EP3052003A1

EP3052003A1 - Method and device for identifying an angle on an eye of a patient

Info

Publication number: EP3052003A1
Application number: EP14790218.3A
Authority: EP
Inventors: Pierre-Antoine FOREST
Original assignee: Cutting Edge
Current assignee: Cutting Edge
Priority date: 2013-10-04
Filing date: 2014-10-02
Publication date: 2016-08-10
Also published as: WO2015019034A1; FR3011461B1; FR3011461A1

Abstract

A method and device for identifying an angle on an eye of a patient. A method for identifying, on an eye of a patient, an operating angle measured in an angular reference mark (60) formed of the centre of the eye and a horizontal axis passing through the centre of the eye, said axis being within a horizontal plane (xt, yt) of a reference mark of a predefined terrestrial reference frame (xt, yt, zt), consists of: forming an optical image of the eye on a planar sensitive surface (26) of a digital sensor (20), said sensor being provided with a reference mark (x, y, z) comprising first and second axes (x, y) of said sensitive surface (26); acquiring a digital image of the optical image of the eye formed on said sensitive surface (26), said image being provided with a reference mark consisting of first and second axes corresponding respectively to said first and second axes of the reference mark of the digital sensor; during the acquisition of the digital image of the eye, measuring the rotation of the reference mark (x, y, z) of the digital sensor (20) relative to the reference mark (xt, yt, zt) of the terrestrial reference frame; defining a tilt angle (H) defined between the first axis (x) of the reference mark of the digital sensor (20) and the intersection of the horizontal plane (xt, yt) of the reference mark (xt, yt, zt) of the terrestrial reference frame with the sensitive surface (26); determining an angular reference mark (60) in the digital image of the eye, consisting of the digital image of the centre of the eye and an axis angularly separated from the first axis of the reference mark of the digital image by the defined tilt angle (H); transferring the operating angle to the angular reference mark (60) of the digital image; and displaying the digital image of the eye with a mark (62) indicating the transferred operating angle.

Description

METHOD AND DEVICE FOR IDENTIFYING AN ANGLE ON A PATIENT'S EYE

FIELD OF THE INVENTION

The invention relates to the field of ophthalmology, and more particularly to the identification of an operating angle on a patient's eye with a view, in particular, of an astigmatism correction operation by the implantation of a intraocular lens.

STATE OF THE ART

As is known per se, the corneal astigmatism of a patient's eye can be corrected by determining the curvature of the cornea of the eye, and implanting in the cornea a toric lens whose curvature is complementary from that of the cornea, so as to generate an astigmatism opposite to that of the cornea. By aligning the curvature of the lens with that of the cornea, the astigmatism of the lens then compensates for that of the cornea so that the overall optical system formed of the eye and the lens is devoid of astigmatism. The quality of the correction of astigmatism by a toric implant therefore depends essentially on the accuracy of alignment of the lens in the cornea.

Usually, lens positioning in the cornea consists of aligning a meridian of the cornea, namely a straight line on the surface of the cornea passing through the center of the eye, hereinafter "alignment meridian", generally the the most powerful meridian of the cornea, with a corresponding meridian of the lens, namely the least powerful meridian of the latter. The implantation of the toric lens then consists of:

at. locate the alignment meridian on the cornea beforehand. For example, the alignment meridian is marked with two marked points on the cornea, the meridian corresponding to the straight line passing through these two points;

b. make an incision in the cornea;

vs. to penetrate the lens by the incision made;

d. then to align the meridian of the lens, marked with marks and / or remarkable elements of the lens, with the alignment meridian marked on the cornea.

The quality of the correction of astigmatism therefore depends on the quality of alignment of the meridians of the cornea and the lens. It is thus observed that an angular difference between these meridians induces a residual astigmatism which increases very rapidly as a function of this angular difference. In particular, as shown in the document "Surgical correction of astigmatism cataract surgery, by Phillip J. Buckhurst et al., Clin Exp, Optom 2010, 93: 6; 409-418, an angular difference of 10 ° between said meridians induced after the operation a residual astigmatism of about 30% and an angular difference of 15 ° induces a residual astigmatism close to 50%.

A difficulty encountered in the correction of astigmatism by implantation of toric lens comes from the fact that the diagnosis of astigmatism, including in particular the keratometric examination to determine curvature, and hence identify the alignment meridian, is remote in the time of the surgical operation itself. Indeed, once the diagnosis is made, it is necessary to manufacture the lens, which can take time. In addition, the diagnosis can be made in an ophthalmology clinic remote from the operating theater, or even performed by a doctor other than the surgeon in charge of the operation, and there can be a waiting list to undergo a correction operation. astigmatism. There is therefore generally a significant delay between the diagnosis and the operation.

As it is not possible to use a permanent marking of the eye, any mark of the eye that would be made during diagnosis to mark the alignment meridian would have disappeared the day of the operation. In fact, it is advisable, the same day of the operation to locate the alignment meridian according to the information provided by the diagnosis. To do this :

at. the diagnosis consists in locating the angular position of the alignment meridian with respect to a horizontal reference axis, or "0-180 °" axis; and

b. a preoperative step, performed shortly before the operation, consists in locating on the cornea the reference horizontal axis and marking it with two points on the cornea by means of a marker. This marking must be done when the patient is sitting or standing, because once the patient lying down, a natural phenomenon of cyclo torsion changes the position of the meridians. The eye turns indeed in a random and unpredictable way.

During the surgical procedure, the patient is lying down and the surgeon measures the angular position of the alignment meridian using a Mendez ring-type protractor aligned on the horizontal axis marked on the cornea, and affixes on the cornea two marks using a marker so as to locate the alignment meridian. The surgeon then proceeds to the operation itself based on the two marks identifying the alignment meridian. In a preferred manner, the alignment meridian is located during the operation itself by means of an improved optical device based on a microscope, for example a "Callisto" type system from Zeiss GmbH. This type of system makes it possible to locate the two marks identifying the horizontal axis of reference and to automatically locate the angular position of the meridian with respect to the reference axis as a function of an angle value entered into the system. The surgeon then sees in the microscope an image of the eye on which is superimposed an image of the meridian and practice the operation by means of the microscope.

Whatever the technique used to locate the alignment meridian, it is observed that the accuracy of this identification depends significantly on the positioning accuracy of the reference axis. A positioning error of this axis indeed implies a misalignment of the alignment meridian.

However, the location of the horizontal reference axis on the patient's eye is usually performed in a coarse manner. During the preoperative step, the surgeon indeed uses a bubble marker or a pendulum marker, comprising two marker tips aligned parallel to the axis of a spirit level or aligned perpendicularly to the axis of a pendulum. The surgeon then places the two tips of the marker on the cornea so as to have the spirit level in a horizontal position or the pendulum in a vertical position, then strongly presses on the marker so as to affix two marks on the cornea locating the horizontal reference axis.

It is easy to conceive the lack of precision inherent in this type of identification since it is in the judgment that the surgeon considers that the position of the bubble of the spirit level corresponds to the horizon or that the position of the pendulum is vertical. It can thus be seen that the positioning accuracy of the reference axis with this technique is of the order of ten degrees, the reference axis being able to be separated from a truly horizontal axis by an angle up to at 15 °. In addition, an additional source of inaccuracy comes from the coarseness of the marks made by the marker since the thickness of the line is an additional margin of error. Indeed, to be effective, it is necessary to strongly support the patient's cornea so as to obtain visible marks. In doing so, the marks "drool", and are thick. This may result in misalignment of the alignment meridian inducing residual astigmatism of 50%. It can thus be seen that the accuracy of the correction of astigmatism depends for a large part on the surgeon's know-how in the use of the state of the art bubble or pendulum markers when locating the reference axis. . In addition, strong support of the marker on the cornea can cause pain and / or trauma to the patient.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method and a device for accurately identifying an angle of view of a patient's eye with respect to a horizontal reference axis.

For this purpose, the subject of the invention is a method of identifying, on an eye of a patient, an operating angle measured in an angular reference mark formed by the center of the eye and a horizontal axis passing through the center of the eye. the eye, said axis being included in a horizontal plane of a predetermined terrestrial reference frame, the method consisting of:

^■ forming an optical eye image on a planar sensitive surface of a digital sensor, said sensor being provided with a marker comprising first and second axes of said sensitive surface;

^■ acquiring a digital image of the optical image of the eye formed on said sensitive surface, said image being provided with a marker consisting of a first and second axes respectively corresponding to said first and second axes of the sensor mark digital;

^■ when acquiring the digital image of the eye, measure the rotation of the reference of the digital sensor with respect to the reference of the terrestrial reference;

^■ determining an angle of inclination defined between the first axis of the reference of the digital sensor and the intersection of the horizontal plane of the terrestrial reference frame with the sensitive surface;

^■ determine an angular reference in the digital image of the eye, consisting of the digital image of the center of the eye and an axis angularly separated from the first axis of the reference of the digital image by the angle of determined inclination;

^■ transfer the operating angle to the angular reference of the digital image; and

^■ display the digital image of the eye with a mark identifying the operating angle reported.

In other words, the method makes it possible to know the position of an image of the eye, formed on a sensitive surface, with respect to the terrestrial reference, and thus to determine in a precise manner the position of a horizontal plane relative to at said sensitive surface. Such a measurement of horizontality, for example carried out using an inertial unit of the state of the art, makes it possible to identify on a digital image the position of the reference axis with a precision of the order of 1 °. The practitioner thus has in view of its preparation of the surgical operation an image, for example displayed on a screen or displayed by printing on paper, on which the alignment meridian is accurately located. The image obtained by the method can also be communicated to a microscope-based system of the state of the art, said system then directly having the position of the alignment meridian without having to rely on marks made at the same time. bubble marker or pendulum marker.

According to a particular embodiment, the method further comprises the steps of:

^■ identify, in the digital image of the eye, a remarkable element;

^■ measure the angle of the remarkable element in the angular reference of the digital image;

^■ form the sum of the operating angle and the angle of the remarkable element;

^■ display said sum together with the digital image of the eye;

More particularly, the method also comprises the steps of:

^■ identify directly to the patient the remarkable element identified in the digital image of the eye; and

^■ identify the operative angular position by reporting said sum with respect to the axis passing through identified remarkable element and the center of the eye.

In other words, to effectively locate the position of the alignment meridian on the patient's cornea, it is sufficient for the practitioner to make an arbitrary mark on the eye or to locate a remarkable element of the eye, such as a vessel for example, that is to say to choose an arbitrary reference axis requiring no positioning accuracy. To mark the position of the alignment meridian on the cornea, it is enough for him to postpone the sum of the angles from the arbitrary mark.

Advantageously, the measurement of the angle of rotation between the reference of the digital sensor and the terrestrial reference is carried out by means of an inertial unit. More particularly, the measurement of the angle of rotation between the reference mark of the digital sensor and the terrestrial reference system comprises a measurement of the angular velocity of the digital sensor in the reference of the digital sensor, a measurement of the magnetic field in which the digital sensor is immersed in the reference of the digital sensor and the fusion of the measurements so as to obtain the position of the horizontal plane in the reference of the digital sensor.

The invention also relates to an identification device on a patient's eye of an operating angle measured in an angular reference mark formed by the center of the eye and a horizontal axis passing through the center of the eye, said axis being included in a horizontal plane of a predetermined terrestrial reference, the device comprising:

^■ a digital photography apparatus comprising a digital sensor having a planar sensitive surface, said sensor being capable of acquiring a digital image of the patient's eye;

^■ an interface for entering a value for the operating angle;

^■ a display adapted to display the digital image of the patient's eye; and

^■ an information processing unit connected to the photographing apparatus, to the input and display interface, the unit being adapted to defer operating angle on a digital image of a patient's eye acquired by the digital photography apparatus and controlling the screen for displaying therein the digital image of the eye and a mark on said image identifying the operating angle reported.

According to the invention:

^■ the device comprises a unit of angular measure, connected to the information processing unit, adapted to measure a tilt angle defined between a predetermined axis of the sensitive surface and the intersection of the horizontal plane of the terrestrial reference frame of reference with the sensitive surface;

^■ the information processing unit is adapted:

o determining an angular reference in the digital image of the eye, consisting of the image of the center of the eye and an axis angularly separated from an axis of the digital image, corresponding to the axis of the sensitive surface, by the determined angle of inclination;

o to postpone the operating angle in the angular reference of the digital image; o to control the screen to display on it the digital image of the eye with a mark identifying the operating angle reported

According to one embodiment:

^■ the device further comprises means for identifying a remarkable feature in the digital image of the eye, connected to the information processing unit; and

^■ the information processing unit is adapted:

o measuring the angle of the remarkable element in the angular reference of the digital image of the eye;

o to form the sum of the operating angle and the angle of the remarkable element; and

o to control the screen to display on this one said sum together with the digital image of the eye. Advantageously, the means for identifying the remarkable element comprise a touch screen capable of displaying the digital image of the eye, and able to identify therein an element corresponding to a point of contact on the screen.

Advantageously, the device is a smart phone, or "smartphone", or is a touch pad.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the accompanying drawings, in which:

^■ Figure 1 is a schematic exploded view of a device according to the invention illustrating components forming part of the invention; and

^■ Figures 2 is a schematic view of a fixed reference point of the device and a landmark;

^■ Figure 3 is a schematic view illustrating the position of the horizon on a sensitive surface of a digital sensor forming part of the device according to the invention;

^■ Figure 4 is a flowchart of a method according to the invention implemented by the device of Figure 1;

^■ Figure 5 is a screen shot of an image produced by the process according to the invention;

^■ Figure 6 is a schematic view of a shot by the device according to the invention; and

^■ Figure 7 is a flowchart of a preferred embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

In Figure 1, a smarthpone 10 includes a rear cover 12, an electronic circuitry 16 and a front cover 14, forming with the rear cover 12 a housing for the circuits 14. The cover 12 includes a camera lens 18 and the front cover comprises a touch screen 21. The circuits 14 comprise a digital photographic sensor 20 arranged opposite the objective 18, an inertial unit 22 and an information processing unit 24 connected to the digital sensor 20, to the central unit inertial 22 and the touch screen 21 to exchange data therewith. As is known per se, the touch screen 21 is able to display digital images acquired by the digital sensor 20 and also serves as a human-machine interface with a user who uses the screen to enter data into the computer. smartphones 10, including alpha-numeric data.

The digital sensor 20 comprises a flat sensitive surface 26 arranged in the focal plane of the objective 18 when the smartphone 10 is assembled and delivers, on the control of a user by means of, for example, the touch screen 21, digital images of the scene projected on the sensitive surface 26 by the objective 18. Advantageously, when the digital sensor 20 is activated, it delivers a continuous stream of images to the information processing unit 24 which controls back the screen 21 for it to display said stream. The user then orders the smarphone 10 to choose which image of the stream displayed on the screen 21 he wishes to keep, as is known per se.

The inertial unit 22 comprises for its part at least two sensors, and preferably three sensors, among a triaxial accelerometer measuring the acceleration of the smarthpone 10 around three axes x, y, z of an orthogonal reference (x, y, z) fixed linked to the smarthpone, a tri-axis gyrometer measuring the angular velocity of the smartphone 10 around said axes and a tri-axis magnetic sensor measuring the components of a magnetic field bathing the smartphone 10 in said marker. The orientation of the sensitive surface 26 in the (x, y, z) reponse is fixed and known, the sensitive surface 26 being for example parallel to the plane defined by the x, y axes of the (x, y, z) coordinate of the smartphone 10. The sensitive surface 26 is then identified by the axes (x, y) or any other reference whose position is known in the reference formed by the axes (x, y).

Corollary, a digital image acquired by the sensor 20 corresponding to a spatial discretization of the sensitive surface 26, the processing unit 24 thus knows the position of the horizon in a digital image acquired by the sensor 20. Similarly, the digital image is associated with a reference (x, y) corresponding to that of the sensitive surface 26.

The measurements of the central unit 22 are delivered to the information processing unit 24 which determines, in a manner known per se, the rotation of the marker (x, y, z) of the smartphone 10 with respect to an orthogonal reference mark of the terrestrial reference (xt, yt, zt) illustrated in FIG. 2, for example the North-East-Low inertial reference mark, or NED (North-East-Down) reference, defined from a horizontal plane (xt , yt) tangent to the surface of the earth and whose vectors xt, yt, zt coincide respectively with the North, East and gravity directions. As illustrated in FIG. 3, the information processing unit 24 therefore knows at each instant the position of the horizontal plane of the terrestrial reference (xt, yt) with respect to the plane (x, y) of the smartphone 10 defined by the vectors x and y of the reference (x, y, z). The unit 24 therefore knows the position of the horizon on the sensitive surface 26, defined as the intersection of the plane (xt, yt) with the plane (x, y). Thus, the processing unit 24 knows the position of the horizon in the plane of the sensitive surface 26, illustrated in FIG. 3 by the axis "0-180 °", and identified by the angle Θ _Η relative to for example, to the x-axis of the sensitive surface 26, or "angle of inclination".

Finally, the smartphone 10 comprises in a computer memory, for example a mass memory, a computer application, executable on command of the user by the information processing unit 24, allowing the identification of an operating angle such as as described below, hereinafter "application".

It will now be described with reference to FIGS. 4 to 6, a method for identifying an operating angle on a patient's eye implemented by the device just described, in particular the identification of the patient. angle that forms an alignment meridian for the implantation of a toric lens of astigmatism correction of the eye. The method is advantageously implemented during a pre-operative stage in order to provide the surgeon with an image helping him, during the operation itself, to locate the alignment meridian on the patient's eye.

The method begins, at 40, with the launch of the application by the user of the smartphone 10. The application then commands the display, on the touch screen 21, of an entry request of the angle that the alignment meridian should do with the horizontal axis passing through the center of the eye, and optionally personal data about the patient. Once this information has been entered by the user of the smartphone 10, for example by means of the touch screen 21, the application invites, at 44, the user to take a photograph of the patient's eye.

In parallel, the application retrieves the measurements from the central unit 22 to determine the position of the horizon on the sensitive surface 26, for example by identifying the angle of inclination Θ _Η , OR uses an application running on the smartphone 10 already performing this function, and controls the display of the image flow produced by the digital sensor 20 on the screen 21 with the position of the horizon in the stream of images. Advantageously, the application also shows on the touch screen a representation of a Mendez ring 60 in superposition of the displayed image flow, the axis 0-180 ° axis of the image of the Mendez ring being aligned on a horizontal axis (Figure 5).

The user then places the objective 18 in front of the patient's eye (FIG. 6) so as to form an image of the eye on the sensitive surface 28 through the objective 18. The user then selects a image of the eye in the stream displayed by the screen 21.

At 46, the application controls the storage of the digital image selected by the user as well as the value of the tilt angle Θ _Η of the selected image. The application further controls the screen 21 so as to freeze the stream of images on the selected image. In a next step 48, the application locates the operating angle in the selected digital image using an angular mark of the image. For example, as illustrated in FIG. 5, the angular reference is represented by the image of the Mendez ring 60, whose reference axis "000-180 °" is aligned on a horizontal axis, namely an axis having an angle with respect to the x axis equal to the tilt angle Θ _Η stored, and whose center is positioned on the image of the center of the eye.

The positioning of the ring 60 is for example made by the user during the shooting. Advantageously, the application allows the user to zoom the image of the eye displayed on the screen so as to match the image of the pupil or iris of the eye, circular in nature, with a concentric circle to the ring 60, so as to position the ring 60 on the center of the eye. In a variant, the application comprises an alignment module that realizes the positioning of the ring 60 on the image of the center of the eye automatically, in a manner known per se.

The application then reports, at 50, the operating angle in the angular reference, in the example illustrated in FIG. 5 at an angle equal to 27 °, and marks the operating angle in the digital image of the eye, for example by means of an arrow 62. There is thus obtained a final digital image comprising the digital image of the eye and a mark accurately identifying the position of the alignment meridian.

Advantageously, the method also includes the identification of the operating angle by a remarkable element of the eye. Indeed, the mark identifying the position of the alignment meridian may be positioned in the image without there being on it, or in the immediate vicinity thereof, a remarkable element, for example a blood vessel, a wrinkle or a particular pattern of the iris, easily recognizable by the surgeon, which would easily locate directly on the eye the position of the meridian Referring to Figure 7, advantageously, the method further comprises selecting, at 52, a remarkable element of the eye by the user of the smartphone 10 by means of the touch screen. For example, the user locates in the selected digital image a blood vessel, a wrinkle, a particular pattern of the iris, or any easily identifiable element, or even a mark 64 made directly on the eye arbitrarily at using a marker. The user then selects the remarkable item by pressing the touch screen 21, for example using a stylus, or by moving a cursor on the screen and validating the position of said cursor. Likewise, a zoom function of the displayed image can be used to select the remarkable item.

Advantageously, the digital sensor 20 has a high definition making it easy to detect a remarkable end of the eye element. In particular, the digital sensor 20 comprises more than eight million pixels. Similarly, the objective 18 may be chosen so that the optical image of the eye occupies most of the sensitive surface 26 of the digital sensor 20.

The application then determines, at 54, the coordinates of this element in the digital image of the eye displayed on the screen, and then determines in the angular frame of the image, the angular position of the selected remarkable element. Advantageously, the application calculates or measures the angular difference Θ between the remarkable element and the position of the alignment meridian, for example by summing the operating angle and the angle of said element in the angular reference. In 56, the application then superimposes the value of this difference with the image of the eye and the mark of the position of the alignment meridian.

The surgeon can then simply mark on the patient's eye, including his cornea, the position of the alignment meridian, locate the remarkable element, by placing a Mendez ring on the cornea by aligning it on said element, and by reporting the angular difference displayed.

Alternatively, the final image generated by the application may be communicated to a more complex ophthalmic system used by the surgeon during the operation. The alignment meridian is directly marked on the image communicated to said system, it is therefore no longer necessary to measure the horizontal axis passing through the center of the eye to locate the position of the meridian. The invention has been described in the context of a smartphone. Of course, this applies to any type of computer system provided with a digital camera device type device and a device for measuring the horizontality of the camera, such as a touch pad equipped with such elements, or a camera equipped with an inertial unit and connected to a personal computer.

Claims

1. A method for identifying in an eye of a patient an operating angle measured in an angular reference (60) formed by the center of the eye and a horizontal axis passing through the center of the eye, said axis being comprised in a horizontal plane (xt, yt) of a reference of a predetermined terrestrial reference (xt, yt, zt), the method comprising:

^■ forming an optical image of the eye on a planar sensitive surface (26) of a digital sensor (20), said sensor being provided with a coordinate system (x, y, z) having first and second axes (x y) of said sensitive surface (26);

^■ acquiring a digital image of the optical image of the eye formed on said sensitive surface (26), said image being provided with a marker consisting of a first and second axes respectively corresponding to said first and second axes of digital sensor landmark;

^■ when acquiring the digital image of the eye, measuring the rotation of the coordinate system (x, y, z) of the digital sensor (20) relative to the reference (xt, yt, zt) of the terrestrial reference system;

^■ determining an angle of inclination (ΘΗ) defined between the first axis (x) of the reference of the digital sensor (20) and the intersection of the horizontal plane (xt, yt) of the reference (xt, yt, zt) of the terrestrial reference system with the sensitive surface (26);

^■ determining an angular mark (60) in the digital image of the eye, consisting of digital image of the center of the eye and an axis angularly separated from the first axis of the digital image coordinate by determined angle of inclination (ΘΗ);

^■ transfer the operating angle to the angular marker (60) of the digital image; and

^■ display the digital image of the eye with a mark (62) identifying the operating angle reported.

The method of claim 1, further comprising steps of:

^■ identifying in the digital image of the eye, a remarkable member (64);

^■ measuring the angle of the remarkable element in the angular reference (60) of the digital image;

^■ form the sum (Θ) of the operating angle and the angle of the remarkable element;

^■ display said sum (Θ) together with the digital image of the eye;

The method of claim 2, further comprising the steps of:

4. The method of claim 1, 2 or 3, wherein the measurement of the angle of rotation between the reference of the digital sensor and the terrestrial reference is performed by means of an inertial unit.

5. The method of claim 4, wherein the measurement of the angle of rotation between the reference of the digital sensor and the terrestrial reference comprises a measurement of the angular velocity of the digital sensor in the reference of the digital sensor, a measurement of magnetic field in which is bathed the digital sensor in the reference of the digital sensor and the merging of the measurements so as to obtain the position of the horizontal plane in the reference of the digital sensor.

6. Device (10) for identifying on a patient's eye an operating angle measured in an angular reference mark formed by the center of the eye and a horizontal axis passing through the center of the eye, said axis being understood in a horizontal plane (xt, yt) of a reference (xt, yt, zt) of a predetermined terrestrial reference, the device comprising:

^■ a digital photographing apparatus (18, 20) comprising a digital sensor (20) having a planar sensitive surface (26), said sensor being capable of acquiring a digital image of the patient's eye;

^■ an interface (21) for inputting a value for the operating angle;

^■ a screen (21) adapted to display the digital image of the patient's eye; and

^■ a processing unit of information (24), connected to the photographing apparatus (18, 20) to the input interface and the screen (21), said unit (24) being adapted to defer operating angle on a digital image of a patient's eye acquired by the digital photography apparatus (18, 20) and controlling the screen (21) for display therewith of the digital image of the digital camera eye and a mark (62) on said image identifying the operating angle reported, characterized:

^■ in that the device comprises an angular measuring unit (22, 24), connected to the information processing unit (24) adapted to measure an angle of inclination (ΘΗ) defined between a predetermined axis (x ) the sensitive surface (26) and the intersection of the horizontal plane (xt, yt) of the reference frame of the terrestrial frame with the sensitive surface (26); ^■ and in that the information processing unit (24) is adapted:

o determining an angular reference (60) in the digital image of the eye, consisting of the image of the center of the eye and an axis angularly separated from an axis of the digital image, corresponding to the the axis of the sensitive surface, by the determined angle of inclination; (ΘΗ)

o to postpone the operating angle in the angular reference (60) of the digital image;

o to control the screen (21) to display on it the digital image of the eye with a mark (62) identifying the operating angle reported

7. Device according to claim 6, characterized

^■ in that it further comprises means for identifying a remarkable element (64) in the digital image of the eye, connected to the information processing unit (24); and

^■ in that the information processing unit (24) is adapted:

o measuring the angle of the remarkable element (64) in the angular coordinate system (60) of the digital image of the eye;

o forming the sum (Θ) of the operating angle and the angle of the remarkable element; and

o controlling the screen (21) to display thereon said sum (Θ) together with the digital image of the eye.

8. Device according to claim 7, characterized in that the means for identifying the remarkable element comprises a touch screen (21) adapted to display the digital image of the eye, and able to identify therein a corresponding element at a point of contact on the screen.

9. Device according to any one of claims 6 to 8, characterized in that the device is a smartphone or a touch pad.