a positively or negatively notated sphere as the selected sphere. The logic calculates an ophthalmic nomogram from the selected spheres by performing, for each selected sphere in the nomogram data set, a determination of a post-operative correction corresponding to the selected sphere and an identification of a target sphere of a target correction associated with the post-operative correction. The logic creates a graph of the post-operative sphere versus the target sphere.The logic may create a graph of the post-operative sphere vs. the target sphere by performing a regression analysis of the post-operative sphere vs. the target sphere to determine a line describing the relationship between the post-operative sphere and the target sphere. The logic may create a graph of the post-operative sphere vs. the target sphere by performing a first regression analysis for a first diopter range of the post-operative sphere vs. the target sphere to determine a first line describing the relationship between the post-operative sphere and the target sphere in the first diopter range and performing a second regression analysis for a second diopter range of the post-operative sphere vs. the target sphere to determine a second line describing the relationship between the post-operative sphere and the target sphere in the second diopter range. The logic calculates an ophthalmic nomogram from the selected spheres by identifying a subset of selected spheres corresponding to a class of patients and calculating an ophthalmic nomogram from the subset of selected spheres. The logic plans a treatment for the eye according to the ophthalmic nomogram. The system may include a laser device for performing the treatment for the eye.

[0005] In certain embodiments, a method for generating an ophthalmic nomogram for treating an eye includes storing, by a computer, a computer program for generating an ophthalmic nomogram and postoperative refractive data. The postoperative refractive data includes notations. Each notation includes a sphere and a cylinder, and describes a postoperative correction associated with a target correction. The target correction has a target sphere. The method includes executing, by a computer, a computer program for generating a nomogram data set including a selected sphere. The computer executing the computer program performs the following steps for each notation to generate a selected sphere: if the notation is expressed as a plus notation, determine a minus notation corresponding to the plus notation; if the notation is expressed as a minus notation, determine a plus notation corresponding to the minus notation; identify whether the plus notation or the minus notation has a lower absolute value sphere; designate the identified notation with the lower absolute value sphere as a candidate sphere; and determine whether to designate the candidate sphere as a selected sphere. The computer executing the computer program includes calculating an ophthalmic nomogram from the selected sphere.

[0006] Embodiments may include none, one, several, or all of the following features: Determining whether to designate a candidate sphere as a selected sphere includes determining whether to include or exclude the candidate sphere from the selected sphere if the magnitude cylinder of the notation is equal to twice the magnitude sphere of the notation. Determining whether to designate a candidate sphere as a selected sphere includes determining whether the notation describes mixed astigmatism if the magnitude cylinder of the notation is not equal to twice the magnitude sphere of the notation. Determining whether to designate a candidate sphere as a selected sphere includes determining whether to include or exclude the candidate sphere from the selected sphere if the notation describes mixed astigmatism. The method includes the steps of determining that the magnitude cylinder of the notation is equal to twice the magnitude sphere of the notation and performing a distribution procedure to distribute positive and negative notations of the selected sphere. The step of calculating the ophthalmic nomogram from the selected spheres includes performing, for each selected sphere in the nomogram data set, a step of determining a post-operative correction corresponding to the selected sphere and identifying a target sphere of a target correction associated with the post-operative correction. The step of calculating the ophthalmic nomogram also includes a step of generating a graph of the post-operative sphere versus the target sphere. The method includes a step of planning a treatment for the eye according to the ophthalmic nomogram.

[0007] In certain embodiments, a system for generating an ophthalmic nomogram for treating an eye includes a computer. The computer includes a memory and logic. The memory stores a computer program for generating the ophthalmic nomogram and post-operative refractive data. The post-operative refractive data includes notations. Each notation includes a sphere and a cylinder and describes a post-operative correction associated with a target correction. The target correction has a target sphere. The logic executes the computer program to generate a nomogram data set including a selected sphere. To generate the selected sphere, the logic executes the computer program to cause, for each notation, if the notation is expressed as a plus notation, to determine a minus notation corresponding to the plus notation, if the notation is expressed as a minus notation, to determine a plus notation corresponding to the minus notation, to identify whether either the plus notation or the minus notation has a lower absolute value sphere, to designate the identified notation with the lower absolute value sphere as a candidate sphere, and to determine whether to designate the candidate sphere as a selected sphere. The logic determines whether to assign the candidate sphere to the selected sphere by determining whether to include or exclude the candidate sphere in the selected sphere if the absolute value cylinder of the notation is equal to twice the absolute value sphere of the notation, determining whether the notation describes mixed astigmatism if the absolute value cylinder of the notation is not equal to twice the absolute value sphere of the notation, and determining whether to include or exclude the candidate sphere if the notation describes mixed astigmatism. The logic performs a distribution procedure that determines that the absolute value cylinder of the notation is equal to twice the absolute value sphere of the notation and distributes the positive and negative notations of the selected sphere. The logic performs the distribution procedure by selecting the positive notation sphere if the sphere of the previous iteration was derived from a negative notation, selecting the negative notation sphere if the sphere of the previous iteration was derived from a positive notation, or randomly selecting either the positive notation or the negative notation sphere as the selected sphere. The logic calculates an ophthalmic nomogram from the selected spheres by, for each selected sphere in the nomogram data set, determining a post-operative correction corresponding to the selected sphere and identifying a target sphere of a target correction associated with the post-operative correction. The logic creates a graph of the post-operative sphere versus the target sphere.The logic can create a graph of the post-operative sphere vs. the target sphere by performing a regression analysis of the post-operative sphere vs. the target sphere to determine a line describing the relationship between the post-operative sphere and the target sphere. The logic can create a graph of the post-operative sphere vs. the target sphere by performing a first regression analysis for a first diopter range of the post-operative sphere vs. the target sphere to determine a first line describing the relationship between the post-operative sphere and the target sphere in the first diopter range and performing a second regression analysis for a second diopter range of the post-operative sphere vs. the target sphere to determine a second line describing the relationship between the post-operative sphere and the target sphere in the second diopter range. The logic calculates an ophthalmic nomogram from the selected spheres by identifying a subset of selected spheres corresponding to a class of patients and calculating an ophthalmic nomogram from the subset of selected spheres. The logic plans a treatment for the eye according to the ophthalmic nomogram. The system includes a laser device for administering treatment to the eye. [Brief description of the drawings]

[0008] [Figure 1] 1 illustrates an example of an ophthalmic laser system for performing refractive treatment on an eye, according to certain embodiments. [Diagram 2] 1 shows an example of an eye with astigmatism. [Figure 3A] 2 illustrates an example of a method for generating an ophthalmic nomogram for refractive treatment of an eye that may be performed by the system of FIG. 1 in accordance with certain embodiments. [Figure 3B] 2 illustrates an example of a method for generating an ophthalmic nomogram for refractive treatment of an eye that may be performed by the system of FIG. 1 in accordance with certain embodiments. [Figure 4] 1 shows an example of a graph of post-operative sphere versus associated target sphere and a best-fit line for two data sets. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009]

[0023] Referring now to the description and drawings, exemplary embodiments of the disclosed apparatus, systems, and methods are shown in detail. The description and drawings are not intended to be exhaustive or to limit the claims to the specific embodiments shown in the drawings and disclosed herein. While the drawings represent possible embodiments, the drawings are not necessarily to scale, and certain features may be simplified, exaggerated, removed, or partially divided in order to better illustrate the embodiments.

[0010] In summary, refractive notations expressed as plus or minus notations are used to represent the target refractive correction and its resulting postoperative correction. Nomograms are used to reduce the difference between the target and postoperative corrections. However, user preferences for plus or minus notations can distort the nomogram. Furthermore, refractive notations for mixed astigmatism can misrepresent the correction and reduce the accuracy of the nomogram. Therefore, in an embodiment of the present invention, data for astigmatism cases are analyzed to compensate for these issues.

[0011] More specifically, when calculating the nomogram, a target correction is compared to a post-operative correction. The target correction is the refractive correction that the procedure is set to perform (e.g., the correction that the laser device is directed to perform), typically in response to instructions from a user such as a surgeon. The post-operative (or achieved) correction is the actual refractive correction resulting from surgery.

[0012] Refractive notation describes the refractive correction. Generally, refractive notation includes sphere, cylinder and axis. Sphere represents the spherical correction (near-sighted or far-sighted) and is equal across all meridians of the eye. The value of sphere indicates the lens power prescribed to correct near-sightedness or far-sightedness. Cylinder and axis describe how the astigmatism correction differs from the spherical correction. Astigmatism occurs because the cornea is not perfectly spherical, so light rays converge to two or more foci. The axis represents the meridian of the astigmatism correction and the cylinder represents the amount of correction. In the case of astigmatism, positive / negative powers and their associated axes can be displayed interchangeably.

[0013] Some users have a preferred cylinder designation, such as plus or minus cylinder designation, which they use more than others. However, preferring one of the plus or minus cylinder designations can lead to the astigmatism correction being mislabeled as a spherical overcorrection or undercorrection. Furthermore, refractive designations for mixed astigmatism mislabel the correction. Mixed astigmatism occurs when light rays converge at one focus in front of the retina and another focus behind the retina. In general, mixed astigmatism does not require spherical correction, only cylindrical correction with axes 90° apart. However, refractive designations for mixed astigmatism include a non-zero spherical component, which can lead to the misleading impression that there is spherical compensation. Thus, embodiments described herein analyze astigmatism cases to reduce user preferences for nomograms and the spurious effects of mixed astigmatism designations.

[0014] 1 illustrates an example of an ophthalmic laser system 10 for performing an ophthalmic treatment on an eye 22, according to certain embodiments. The ophthalmic treatment may be any suitable refractive surgery, such as laser refractive surgery (e.g., laser ablation or photodisruptive surgery), cataract surgery (e.g., intraocular lens surgery), or other surgery for refractive correction. In laser refractive surgery, a laser can ablate the cornea to reshape the cornea, or a laser can photodisrupt the cornea to, for example, reshape the cornea, create a pocket for inserting an implant, or create a lenticule for extraction. In cataract surgery, an intraocular lens can be inserted into the eye to replace the crystalline lens.

[0015] In the illustrated example, system 10 includes a laser device 15, a camera 38, and a control computer 30, coupled as shown. Laser device 15 includes controllable elements such as a laser source 12, a scanner 16, one or more optical elements 17, and / or a focusing objective lens 18, coupled as shown. Computer 30 includes logic 36, memory 32 (which stores a computer program 34 and post-operative refractive data 35), and a display 37, coupled as shown. Any suitable xyz coordinate system may be used. For example, the z direction may be defined by the (e.g., visual or optical) axis of the eye or the direction of propagation of the laser light, with the xy plane being orthogonal to the z direction.

[0016] Turning to the parts of system 10, laser source 12 generates laser light including laser pulses that ablate, photocoagulate, photovaporize, photodisrupt, irradiate, or otherwise interact with tissue of eye 22. Laser source 12 may be an excimer, femtosecond, or other suitable laser and may emit laser light of any suitable wavelength (e.g., infrared or ultraviolet). A laser shot list defines the x and y coordinates of locations to which the laser pulses are directed, as well as the order in which the pulses are directed to perform a refractive treatment.

[0017] The scanner 16 focuses the laser light in the x, y, and / or z directions. The scanner 16 can direct the laser light in any suitable direction. For example, the scanner 16 can include a pair of scanner mirrors actuated by galvanometers that can be tilted about mutually perpendicular axes. As another example, the scanner 16 can include an electro-optic crystal that can electro-optically direct the laser light. As another example, the scanner 16 can include a deformable mirror that can direct the beam in a particular direction.

[0018] One (or more) optical elements 17 direct the laser light towards a focusing objective lens 18. The optical element 17 can act on the laser light (e.g., transmit, reflect, refract, diffract, collimate, condition, shape, focus, modulate, and / or otherwise act on the laser light). Examples of optical elements include lenses, prisms, mirrors, diffractive optical elements (DOEs), holographic optical elements (HOEs), and spatial light modulators (SLMs). In this example, the optical element 17 is a mirror. The focusing objective lens 18 focuses the laser light to a point on the eye 22. In this example, the focusing objective lens 18 is an objective lens.

[0019] The camera 38 records images of the eye 22. Examples of the camera 38 include a video, optical coherence tomography, or eye-tracking camera. The camera 38 delivers image data representative of the recorded images of the eye 22 to the computer 30. The computer 30 can perform image processing on the image data to monitor the treatment of the eye 22. In certain embodiments, the images recorded by the camera 38 can be used to monitor the current application of the pulses.

[0020] In certain embodiments, computer 30 executes computer program 34 to generate a nomogram data set that includes the refractive notations (spheric and astigmatic) selected to generate the nomogram. In these embodiments, post-operative refractive data 35 includes the target corrections and their associated post-operative corrections. The compensations are expressed using refractive notations that include sphere and cylinder, where "sphere" and "cylinder" refer to the spherical and cylindrical values ​​of the notation, respectively.

[0021] In some embodiments, the computer 30 selects a sphere to create a nomogram data set for use in generating the nomogram. In summary, the computer 30 generates a plurality of selected spheres by, for each representation of the data 35, determining a minus representation corresponding to the plus representation if the representation is expressed as a plus representation, determining a plus representation corresponding to the minus representation if the representation is expressed as a minus representation, identifying whether the plus representation or the minus representation has a lower absolute value of sphere ("absolute value sphere"), designating the sphere of the identified representation as a candidate sphere (having the lower absolute value sphere), and performing further analysis, as described in more detail with respect to FIG. 3, to determine whether to designate the candidate sphere as a selected sphere. The computer 30 and / or the surgeon can plan a refractive treatment for the eye according to the ophthalmic nomogram. In certain embodiments, the computer 30 performs other operations to create the nomogram data set, as described in more detail with respect to FIGS. 3 and 4.

[0022] In certain embodiments, computer 30 also controls elements of system 10 according to computer program 34. For example, computer 30 controls elements (e.g., laser source 12, scanner 16, optics 17, and / or focusing objective 18) to focus laser light of laser device 15 on eye 22 according to a laser shot list to perform a refractive treatment. For example, computer 30 can instruct the laser device to perform the refractive treatment as planned according to an ophthalmic nomogram. In response, the laser device performs the refractive treatment.

[0023] FIG. 2 shows an example of an eye 22 with mixed astigmatism. Astigmatism is a condition in which the cornea is not perfectly spherical such that light rays converge to multiple focal points 50 (50a, 50b). Mixed astigmatism occurs when light rays converge to one focal point 50a in front of the retina and another focal point 50b behind the retina. Mixed astigmatism can be described using meridians 52 (52a, 52b). Meridian 52 is a meridian that intersects the optical axis. In this example, meridians 52a, 52b (shown here away from eye 22) are perpendicular to each other, but they do not have to be. Light along meridian 52a converges to focal point 50a, and light along meridian 52b converges to focal point 50b.

[0024] Refractive notation. Refractive notation typically includes sphere, cylinder, and axis, for example -0.25[sphere]-0.5[cylinder] x 90°[axis]. Sphere and cylinder refer to the sphere and cylinder values ​​(typically in diopters), respectively, and axis indicates the meridian (typically in degrees). Sphere represents a spherical correction (near-sighted or far-sighted) that is equal across all meridians of the eye. The sphere value indicates the lens power prescribed to correct near-sightedness or far-sightedness. Cylinder and axis describe how much the astigmatic correction differs from the spherical correction. The axis indicates the meridian where the astigmatic correction differs least from the spherical correction, and cylinder represents that difference.

[0025] Astigmatism correction can be expressed in plus and minus cylinder notation. In plus cylinder notation, the cylinder value is a diopter power that is more convergent than the sphere value. That is, the spherical component represents the most divergent meridian and the cylinder component represents the most convergent meridian. In minus cylinder notation, the cylinder value is a diopter power that is more divergent than the sphere value. That is, the spherical component represents the most convergent meridian and the cylinder component represents the most divergent meridian.

[0026] A positive cylinder notation can be converted to a negative cylinder notation and vice versa. First, the cylindrical and spherical values ​​are algebraically added to get the new spherical value. Second, the sign of the cylindrical value is changed from positive to negative or vice versa. Third, the axis of the cylinder is rotated by 90°. If the axis is less than or equal to 90°, 90° is added to the axis. If the axis is greater than 90°, 90° is subtracted from the axis. In other words, to convert Notation 1 = S1 + C1 x Axis 1 to Notation 2 = S2 + C2 x Axis 2, do the following: S2 = S1 + C1, C2 = -C1, and Axis 2 = Axis 1 ± 90°. As some examples, -0.75+1.25×90° is converted to +0.5-1.25×180°, -0.25-0.5×90°→-0.75+0.5×180°; -1.0+0.75×90°→-0.25-0.75×180°; -0.75+1.25×180°→+0.5-1.25×90°; and -1.00+0.50×90°→-0.50-0.50×0°.

[0027] The nomogram may include any suitable refractive notation or description, such as plus cylinder notation, minus cylinder notation, manifest refractive equivalent (MRSE), defocus equivalence index, cycloplegic measurements, or wavefront measurements. For example, the spherical equivalent (SEQ) may be used. The spherical equivalent is an estimate of the refractive correction that essentially combines the spherical and cylindrical components. The spherical equivalent is calculated by adding half the cylinder value to the sum of the spherical values. For example, if the refractive notation is -3.00+1.00×180°, then the spherical equivalent is -3.00. 1 / 2 (+1.00)=-3.00+0.50=-2.50.

[0028] Astigmatism Notation and Nomogram. Some users have a preferred cylinder notation that they use more than others, for example, plus or minus cylinder notation. However, preferring one of the plus or minus cylinder notations can result in the astigmatism correction being mislabeled as a spherical overcorrection or undercorrection. As an example, if a user prefers the plus cylinder notation of astigmatism, a refraction of +1.00-1.00×0° will be interpreted as a spherical overcorrection of 1.00 D (if myopia is the target correction), and the corresponding notation 0+1.00×90° will represent only astigmatism with no spherical overcorrection. Furthermore, a refraction of -1.00+1.00 0° will represent a myopic undercorrection, and the corresponding parent notation 0-1.00×90° will represent myopic cylinder with no spherical component. Furthermore, this example illustrates the limitations of the SEQ notation. Even though this case is pure astigmatism with no spherical component, the SEQ is -0.50.

[0029] Furthermore, refractive correction notations for mixed astigmatism misrepresent the correction. In short, in the notation of mixed astigmatism, the absolute value of the cylinder ("absolute cylinder") is greater than the absolute value of the sphere ("absolute sphere"). For example, -0.75+1.25×180°→+0.5-1.25×90° is an example of a mixed astigmatism correction. In general, mixed astigmatism does not require a spherical correction, only a cylindrical correction. However, notations describing mixed astigmatism contain a non-zero spherical component, which can be misleading to indicate a spherical correction. For example, the mixed astigmatism notation -0.75+1.25×180°→+0.5 -1.25×90° contains spherical components -0.75 and +0.5, which typically indicate a spherical correction. However, this is not the case for mixed astigmatism descriptions. The first astigmatism portion includes the sphere of the first notation and the axes of the second notation, i.e., 0 -0.75 x 90°. The second astigmatism portion includes the sphere of the second notation and the axes of the first notation, i.e., 0 + 0.5 x 180° (or equivalently, 0°). The resulting descriptions are 0-0.75 x 90°, 0 + 0.5 x 0°. Furthermore, to correct 0-0.75 x 90°, the laser does not change the 90° area at all, but flattens the 180° (or 0°) area by -0.75D. To correct 0 + 0.5 x 0°, the laser does not change the 0° area at all, but steepens the 90° area by +0.5D. That is, the mixed astigmatism notation includes a non-zero spherical component that ultimately does not describe a spherical correction. These misleading non-zero spherical components, when used to generate a nomogram, produce spurious effects.

[0030] 3A, 3B, and 4 illustrate an example of a method for generating an ophthalmic nomogram for ophthalmic treatment of an eye that can be performed by the system 10 of FIG. 1, according to certain embodiments. The method analyzes an astigmatism case to reduce the influence of the spherical component of the astigmatism notation. In certain embodiments, a user can select whether or not to perform the method. In other embodiments, a computer can be programmed to perform the method automatically.

[0031] In this example, a computer of the system 10 performs at least some steps of the method. The computer stores a computer program for generating an ophthalmic nomogram and post-operative refractive data. The post-operative refractive data includes refractive notations describing the target corrections and their associated post-operative corrections. The refractive notations include sphere and cylinder. Logic executes the computer program to select the sphere of the post-operative correction and create a nomogram data set for use in generating the ophthalmic nomogram. The sphere is selected to reduce the spurious effect of user preference for plus or minus notation and misrepresentation of mixed astigmatism of the spherical component.

[0032] The method begins at step 110, where the computer accesses the post-operative refraction data. For each refraction notation, steps 112-140 are performed to obtain a nomogram data set. The computer selects a notation from the post-operative refraction data at step 112. The computer determines at step 114 whether it is a plus notation or a minus notation. If the notation is expressed as a plus notation, the corresponding minus notation is determined. If the notation is expressed as a minus notation, the corresponding plus notation is determined. The computer identifies whether the plus notation or the minus notation has the lower modulus sphere and selects the lower modulus sphere as the candidate sphere at step 116.

[0033] The absolute cylinder |cyl| may be equal to twice the absolute sphere |sph|, i.e. |cyl|=2x|sph|, in step 118. If the user has a preferred cylinder notation, these cases may skew the results. If |cyl|=2x|sph|, the method may proceed to step 120 and include or exclude cases where 1 / 2|cyl|=|sph|. In certain embodiments, the user may select whether to include or exclude such cases from the nomogram data set. In other embodiments, the selection may be predetermined by settings in the computer program. If the 1 / 2|cyl|=|sph| cases are to be included, the method proceeds to step 132. If the 1 / 2|cyl|=|sph| cases are to be excluded, the method proceeds to step 122 and excludes the notation. The method then proceeds to step 124 where the next notation of the postoperative refraction data may be present. If |cyl| is not equal to 2x|sph|, the method proceeds to step 126.

[0034] The case may have mixed astigmatism at step 126. A case may be identified as mixed astigmatism if the absolute cylinder is greater than the absolute sphere for the + and - notations, i.e. |cyl|>|sph|, and the sphere of any notation is not 0D. 0D identifies either pure astigmatism, myopia, or hyperopia. If the notation describes mixed astigmatism, the method proceeds to step 128 and may include or exclude cases of mixed astigmatism to reduce the spurious effect of the spherical component of astigmatism. In certain embodiments, the user may select whether to include or exclude mixed astigmatism cases. In other embodiments, the selection may be predetermined by settings in the computer program. If mixed astigmatism is included at step 128, the method proceeds to step 140. If mixed astigmatism is excluded at step 128, the method proceeds to step 122 and excludes mixed astigmatism notations.

[0035] Table 1 lists example cases for steps 110 to 128 of the present method. [Table 1]

[0036] The computer may perform a distribution procedure in step 132 to reduce the influence of cases with |cyl|=2x|sph| on the nomogram. In certain embodiments, the user may select whether to perform the distribution procedure. In other embodiments, the selection may be predetermined by settings in the computer program. If the distribution procedure is performed in step 132, the method proceeds to step 134 where the computer performs any suitable distribution procedure. For example, the plus or minus notation from which the sphere is selected may alternate in each iteration, and a new iteration begins at step 112 once a new notation is selected. If the sphere in the previous iteration was obtained from a minus notation, the plus notation sphere is selected. If the sphere in the previous iteration was obtained from a plus notation, the minus notation sphere is selected. As another example, the computer may randomly select either a plus notation or a minus notation sphere. The selected sphere is added to the nomogram data set in step 140. If the distribution procedure is not performed in step 132, the method proceeds to step 140 where the candidate sphere is designated as the selected sphere and added to the nomogram data set.

[0037] If in step 126 the representation does not describe astigmatism, then in step 140 the sphere from the representation having the lowest absolute value sphere is added to the nomogram data set. After adding the sphere to the nomogram data set in step 140, the method proceeds to step 124 where there may be a next representation of the post-operative data set of the target corrections and their associated post-operative corrections. If there is a next representation, the method returns to step 112 to select the next representation. If there is not a next representation, the method has completed filling the nomogram data set with the selected sphere. The method proceeds to step 150.

[0038] Steps 150-154 are performed to generate a graph and calculate an ophthalmic nomogram from the selected sphere. The computer plots the post-operative sphere versus the target sphere at step 150. In certain embodiments, for each post-operative sphere in the nomogram data set, the computer identifies a target sphere associated with the post-operative sphere. The computer then generates a graph of the post-operative sphere versus the associated target sphere.

[0039] The computer performs a spherical regression analysis at step 152 to determine a line, e.g., a best fit line, that describes the relationship between the post-operative and target spheres. Any suitable regression analysis (e.g., least squares) may be performed in any suitable manner. For example, the regression may be performed for the entire diopter range of the data, e.g., 0 to -8 in graph 180. As another example, the diopter range may be segmented and a regression analysis performed for each segment, e.g., regressions may be performed separately for 0 to -2, -2 to -4, -4 to -6, and -6 to -8.

[0040] FIG. 4 shows an example of a graph 180 of the postoperative realized sphere and its associated target sphere and best fit line for two data sets. In this example, the perfect fit line represents the postoperative sphere that matches the target sphere. The conventional line is generated from a data set selected according to a method that does not reduce the spurious effect of the astigmatism spherical component (represented by circles). The new line is generated from a data set selected according to a new method described herein that reduces the spurious effect (represented by pluses). As graph 180 shows, the new line is closer to the perfect fit line than the conventional line. This indicates that reducing the influence of the astigmatism notation is likely to reduce the spurious effect.

[0041] The computer can generate a graph from all elements of the nomogram data set or from any suitable subset. The subset that may be selected by the user may be selected according to any suitable factor, such as a particular class of patients. For example, a subset may be associated with patients who refract in a particular way, e.g., objectively, subjectively, cyclo-objectively, and / or cyclo-subjectively, patients in a particular age range, or patients requiring correction within a particular diopter range.

[0042] Referring again to the flow diagram of Figures 3A and 3B, the computer generates a nomogram in step 154 ​​according to the regression analysis. In some types of nomograms, the nomogram can describe the relationship between the postoperative sphere and the target sphere, for example, as a best-fit straight line. The nomogram can indicate adjustments that result in a particular actual postoperative correction. For example, graph 180 shows that the laser device should be programmed to perform a correction of -6.95 diopters to achieve a postoperative correction of -7 diopters. As another example, the laser device should be programmed to perform a correction of 1.05 diopters to achieve a postoperative correction of -1 diopters.

[0043] The computer provides a nomogram to plan the refractive treatment at step 156. In certain embodiments, the computer provides the nomogram to a treatment planning program so that the computer and / or surgeon can plan the refractive treatment of the eye according to the ophthalmic nomogram. For example, the planning program can automatically incorporate adjustments indicated by the nomogram into the treatment plan. As another example, the planning program can make the nomogram available to a user to allow the user to determine how to make adjustments. The computer can then generate a laser shot list that will result in the planned refractive treatment.

[0044] The laser device performs the refractive treatment step 158. In certain embodiments, the computer can instruct the laser device to perform the planned refractive treatment according to an ophthalmic nomogram. In this manner, the laser device performs the refractive treatment utilizing the nomogram. The computer can instruct the laser device by transmitting a laser shot list for the treatment, and the laser device performs the treatment by directing laser pulses to the eye according to the laser shot list. The method then ends.

[0045] The elements of the systems and devices disclosed herein (such as computer 30) may include interfaces, logic, and / or memory, any of which may include computer hardware and / or software. An interface can receive input to and / or send output from an element and is typically used to exchange information between, for example, software, hardware, peripheral devices, users, and combinations thereof. A user interface is a type of interface that allows a user to communicate with a computer (e.g., send input to and / or receive output from a computer). Examples of user interfaces include displays, graphical user interfaces (GUIs), touch screens, keyboards, mice, gesture sensors, microphones, speakers, etc.

[0046] Logic can perform the operations of an element. Logic may include one or more electronic devices that process data, e.g., execute instructions to generate output from input. Examples of such electronic devices include computers, processors, microprocessors (e.g., Central Processing Units (CPUs)), computer chips, etc. Logic may include computer software that encodes instructions executable by the electronic devices to perform operations. Examples of computer software include computer programs, applications, operating systems, etc.

[0047] A memory can store information and may include a tangible, computer-readable and / or computer-executable storage medium. Examples of memory include computer memory (e.g., random access memory (RAM) or read-only memory (ROM)), mass storage media (e.g., hard disks), removable storage media (e.g., compact discs (CDs) or digital video or versatile discs (DVDs)), databases, network storage (e.g., server or cloud-based storage), and / or other computer-readable media. Certain embodiments may be directed to memory encoded with computer software.

[0048] Although the present disclosure has been described in terms of specific embodiments, modifications (alterations, substitutions, additions, deletions, and / or other changes) of the embodiments will be apparent to those skilled in the art. Thus, modifications can be made to the embodiments without departing from the scope of the present invention. For example, modifications can be made to the systems and devices disclosed herein. Elements of the systems and devices can be integrated or separated, and operations of the systems and devices can be performed by more, fewer, or other elements, as will be apparent to those skilled in the art. As another example, modifications can be made to the methods disclosed herein. These methods can include more or fewer steps, and the steps can be performed in any suitable order, as will be apparent to those skilled in the art. The computer can be part of a system, a cloud server, or an artificial intelligence environment.

[0049] To assist the Patent Office and readers in interpreting the claims, Applicant notes that no claim or claim element is intended to invoke 35 U.S.C. §112(f) unless the phrase "means for" or "step for" is expressly used in a particular claim. Applicant understands the use of other terms in the claims (e.g., "mechanism," "module," "instrument," "unit," "element," "element," "member," "apparatus," "machine," "system," "processor," or "controller") to refer to structures known to those of ordinary skill in the relevant art and are not intended to invoke 35 U.S.C. §112(f).

Claims

1. 1. A system for generating an ophthalmic nomogram for an eye treatment, the system comprising: a computer; The computer, a memory configured to store a computer program for generating an ophthalmic nomogram and post-operative refraction data, the post-operative refraction data including a plurality of notations, each notation including a sphere and a cylinder, each notation describing a post-operative correction associated with a target correction, the target correction having a target sphere; logic configured to execute the computer program to generate a nomogram data set including a plurality of selected spheres; and wherein the logic for executing the computer program comprises: To generate the plurality of selected spheres, for each representation of the plurality of representations, if said notation is expressed as a plus notation, determining a minus notation that corresponds to said plus notation; if the notation is expressed as a negative notation, determining a positive notation that corresponds to the negative notation; Identifying whether the positive notation or the negative notation has a lower modulus sphere; designating the lower modulus sphere of said identified representation as a candidate sphere; determining whether to designate the candidate sphere as a selected sphere; Calculating the ophthalmic nomogram from the plurality of selected spheres. A system that is configured to perform the following:

2. The logic comprises: determining whether to include or exclude the candidate sphere from the plurality of selected spheres if the modulus cylinder of the representation is equal to twice the modulus sphere of the representation; The system of claim 1 , configured to determine whether to designate the candidate sphere as a selected sphere by:

3. The logic comprises: determining whether the representation represents mixed astigmatism if the magnitude cylinder of the representation is not equal to twice the magnitude sphere of the representation; The system of claim 1 , configured to determine whether to designate the candidate sphere as a selected sphere by:

4. The logic comprises: determining whether to include or exclude the candidate sphere if the representation describes a mixed astigmatism; The system of claim 1 , configured to determine whether to designate the candidate sphere as a selected sphere by:

5. The logic comprises: determining that the modulus cylinder of said notation is equal to twice the modulus sphere of said notation; performing a distribution procedure for distributing the positive and negative representations of the plurality of selected spheres; The system of claim 1 configured for:

6. The logic comprises: if the sphere of the previous iteration was obtained from said minus notation, selecting said plus notation sphere; and if the sphere of the previous iteration was obtained from the plus notation, selecting the sphere of the minus notation. The system of claim 5 , configured to perform the distribution procedure by:

7. The logic comprises: Randomly selecting either the positively or negatively indicated sphere as the selected sphere. The system of claim 6 , configured to perform the distribution procedure by:

8. The logic comprises: For each selected sphere of the nomogram data set, Determining a postoperative correction corresponding to the selected sphere; performing identifying the target sphere of the target correction associated with the post-operative correction; and Creating a graph of post-operative sphere versus the target sphere 2. The system of claim 1, configured to calculate the ophthalmic nomogram from the plurality of selected spheres by executing:

9. The logic comprises: performing a regression analysis of the post-operative sphere versus the target sphere to determine a line representing the relationship between the post-operative sphere and the target sphere; 9. The system of claim 8, configured to generate the graph of the post-operative sphere versus the target sphere by:

10. The logic comprises: performing a first regression analysis for a first range of diopters of the post-operative sphere versus the target sphere to determine a first straight line describing the relationship between the post-operative sphere and the target sphere in the first range of diopters; and performing a second regression analysis for a second range of diopters of the post-operative sphere versus the target sphere to determine a second straight line describing the relationship between the post-operative sphere and the target sphere in the second range of diopters; 9. The system of claim 8, configured to generate the graph of the post-operative sphere versus the target sphere by:

11. The logic comprises: identifying a subset of the plurality of selected spheres that correspond to a class of patients; and calculating said ophthalmic nomogram from said subset of said plurality of selected spheres; 2. The system of claim 1, configured to calculate the ophthalmic nomogram from the plurality of selected spheres by:

12. The logic further comprises: Plan eye treatment according to said ophthalmic nomogram The system of claim 1 configured for:

13. Laser device configured to perform eye treatment The system of claim 12 further comprising:

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