CH709124B1 - Equipment for the correction of presbyopia. - Google Patents

Abstract

An apparatus for correcting presbyopia comprising: a laser device (2) for refractive surgery; a control device (3) of the laser device (2), the control device (3) being configured to command the laser device (2) to perform the following two ablation steps on a human cornea (4), corresponding to of two corresponding concentric optical zones centered on the center of the cornea (4): carry out a phase of positive ablation of the cornea (4) according to a first correction value between +1.3 and +1.7 spherical diopters, in a first circular optical zone (9) of intervention, having a first diameter (9a), and with a first transition zone (10) extending from the first diameter (9a) to a second diameter (10a), greater than the first diameter ( 9a); and carrying out a phase of negative ablation of the cornea (4) in accordance with a second correction value comprised between –1.1 and –1.5 spherical diopters, in a second circular optical area of intervention, having a third diameter (11a) lower than the first diameter (9a), and with a second transition zone (12) extending from the third diameter (11a) to a fourth diameter (12a), greater than the third diameter (11a).

Description

Description [0001] The present invention relates to an apparatus for correcting presbyopia in patients presenting such a visual defect, according to claim 1. The present invention also finds particular application for the correction of presbyopia in patients with presumptive emmetropia or pure presbyopites, i.e. substantially presenting only the visual defect of presbyopia. It is known that visual defects, such as myopia, hypermetropia, astigmatism and presbyopia, can originate from conditions of the cornea that do not allow images to be focused on the retina and consequently do not allow good visual acuity, as occurs in emmetropic individuals, which have no visual defects. Depending on whether it is myopia, hypermetropia, astigmatism or mixed defects (hypermetropic astigmatism, myopic astigmatism) the corneal surface is too curved, too flat, or has other irregularities that do not allow images to be properly focused. The traditional techniques for the correction of visual defects, foresee the use of corrective lenses mounted on glasses or contact lenses, but these techniques oblige the subject to the daily use of corrective devices, sometimes uncomfortable and not optimal in the correction. In recent decades, various techniques of ocular microsurgery or refractive surgery have also been developed which allow the visual defects to be corrected often, eliminating the need to use corrective lenses. These refractive surgery techniques intervene on the cornea or on the lens, allowing the image to form on the retina again and thus correcting the visual defect. The various techniques available include for example Lasik, PRK, Lasek, etc.

[0002] These techniques involve the use of laser beam equipment, typically an excimer laser. The excimer laser is normally used to correct defects by far (myopia, astigmatism and hypermetropia). Presbyopia is instead traditionally corrected only by contact lenses or mounted on glasses. The pre-sbiopic defect affects almost all the population from the age of 40-50 years, as it is, unlike the other refractive defects, a malfunction of the lens and of the accommodating muscles, deriving from the normal aging process individual. In fact, the focus of a nearby object is the result of the action of the ciliary muscle which, by contracting, acts on the elasticity of the crystalline lens, making it assume a more or less spherical shape depending on the distance from the object to be focused. The accommodative capacity is progressively reduced with advancing age, starting precisely from 40/45 years, and evolves towards the 65/70 years. Some applications have been proposed for the correction also of presbyopia (near defect) using excimer lasers, but the results of these techniques are not yet completely satisfactory, due to some residual problems due to an insufficient quality of vision (including with for example the presence of halos around light sources, an unclear perception of lights, problems with vision and driving of night vehicles), as well as slow regression towards the presbyopic symptom. Moreover, the known techniques do not allow a satisfactory correction of presbyopia alone in individuals who do not present other visual defects. Presbyopia correction techniques using refractive surgery are for example described in patent documents WO 2006 012 947 A2 (of the same Applicant), US 2001 031 959 A1 and US 2002 075 451 A1. These techniques, though praiseworthy, do not yet allow for a completely satisfactory visual result in the correction of presbyopia. Techniques are also known that allow correction of visual defects by means of intra-ocular corrective lenses, which are surgically inserted into the eye and allow improvement or correction of some types of visual defects. Moreover, techniques have been recently invented, from the same inventor of the present invention, which allow stabilization of the cornea by transepithelial cross-linking, by application of a substance, riboflavin, derived from vitamin B12, marketed under the Paracel ™ brand from AVEDRO in a particularly formulation, and by emission of ultraviolet energy, UV-A rays, on the part to be treated. In particular, the PiXL ™ technique, an acronym for "Photorefractive Intrastromal Cross-Linking" consists precisely in an Intrastromal Photorefractive Cross-Linking, which can be implemented by the KXL II ™ machine of the American company AVEDRO. In a few minutes the corneal stroma, the part immediately below the outer layer of the cornea, receives a consolidation of its structure and a lowering of its surface. The consolidation of the collagen fibers present in the corneal stroma is at the base of the cross-linking principle, that is the creation of new cross-links which, like a very thin but very resistant net, strengthens the cornea and therefore finds a further indication in the treatment of keratoconus. By means of this technique it is possible to modify the conformation of a portion of the cornea, and therefore it is possible to use this technique for example to correct minor myopia, as an alternative to traditional laser surgery techniques.

[0003] In light of the above, the technical task of the present invention is to provide an apparatus for correcting presbyopia which allows to overcome or at least reduce the drawbacks encountered in the known art. It is also the purpose of the invention to realize a device for the correction of presbyopia that allows to restore a high visual quality close to presbyopic patients. It is also the purpose of the invention to realize an apparatus for the correction of presbyopia particularly suitable for patients with presumptive emmetropia, that is, substantially presenting only the visual defect of presbyopia. It is also the purpose of the invention to realize a device for the correction of presbyopia that allows to offer a high overall visual quality, both from near and far, to treated patients. It is also the purpose of the invention to provide an apparatus for the correction of presbyopia which is reliable and repeatable. It is also the purpose of the invention to provide an apparatus for the correction of presbyopia which is adaptable to the needs of each patient. It is also the purpose of the invention to provide an apparatus for the correction of presbyopia which is not complex to build and has a low overall cost. These aims and others, which will become clearer in the course of the following description, are substantially achieved by an apparatus for correcting presbyopia according to what is expressed in one or more of the appended claims, taken alone or in combination with one another, or in any combination with one or more of the additional aspects described below. Moreover, each of the aspects described below can be taken alone or in any combination with the other aspects described, and also in combination with any of the claims of the application or with any combination of such claims. In particular, the present invention also describes an apparatus for the correction of presbyopia comprising a laser device for refractive surgery and a control device of the laser device, in which the control device is configured to command the laser device to perform at least the following phase of positive ablation on a human cornea, in correspondence of an optical zone centered on the center of the cornea: carry out a phase of positive ablation of the cornea according to a first correction value between +1.3 and +1.7 spherical diopters, in a first circular optical zone of intervention, having a first diameter, and with a first transition zone extending from the first diameter to a second diameter, greater than the first diameter. More particularly, the control device is configured to command the laser device also to perform the following negative ablation step on a human cornea, at a second optical zone centered on the center of the cornea and concentric to the first optical zone: performing a phase of negative ablation of the cornea according to a second correction value comprised between -1.1 and -1.5 spherical diopters, in a second circular optical zone of intervention, having a third diameter smaller than the first diameter, and with a second transition zone extending from the third diameter to a fourth diameter, greater than the third diameter.

In detail, the first optical zone has a first diameter between 4.8 mm and 6.8 mm or between 5.2 mm and 6.4 mm or between 5.6 mm and 6 mm or between 5.7 and 5.9 mm. In detail, the first transition zone extends to a second diameter between 8 mm and 9.8 mm or between 8.7 mm and 9.3 mm or between 8.9 mm and 9.2 mm or inclusive. between 9 mm and 9.1 mm. In detail, the second diameter is greater than the first diameter by a value between 2 mm and 4 mm or between 3 mm and 3.5 mm or between 3.1 mm and 3.4 mm. In detail, the second optical zone has a third diameter between 4.5 mm and 6.5 mm or between 4.9 mm and 6.1 mm or between 5.3 mm and 5.7 mm or between 5.4 and 5.6 mm. In detail, the third diameter is smaller than the first diameter by a value between 0.2 mm and 0.5 mm or a value between 0.25 mm and 0.35 mm or between 0.27 mm and 0 , 33 mm or between 0.29 mm and 0.31 mm. In detail, the second transition zone extends to a fourth diameter between 7.5 mm and 9.5 mm or between 8 mm and 9 mm or between 8.3 mm and 8.8 mm. In particular, the fourth diameter is smaller than the second diameter of a value between 0.1 mm and 1 mm, or between 0.2 mm and 0.8 mm, or between 0.3 mm and 0.6 mm, or between 0.4 mm and 0.5 mm. In particular, the fourth diameter is greater than the third diameter by a value between 2 mm and 4 mm or between 2.8 mm and 3.4 mm or between 3 mm and 3.2 mm. In particular, the control device 3 is configured and designed to perform the corneal ablation phases 4, or the phase of modifying the cornea 4, on a pure presbyopic patient, ie only presbyopite or emmetropic presbyopites.

[0004] In addition, an apparatus for presbyopia correction is further described which also comprises an eye sighting device, called eye-tracker, and in which the control device is configured to control the execution of said phases to the laser device. ablation in a way centered on the center of the cornea after activation of the eye aiming device. Also described here is an apparatus for presbyopia correction in which the control device is configured to command the laser device to perform the ablation steps on an internal portion of the human cornea, called the stroma, exposed by creating a flap of cornea, by means of a mechanical microkeratome or femtosecond or femtolaser laser, and temporary displacement of the same flap, as part of an ocular microsurgery operation, for example of the LASIK type. Also described here is an apparatus for correcting presbyopia in which the laser device is of the excimer type. In particular, the control device is configured to maintain the corneal curvature K value or original corneal keratometry substantially unaltered following the execution of the ablation steps. In particular, an interfacial data support can also be provided with a control device, or with a computer operatively active on the control device, of a laser device, for example with excimer devices, on which support is stored a program able to operate on the device. control. In particular, the control device is configured to command the laser device to perform a single ablation phase on a human cornea performed at a single optical zone centered on the center of the cornea, defining a corresponding overall profile on the cornea to that defined by the execution of the phase of positive ablation and the phase of negative ablation. Also described here is an apparatus for correcting presbyopia comprising a laser device for refractive surgery; a control device of the laser device, the control device being configured to command the laser device to perform a single ablation phase on a human cornea performed at a single optical zone centered on the center of the cornea, defining on the cornea a profile corresponding to the overall profile defined by the execution of the following ablation phases on a human cornea, performed in correspondence of two corresponding concentric optical zones and centered on the center of the cornea: carry out a phase of positive ablation of the cornea in agreement with a first correction value comprised between +1.3 and +1.7 spherical diopters, in a first circular optical zone of intervention, having a first diameter, and with a first transition zone extending from the first diameter to a second diameter, greater than the first diameter; and effecting a phase of negative ablation of the cornea in accordance with a second correction value comprised between -1.1 and -1.5 spherical diopters, in a second circular optical zone of intervention, having a third diameter smaller than the first diameter, and with a second transition zone extending from the third diameter to a fourth diameter, greater than the third diameter. In particular, the first correction value is between +1.4 and +1.6 spherical diopters or in which the first correction value is +1.5 spherical diopters and / or in which the second correction value is included between -1.2 and -1.4 spherical diopters or in which the second correction value is -1.3 spherical diopters. Also described is the use of an apparatus for the correction of presbyopia as claimed and / or according to the above mentioned aspects, in which the ablation phases are performed on a pure presbyopic patient, ie only presbyopite or emmetropic presbyopites.

[0005] A process for the correction of the presbyopia by means of a laser beam for refractive surgery not forming part of the claims and herein expressed purely for the purpose of completeness of description is also described. The method comprises the steps of carrying out a phase of positive ablation of the cornea 4 in accordance with a first correction value between +1.3 and +1.7 spherical diopters, or between +1.4 and +1.6 diopters spherical, or +1.5 spherical diopters, in a first optical zone 9 of circular intervention, centered on the center of the cornea 4 and having a first diameter 9a, and with a first transition area 10 extending from the first diameter 9a to a second diameter 10a, greater than the first diameter 9a; and carrying out a phase of negative ablation of the cornea 4 according to a second correction value between -1.1 and -1.5 spherical diopters, or between -1.2 and -1.4 spherical diopters, or of -1 , 3 spherical diopters, in a second circular optical intervention zone, centered on the center of the cornea 4 and concentric to the first optical zone 9, having a third diameter 11 lower than the first diameter 9a, and with a second transition zone 12 extending from the third diameter 11a to a fourth diameter 12a, greater than the third diameter 11 a.

[0006] A procedure is also described for the correction of presbyopia by means of Intrastomal Photorefractive Cross-Linking, which is not part of the claims and is expressed here for the sole purpose of completeness of description. The process comprises the step of applying a riboflavin-containing substance to a human cornea 4 and the step of modifying this human cornea 4, by emitting ultraviolet energy on the part to be treated, to achieve on this human cornea a profile corresponding to a resulting curve from the execution of the following two ablation steps, in correspondence of two corresponding concentric optical zones and centered on the center of the cornea 4: a phase of positive ablation of the cornea 4 according to a first correction value between +1.3 and + 1.7 spherical diopters, or between +1.4 and +1.6 spherical diopters, or +1.5 spherical diopters, in a first optical zone 9 of circular intervention, centered on the center of the cornea 4 and having a first diameter 9a, and with a first transition area 10 extending from the first diameter 9a to a second diameter 10a, greater than the first diameter 9a; and a phase of negative ablation of the cornea 4 according to a second correction value comprised between -1.1 and -1 spherical diopters, or between -1.2 and -1.4 spherical diopters, or of -1, 3 spherical diopters, in a second circular optical intervention zone, centered on the center of the cornea 4 and concentric to the first optical zone 9, having a third diameter 11 lower than the first diameter 9a, and with a second transition zone 12 extending from the third diameter 11a at a fourth diameter 12a, greater than the third diameter 11a. In particular, the third diameter 11a is lower than the first diameter 9a by a value between 0.1 mm and 0.7 mm, or between 0.2 and 0.5 mm, or between 0.25 and 0.40 mm, or between 0.27 mm and 0.33 mm. In particular, the first optical zone 9 has a first diameter 9a comprised between 4.5 mm and 7 mm or between 5.2 mm and 6.4 mm and / or in which the first transition zone 10 extends up to a second diameter 10a of between 7.5 mm and 10.5 mm or between 8.7 mm and 9.3 mm and / or higher than the first diameter 9a of a value between 1.5 mm and 4.5 mm or between 3 mm and 3.5 mm. In particular, the second optical zone has a third diameter 11a comprised between 4 mm and 6.5 mm or between 4.9 mm and 6.1 mm and / or in which the second transition zone 12 which extends to a quarter diameter 12a between 7 mm and 10 mm or between 8 mm and 9 mm and / or higher than the third diameter 11 a of a value between 1.5 mm and 4.5 mm or between 2.8 mm and 3.4 mm.

[0007] In particular, the emission of ultraviolet energy takes place by emission of UVA rays with a power of 25-50 mW / cm2, in particular of 30—45 mW / cm2, preferably of 45 mW / cm2, for a duration between 1 minute and 5 minutes, or between 1.5 minutes and 3 minutes, preferably between 2 and 2.5 minutes, for example 2.4 minutes.

[0008] In particular, a phase of positive ablation of the cornea may be present according to a first correction value between +1.3 and +1.7 spherical diopters, or between +1.4 and +1.6 spherical diopters , or of 1.5 spherical diopters, in a first circular optic zone of intervention, centered on the center of the cornea and having a first diameter, and with a first transition zone extending from the first diameter to a second diameter, greater than the first diameter . In particular, a phase of negative ablation of the cornea may be present according to a second correction value between -1.1 and -1.5 spherical diopters, or between -1.2 and -1.4 spherical diopters, or of - 1.3 spherical diopters, in a second circular optic zone of intervention, centered on the center of the cornea and concentric to the first optical zone, having a third diameter smaller than the first diameter, and with a second transition zone extending from the third diameter to a fourth diameter, greater than the third diameter. In particular, before the ablation phases, one or more of the following phases may be present: making an incision on a human cornea to make a corneal flap; move the corneal flap to leave a portion of the underlying cornea or stroma exposed; trace the center of the human cornea using a sighting device or eye-tracker. After the ablation phases, the phase of repositioning the corneal flap in its original position may be present. Also, two phases of corneal ablation can be present, consisting exactly in the phase of positive ablation and in the phase of negative ablation of the cornea described above. The ablation phases are performed on a pure presbyopic patient, ie only presbyopite or emmetropic presbyopite. A phase can be present to define on the human cornea, by means of the two ablation phases, or by modifying the human cornea, a conformation consisting of a single continuous curve, in particular of the aspherical type. The phase of positive ablation can be performed before the phase of negative ablation or alternatively the phase of negative ablation is carried out before the phase of positive ablation. Alternatively, the phase of positive ablation and the phase of negative ablation are performed simultaneously by means of a single phase of ablation in a single optical zone defining the same overall profile resulting on the cornea. Alternatively, a single corneal ablation phase performed at a single optical zone centered on the center of the cornea can be provided and defining an overall profile on the cornea corresponding to the one definable a phase of positive ablation of the cornea according to a first correction value between +1.3 and +1.7 spherical diopters, or between +1.4 and +1.6 spherical diopters, or +1.5 spherical diopters, in a first circular optical area of intervention, centered on the center of the cornea and having a first diameter, and with a first transition zone extending from the first diameter to a second diameter, greater than the first diameter; and a phase of negative ablation of the cornea according to a second correction value between -1.1 and -1.5 spherical diopters, or between -1.2 and -1.4 spherical diopters, or -1.3 spherical diopters, in a second circular optic zone of intervention, centered on the center of the cornea and concentric to the first optical zone, having a third diameter smaller than the first diameter, and with a second transition zone extending from the third diameter to a fourth diameter, greater than the third diameter.

[0009] The detailed description of one or more preferred embodiments of the invention, in which: FIG. 1 is a schematic view of a first embodiment of an apparatus for correcting presbyopia operating on a human cornea; fig. 2 is a schematic front view of a human cornea, with a surface flap displaced laterally, and before treatment with the apparatus for correction of the presbyopia of fig. 1; fig. 3 is a view similar to that of fig. 2, in which both the optical zones and the transition zones are schematically indicated in a contextual manner, with the relative diameters, relating to two ablation phases which must be carried out by the apparatus for the correction of presbyopia; fig. 4 is a side view in section of the cornea of fig. 2, which indicates the optical zone and the transition zone of the phase of positive ablation of the cornea performed by the apparatus for the correction of presbyopia, with a schematic indication of the removal of material that is carried out in this phase; fig. 5 is a view similar to that of fig. 4, which indicates the optical zone and the transition zone of the phase of negative ablation of the cornea performed by the apparatus for the correction of presbyopia, with a schematic indication of the removal of material that is carried out in this phase.

[0010] An apparatus 1 for the correction of the presbyopia according to one or more embodiments of the invention will be described below. The apparatus 1 comprises a laser device 2 for refractive surgery, preferably of the excimer type. The apparatus 1 further comprises a control device 3 of the laser device 2, configured to command the laser device 2 to carry out the following two ablation steps on a human cornea 4, in correspondence of two corresponding concentric optical zones and centered on the center of the cornea 4. The phase of positive ablation of the cornea 4 is carried out in accordance with a first correction value of between +1.3 and +1.7 spherical diopters, in a first optical zone 9 of circular intervention, having a first diameter 9a, and with a first transition zone 10 extending from the first diameter 9a to a second diameter 10a, greater than the first diameter 9a. In the present text the term "between" is understood to include the extremes of the indicated interval. The first correction value is preferably between +1.4 and +1.6 spherical diopters. In a first preferred embodiment, the first correction value is +1.5 spherical diopters. The negative ablation phase, which can be carried out after the positive ablation phase (or in an alternative form before this phase), is a phase of negative ablation of the cornea 4 according to a second correction value included between -1, 1 and -1.5 spherical diopters, in a second optical circular area 11 for intervention, having a third diameter 11a lower than the first diameter 9a, and with a second transition area 12 extending from the third diameter 11a to a fourth larger diameter 12a compared to the third diameter 11 a. The second correction value is preferably between -1.2 and -1.4 spherical diopters. In the first preferred embodiment, the second correction value is -1.3 spherical diopters. The optical areas of intervention are centered on the center of the cornea 4 and preferably have a diameter greater than that of the maximum pupillary dilation of the eye. The optical areas of intervention are therefore prolonged with corresponding marginal circular transition zones in which the depth of intervention gradually decreases to zero. In other words, in the present text the term "transition zone" means an intermediate zone between the first optical zone 9, or the second optical zone 11, in which the appropriate correction is made to obtain the desired dioptric correction, and a external area where no ablation is performed. This «transition zone» constitutes essentially a «connection» zone, in which the depth of ablation gradually decreases starting from the determined depth at the outer end of the optical zones until it becomes zero at the outer end of the «transition zone» same. The transition zones can have proportional amplitude with respect to the corresponding optical intervention area. The first optical zone 9 can have a first diameter 9a comprised between 4.5 mm and 7 mm. Preferably, the first diameter 9a can be between 4.8 mm and 6.8 mm or between 5.2 mm and 6.4 mm. In further preferred forms the first diameter 9a can be between 5.6 mm and 6 mm or advantageously between 5.7 and 5.9 mm. In a first preferred and particularly advantageous embodiment, the first diameter 9a is 5.8 mm. The first transition zone 10 can extend up to a second diameter 10a comprised between 7.5 mm and 10.5 mm. In further preferred forms the second diameter 10a can be between 8 mm and 9.8 mm or between 8.7 mm and 9.3 mm. In the first embodiment the second diameter 10a is between 8.9 mm and 9.1 mm. The second diameter 10a can be higher than the first diameter 9a by a value between 1.5 mm and 4.5 mm. Preferably the second diameter 10a can be higher than the first diameter 9a by a value between 2 mm and 4 mm or between 3 mm and 3.5 mm. Advantageously, this value can be between 3.1 mm and 3.4 mm. In the first embodiment this value is 3.2 mm. The second optical zone 11 can have a third diameter 11a comprised between 4 mm and 6.5 mm. The third diameter 11a is preferably between 4.5 mm and 6.5 mm or between 4.9 mm and 6.1 mm. Advantageously, the third diameter 11a can be between 5.3 mm and 5.7 mm or even more preferably between 5.4 and 5.6 mm. In the first embodiment the third diameter 11a is 5.5 mm. The third diameter 11a, i.e. the diameter of the second optical zone 11, may be smaller than the first diameter 9a by a value between 0.1 mm and 0.7 mm, or between 0.2 mm and 0.5 mm. Preferably this value is between 0.25 mm and 0.40 mm and even more preferably it is between 0.27 mm and 0.35 mm. Advantageously, this value is between 0.27 mm and 0.33 mm or between 0.29 mm and 0.31 mm. Advantageously, in the first embodiment of the present invention, this value is 0.3 mm. The second transition zone 12 can extend up to a fourth diameter 12a comprised between 7 mm and 10 mm. Preferably the fourth diameter 12a is between 7.5 mm and 9.5 mm or between 8 mm and 9 mm. Still more preferably the fourth diameter 12a is between 8.3 and 8.8 mm. In the first embodiment of the present invention, the fourth diameter 12a is between 8.5 mm and 8.7 mm. The fourth diameter 12a can be smaller than the second diameter 10a by a value between 0.1 and 1 mm, preferably between 0.2 and 0.8 mm, even more preferably between 0.3 and 0.6 mm. In the first embodiment of the present invention, this value is between 0.4 mm and 0.5 mm. The fourth diameter 12a can be higher than the third diameter 11a by a value between 1.5 mm and 4.5 mm. The fourth diameter 12a is preferably higher than the third diameter 11a of a value between 2 mm and 4 mm or between 2.5 mm and 3.5 mm. Still more preferably the fourth value is between 2.8 mm and 3.4 mm. In the first embodiment this value is between 3 mm and 3.2 mm. The above indicated diameters can be chosen within the ranges indicated also compatibly with the dimensions of the cornea 4 of the specific patient, which normally can have a "white to white" diameter of between about 10.5 mm and about 12.5 mm . The control device 3 can be configured to perform only two phases of ablation of the cornea 4, consisting exactly in the phase of positive ablation and in the phase of negative ablation of the cornea 4 described above, without further ablation steps. The control device 3 is preferably configured and designed to perform these phases of ablation of the cornea 4 on a pure presbyopic patient, ie only presbyopite or emmetropic presbyopites. The control device 3 can also be configured and designed to perform these corneal ablation steps 4 on a presbyopic patient also presenting further visual defects, such as myopia, hypermetropia or astigmatism, by means of a suitable adaptation of the above working parameters. The control device 3 is advantageously configured to define on the human cornea 4, by means of the two ablation steps described above, a conformation consisting of a single continuous curve, in particular of the aspherical type. The apparatus 1 for presbyopia correction can further comprise an eye sighting device, called eye-tracker, not shown in the accompanying figures as it is of a per se known type. The control device 3 is configured to command the laser device 2 to perform the ablation steps centered on the center of the cornea 4 after the activation of the eye target device. The control device 3 is configured to command the laser device 2 to execute the ablation steps on an internal portion 8 of the human cornea 4, said stroma 8, exposed by creating, by means of a microkeratome, which can be of a mechanical type for example or preferably of the femtosecond laser or femtolaser type, and temporary displacement of a cornea or flap flap 7, for example having a thickness of about 100 microns, in the context of an ocular microsurgery operation, for example of the LASIK type. The control device 3 is further configured to maintain, thanks to the work parameters identified above, the K value of corneal curvature or original keratometry of the cornea 4 substantially unchanged following the execution of the ablation steps. The control device 3 is further configured to induce, following the execution of the ablation steps and thanks to the work parameters identified above, controlled aberrations. These controlled aberrations induced by the described ablation phases include at least an increase in the negative aberrations of the eye (which grow in the negative sense) and an induction or growth of the "coma" (which grow in a positive sense). For the execution of the analysis of the case an aberrometer, an instrument measuring the aberrations of the eye, can be used to carry out the so-called «wavefront analysis». The above parameters can be set manually on the control device 3 directly by the doctor before performing the correction of presbyopia. The laser control device 3 can be interfaced with a computer 5 provided with an input device 6, by means of which a doctor can import the working parameters in a simplified or guided manner and also manage further functions, as illustrated in fig. 1.

[0011] A computer program is provided which is configured to operate on a control device 3 of an excimer laser device 2 to manage its operation and to control the excimer laser device 2 to perform the ablation steps on a human cornea 4 as described above. The program can operate directly on the control device 3 or can operate on the same indirectly, for example by operating on a computer 5 able to pass the working parameters to the control device 3. The invention also relates to an interfaced data support with a control device 3 of a laser device 2 or with a computer 5 operatively active on the control device 3, on which support such program is stored. The data medium can be of any type suitable for the purpose, for example an optical, magnetic, electronic memory, an electromagnetic signal, etc.

[0012] A process for the correction of presbyopia by means of a laser beam for refractive surgery, for example excimer, not forming part of the invention as claimed but described for completeness comprises the step of carrying out a phase of positive ablation of the cornea 4 according to a first correction value between +1.3 and +1.7 spherical diopters, or preferably between +1.4 and +1.6 spherical diopters, in a first optical zone 9 of circular intervention, centered on the center of the cornea 4 and having a first diameter 9a, and with a first transition area 10 extending from the first diameter 9a to a second diameter 10a, greater than the first diameter 9a. In the first preferred embodiment of the invention the first correction value is 1.5 spherical diopters. The process further comprises a phase of negative ablation of the cornea 4 according to a second correction value comprised between -1.1 and -1.5 spherical diopters, or preferably between -1.2 and -1.4 spherical diopters, in a second circular optical zone 11 for intervention, centered on the center of the cornea 4 and concentric to the first optical zone 9, having a third diameter 11 lower than the first diameter 9a, and with a second transition zone 12 extending from the third diameter 11a to a quarter diameter 12a, greater than the third diameter 11 a. In the first preferred embodiment of the invention the second correction value is -1.3 spherical diopters. The phase of positive corneal ablation is preferably performed before the negative ablation phase. In an alternative embodiment, the negative ablation step can be performed before the positive ablation step. The process can further comprise, before the ablation steps, one or more of the following steps: making an incision on a human cornea 4 to make a corneal flap 7; moving the corneal flap 7 to leave a portion 8 of the underlying cornea 4 or stroma 8 exposed; trace the center of the human cornea 4 using a sighting device or eye-tracker. After the ablation phases, the corneal flap 7 is then repositioned to its original position. Preferably the process comprises only two ablation phases of the cornea 4, consisting exactly in the phase of positive ablation and in the phase of negative ablation of the cornea 4 described above. Thanks to the two ablation steps indicated and the relative operating parameters, the process also allows the definition defined on the human cornea 4, by means of the two described ablation phases, of a conformation constituted by a single continuous curve, in particular of the aspherical type. Preferably the described ablation steps are performed on a pure presbyopic patient, i.e. only presbyopite or emmetropic presbyopite. The method may comprise the further technical characteristics, relating for example to the operating intervals of the parameters, to the steps to be performed, and others, as defined above with reference to the apparatus 1. The first preferred embodiment of the invention is summarized below. invention.

[0013] The procedure is performed on an emmetropic patient (with vision without significant defects) from a distance and affected solely by presbyopia. The intervention technique used is preferably LASIK. A corneal flap 7 is created and then moved to perform ablation on the stroma 8. The aiming device is then activated by hooking it to the center of the cornea 4, in order to perform ablations centered on the center of the cornea 4 and mutually concentric. The control device 3 then commands the excimer laser to perform a first ablation of +1.5 spherical diopters in a first optical zone 9 of 5.8 mm and with a first transition zone 10 of 9.0 mm. In this way, a greater removal of material from the cornea 4 is substantially carried out in the peripheral area of the first optical zone 9 with respect to the center thereof, also connecting the height difference defined by this removal of material through the first transition zone 10. Next, the control device 3 controls the excimer laser to perform a second ablation of -1.3 spherical diopters in a second optical zone 11 of 5.5 mm and with a first transition zone 10 of 8.5 mm. In this way, a greater removal of material of the cornea 4 is substantially carried out in the central area of the second optical zone 11 with respect to the periphery thereof, again linking the difference in level defined by this removal of material through the second transition zone 12. It is then repositioned the corneal flap 7. The conventional eye treatment operations are also performed in the context of a surgical intervention, through the use of anesthetics, disinfectants, etc.

[0014] The present invention allows to obtain one or more of the following advantages. First of all, the invention allows to overcome or significantly reduce the problems encountered in the known art. The invention also allows a high visual quality to be restored close to presbyopic patients. The invention allows in particular to avoid the emergence of visual defects detectable following the corrective intervention. The invention also makes it possible to offer a high overall visual quality, both from near and far, to treated patients. The invention is also adaptable to the needs of each patient. The invention is also reliable and repeatable. Finally, the invention is not complex in construction and convenient to implement.

Claims (4)

claims 1. Apparatus for correcting presbyopia comprising: a laser device (2) for refractive surgery; a control device (3) of the laser device (2), the control device (3) comprising control means of the laser device (2) configured for the execution of an ablation on a human cornea (4), in correspondence with two corresponding concentric optical zones centered on the center of the cornea (4), where the ablation includes: • a positive ablation of the cornea (4) according to a first correction value between +1.3 and +1.7 diopters spherical, in a first optical zone (9) of intervention, having a first diameter (9a), and with a first transition zone (10) extending from the first diameter (9a) to a second diameter (10a), greater than the first diameter (9a); • a negative ablation of the cornea (4) in accordance with a second correction value comprised between -1.1 and -1.5 spherical diopters, in a second circular optical intervention zone, having a third diameter (11a) lower than the first diameter (9a), and with a second transition zone (12) extending from the third diameter (11a) to a fourth diameter (12a), greater than the third diameter (11a). 2. Apparatus for the correction of the presbyopia according to claim 1, wherein the laser device (2) is a Intrastromal Photorefractive Cross-Linking laser and in which said control means are configured to modify a human cornea (4), in particular treated with riboflavin, by emission of ultraviolet energy on the part to be treated to achieve on this human cornea (4) a profile corresponding to a curve resulting from the execution of the two said ablation phases. 3. Apparatus according to one of the preceding claims depending on claim 1, wherein the control device (3) is configured to perform only two ablation phases of the cornea (4), consisting exactly in said positive ablation phase and in said phase of negative ablation of the cornea (4) and / or in which the control device (3) is configured to command the laser device (2) the sequential execution of the two ablation phases, with the execution of the positive ablation phase before the negative ablation phase or in which the control device (3) is configured to command the laser device (2) the sequential execution of the two ablation phases, with the execution of the negative ablation phase before the positive ablation phase. 4. Apparatus according to one of the preceding claims, wherein the control device (3) is configured to define on said human cornea (4), by means of said two ablation steps or by means of said step of modifying the cornea, a conformation consisting of a single continuous curve, in particular of the aspherical type.