GLAUCOMATOUS DISEASE

Background of the Invention

Field of the Invention

The present invention generally relates to a method and a system for automatically classifying the degree of optic nerve glaucomatous disease (hereinafter, briefly also referred to as "glaucomatous damage") in human subjects.

Description of the related art

Glaucoma is an ocular disease characterized by an increase of the intraocular tension. The intraocular hypertension causes objective symptoms, such as an increasing in the eyeball and an excavation of the optic papilla, and subjective symptoms, such as visual disturbances which also can cause blindness and possible pain.

It is desirable to define a standard methodology for classifying and analyzing the degree of optic nerve glaucomatous damage.

Particularly, a standard methodology for classifying and analyzing the degree of glaucomatous damage of optic nerve and nerve fibers would be extremely useful for those who, at the research level, undertake studies on the effectiveness of antiglaucoma drugs and face problems relating to selection of clinical cases to be inserted in experimental research programs, and would provide an instrument to clearly and immediately evaluate the gravity and the typology of the damage, both by the attending doctor, for example for the prescription of operations aimed at the specific problem, and by the patient him/herself.

Different methods for classifying glaucomatous damage have been studied and proposed, which for the most part exploits data obtained from the so-called "Computerized Automated Perimetry" (CAP).

In the CAP method, the patient is subjected to a perimetry examination which allows to define the perceptive level of the patient within the visual field (differential light sensitivity) by means of light stimuli which are uniformly spread within a substantially circular area. The higher or lower sensibility in the perception of the light stimulus allows to formulate a diagnosis on the presence or absence of a glaucomatous damage, and on the gravity thereof. From the numeric data obtained by means of the perimetry examination, perimetry indexes are mathematically extrapolated, which allow to formulate an approximated evaluation of the gravity and distribution damage. The most important perimetry indexes obtainable by means of CAP are the "MD" ("Mean defect or Mean deviation") index, which provides information about the global or general level of the visual sensitivity loss, and the "CLV" ("Corrected Loss Variance") index, or its square root "CPSD" ("Corrected Pattern Standard Deviation"), which provide information about the non homogeneity of defects in the visual field.

A glaucomatous damage classification method is known, which, starting from the results of the perimetry exam, exploits the isopters or the gray scale for graphically depicting the visual sensitivity level of the patient.

The "Esterman grids" method is also known, which provides for subdividing the visual field in 100 areas, each one depicting a 1% thereof, which have different sizes based on their different functional values and based on the requested evaluation sensitivity.

A further classification method, which employs the accumulation curve of the visual field defect known as "Bebie curve", allows to define a plurality of glaucomatous damage gravity classes based on the position of the individual curve on a graphic.

Further classification methods exists, based on probability maps of the "Statpac Humprey" program.

In the Italian patent application UD95A000007 filed on 23/01/1995, it is described a standardized system (and a corresponding device) for classifying and staging defects of the visual field caused by glaucomatous damage, adapted to classify the glaucomatous damage starting from at least two perimetry indexes obtained by means of a CAP examination. The first perimetry index, specifically, the MD, provides an indication of the global or general damage, while the second perimetry index, particularly the CPSD (or the CLV), provides an indication about the visual field damage spatial distribution. The classification system provides to arrange a diagram having at least two coordinates: the

MD index values are located on a first coordinate, the CPSD (or CLV) index values are located on the second coordinate. The diagram is subdivided by a grid adapted to define a plurality of contiguous classes based on the gravity and type of the observed glaucomatous damage. The positioning of the specific glaucomatous damage as defined by the crossing between the values of the two perimetry indexes provided in the diagram within a specific class allows an immediate and precise definition of the gravity level and of the more or less accentuated localization degree of the damage itself.

In more recent years, a non invasive image diagnostic technique has been developed, known as "Optical coherence tomography" ("OCT"), and in particular the so- called "Fourier-Domain OCT" or "Spectral-Domain OCT" ("SD-OCT") which has proven to be a valid aid in the glaucoma diagnosis. The OCT allows to reveal retinal layers by observing the interference schemes of laser light, and particularly the fibers layer of the optic nerve ("Retinal Nerve Fiber Layer" or "RNFL"), relevant in the glaucomatous pathologies since it has been found that in such circumstances the layer of the optic nerve fibers is subjected to a thinning.

Summary of the invention

The Applicant has observed the following.

Several of the classification methods proposed in the last years have been proved not to be capable of creating a standard and universally accepted methodology capable of providing an analysis instrument which is common, simple and at the same time that is reliable, both at research level and for the common clinic practice.

The method that uses the isopters, which can be considered as a graphic translation of the numeric tables, even if it is simple and capable of providing an immediate indication about the type and the localization of the visual field defects of a patient, it is subjective and results to be very imprecise since it is exclusively based on the personal experience of the one that adopt it.

Also the "Esterman grids" method provides a qualitative evaluation, and not quantitative, of the defect, and can be used only with manual kinetic strategies, or with supraliminal static strategies, which are of a little utility in the glaucomatous visual field study.

The method which employs the "Bebie curve", even if rather effective since allows to both recognize the gravity of the visual field defect and to differentiate the various types thereof, it is not capable of reuniting in uniform and standard classes all the possible alterations of the visual field without employing schemes that are very complex and that cannot be easily and immediately read.

The further classification methods, based on probability maps of the "Statpac Humphrey" program, are complex and not practical.

The system described in the Italian patent application UD95A000007, even if effective, may have its results invalidated by a series of artifacts, due to the subjectivity of the visual field exam. Moreover, such a system does not take into consideration relevant factors such as for example the race of the patient. A further limitation of this system is represented by the lacking of information on the localization of the perimetry defects. Finally, important discrepancies may arise between visual field defects and optic nerve damage.

Furthermore, according to the Applicant, methods for automatically classifying and staging glaucomatous damage based on information obtainable by means of the SD- OCT have not been proposed.

The Applicant has faced the problem of making available a method (and a corresponding system for implementing the method itself) for the automatic, objective and not subjective, classification of the glaucomatous disease degree of a patient, which is capable of aiding medical researchers for the formulation of the diagnosis and of the choice of the healing operation to be carried out on the patient.

According to an aspect of the present invention, a method for classifying defects of the nerve fibers layer originating from glaucomatous damage is provided.

According to an embodiment of the present invention, the method is carried out under the control of a system comprising a programmable data processor.

The method comprises:

- receiving a pair of values comprising a first value of a first parameter relating to the measure of the thickness of the fiber layer of the optic nerve of the higher quadrant of a subject, and a second value of a second parameter relating to the measure of the thickness of the fiber layer of the optic nerve of the lower quadrant of the subject;

- providing a definition of a reference structure comprising a plurality of sets of pairs of predetermined values, each of said sets of pairs of predetermined values corresponding to a respective gravity and localization class of glaucomatous damage;

- identifying which set of pairs of predetermined values of the reference structure said received pair of values belongs to;

- determining the gravity and localization class of glaucomatous damage of the subject based on the identified set of pair of values said received pair of values belongs to.

According to an embodiment of the present invention, said receiving a pair of values comprises memorizing an indication of said pair of values in a memory of the system.

According to an embodiment of the present invention, said identifying which set of pairs of predetermined values of the reference structure said received pair of values belongs to comprises comparing the memorized pair of values with said definition of the retrieved reference structure.

According to an embodiment of the present invention, said determining the gravity and localization class of glaucomatous damage of the subject based on the identified set of pair of values said received pair of values belongs to comprises determining the gravity and localization class of glaucomatous damage of the subject based on the identified set of pair of values said memorized pair of values belongs to.

According to an embodiment of the present invention, said identifying which set of pairs of predetermined values of the reference structure said received pair of values belongs to comprises:

- retrieving said definition of the reference structure from a database;

- comparing the received pair of values with said definition of the retrieved reference structure.

Said determining comprises displaying on a display device an indication of the gravity and localization class of glaucomatous damage of the subject based on said comparison.

According to an embodiment of the present invention, said identifying which set of pairs of predetermined values of the reference structure said received pair of values belongs to comprises: - retrieving said definition of the reference structure from a database;

- displaying on a display device a two-dimensional diagram having at least two coordinates, each coordinate corresponding to a respective parameter between said first parameter and said second parameter, said two-dimensional diagram representing the definition of said reference structure, the plane of said two-dimensional diagram being subdivided in a plurality of areas, each of said areas corresponding to a respective set of pair of predetermined values of said sets of pairs of predetermined values of the reference structure;

- displaying on the two-dimensional diagram a graphic representation of the point having said received pair of values as coordinates. Said determining comprises determining the gravity and localization class based on said displaying of the graphic representation of the point.

According to an embodiment of the present invention, said identifying which set of pairs of predetermined values of the reference structure said received pair of values belongs to comprises: - providing a display support which represents a two-dimensional diagram having at least two coordinates, each coordinate corresponding to a respective parameter between said first parameter and said second parameter, said two-dimensional diagram representing the definition of said reference structure, the plane of said two-dimensional diagram being subdivided in a plurality of areas, each of said areas corresponding to a respective set of pairs of predetermined values of said sets of pairs of predetermined values of the reference structure;

- individuating on each of said coordinates a respective value between said first value of the first parameter and said second value of the second parameter of said pair of values; - identifying within said plane the position of the point univocally defined by said first value of the first parameter and by said second value of the second parameter, wherein:

- said determining the gravity and localization class of glaucomatous damage of the subject comprises determining in which area of the plane of said plurality of areas said point falls.

According to an embodiment of the present invention, said plurality of set of pairs of predetermined values comprises:

- a first set of pairs of predetermined values corresponding to a normal condition of the subject; - a plurality of second sets of predetermined values corresponding to subsequent gravity stages of the glaucomatous damage of the subject.

According to an embodiment of the present invention, different second sets of pairs of predetermined values corresponding to a same subsequent gravity stage of the glaucomatous damage of the subject correspond to a different respective localization of the glaucomatous damage of the subject. According to an embodiment of the present invention, said providing a definition of the reference structure comprises:

- receiving an indication of at least one among the age of the subject and the race of the subject; - selecting such definition of the reference structure among a plurality of predefined definitions of the reference structure based on said received indication.

According to an embodiment of the present invention, said providing a definition of a reference structure comprises:

- receiving an indication of at least one among the age of the subject and the race of the subject;

- generating such definition of the reference structure by means of mathematical operations based on said received indication.

According to another aspect of the present invention, a computer program is provided, comprising instructions such to implement the previous method when executed by a programmable data processor.

According to another aspect of the present invention, a system is provided for classifying defects of the nerve fibers layer originating from glaucomatous damage. Said system comprises:

- means for receiving a pair of values comprising a first value of a first parameter relating to the measure of the thickness of the fiber layer of the optic nerve of the higher quadrant of a subject, and a second value of a second parameter relating to the measure of the thickness of the fiber layer of the optic nerve of the lower quadrant of the subject;

- means for providing a definition of a reference structure comprising a plurality of sets of pairs of predetermined values, each of said sets of pairs of predetermined values corresponding to a respective gravity and localization class of glaucomatous damage;

- means for identifying which set of pairs of predetermined values of the reference structure said received pair of values belongs to;

- means for determining the gravity and localization class of glaucomatous damage of the subject based on the identified set of values said received pair of values belongs to. According to an embodiment of the present invention, said means for identifying which set of pairs of predetermined values of the reference structure said received pair of values belongs to comprises:

- means for retrieving said definition of the reference structure from a database;

- means for comparing the received pair of values with said definition of the retrieved reference structure, wherein said means for determining comprises:

- means for displaying on a display device an indication of the gravity and localization class of glaucomatous damage of the subject based on said comparison.

According to an embodiment of the present invention, said means for identifying which set of pairs of predetermined values of the reference structure said received pair of values belongs to comprises:

- means for retrieving said definition of the reference structure from a database;

- means for displaying on a display device a two-dimensional diagram having at least two coordinates, each coordinate corresponding to a respective parameter between said first parameter and said second parameter, said two-dimensional diagram representing the definition of said reference structure, the plane of said two-dimensional diagram being subdivided in a plurality of areas, each of said areas corresponding to a respective set of pair of predetermined values of said set of pairs of predetermined values of the reference structure;

- means for displaying on the two-dimensional diagram a graphic representation of the point having said received pair of values as coordinates.

Said means for determining comprises:

- means for determining the gravity and localization class based on said displaying of the graphic representation of the point.

According to another aspect of the present invention, a display support is provided for representing a two-dimensional diagram having at least two coordinates, each coordinate corresponding to a respective parameter between a first parameter relating to the measure of the thickness of the fiber layer of the optic nerve of the higher quadrant, and a second parameter relating to the measure of the thickness of the fiber layer of the optic nerve of the lower quadrant of the subject, the plane of said two-dimensional diagram being subdivided in a plurality of areas, each of said areas corresponding to a respective set of pairs of predetermined values of said first and second parameters, wherein:

- each of said sets of pairs of predetermined values corresponds to a respective gravity and localization class of glaucomatous damage. Thanks to the present invention, a method, a system, a computer program for a programmable data processor, and a display support which allow to automatically classify, in an objective and not subjective way, thus in a reliable and reproducible way, the glaucomatous damage entity. This is very useful for those who operates in the field of researching and experimenting new drugs, as well as for the clinic practice, being a valid aid for the diagnosis and the consequent choice of the most appropriate therapy based on the case.

This method, system, computer program for a programmable data processor and/or display support allow to immediately verify the progression of the glaucomatous pathology (even in the first stages thereof) without having to subject the patient to any invasive examination, since the only examination required is a non invasive examination for obtaining measures of the thickness of the fiber layer of the optic nerve (for example, obtained by means of acquisition instruments of the SD-OTC type).

Brief description of the drawings

These and other features and advantages of the present invention will be made evident by the following description of some exemplary and non- limitative embodiments thereof. The attached drawings will be of help for a better understanding of the embodiments of the invention described in the following, wherein:

Figure 1 shows a diagnostic aid apparatus comprising an automatic classification and staging system of the glaucomatous damage of optic nerve according to an embodiment of the present invention;

Figures 2A and 2B illustrate an operation flux of the main operations carried out during operation by the automatic classification and staging system of Figure 1, according to an embodiment of the present invention;

Figures 3 and 4 shows each a diagram used for automatically classifying the glaucomatous damage, according to an embodiment of the present invention;

Detailed description of exemplary embodiments of the invention

With reference to the attached drawings, Figure 1 schematically shows a diagnostic aid apparatus 100 comprising a system 105 according to an embodiment of the present invention for classifying defects of the nerve fiber layer caused by glaucomatous damage.

The diagnostic apparatus 100 comprises one or more acquisition instruments for acquiring parameters relating to patients, particularly one or more SD-OCT instruments (in the following, simply SD-OCT) 110, 115, also of different brands. Optionally, the acquiring instrument(s) may comprise, in addition to the SD-OCT 110, 115, one or more instruments for the Computerized Automated Perimetry (CAP).

The acquisition instrument(s) 110, 115 are connected to the automatic classification system 105, and provide to the latter input parameters, as described in more detail in the following.

The system 105 comprises a programmable data processor, for example a personal computer, comprising in a known manner a central processing unit (CPU), dynamic memory resources (RAM memory), non-volatile memory resources (ROM, EPROM, EEPROM, Flash EPROM memories), mass memory unit such as hard disk and/or solid state disk and/or optical disk units, man-machine interface comprising data input means such as a keyboard 120 and a pointing device (mouse, touchpad and similar devices, not illustrated in figures) and data output means such as a display device 125 (monitor, display, and similar devices), communication ports (for example USB ports), network interface cards, such as an Ethernet card for the connection to a computer network, and particularly for the connection to an Intranet network or to the Internet.

The system 105 is capable of carrying out computer programs (applications), which may be installed in the system 105, for example by means of CD-ROM, DVD- ROM, or directly from the computer network the system 105 is connected to.

Particularly, the system 105 is programmable for carrying out a program adapted to implement a method according to the present invention.

Making reference to the operation flux of Figures 2A and 2B, during operation, the system 105 provides the user (through the display device 125) with dialogue windows having areas addressed to data introduction by the user itself.

Particularly, the system 105 preferably provides the user (through the display device 125) with a dialogue window through which the user is requested to introduce personal data of a patient, such as the name e the date of birth (block 205).

Based on the introduced personal data, the system 105 calculates the patient age (block 210).

The system 105 further provides the user (for example through the display device 125) a dialogue window through which the user is requested to select the race, i.e., the ethnic group, of the patient (block 215). The choice is preferably driven, providing the user, for example through a pull down menu, a list of (main) predefined ethnic groups (for example, Caucasian, Asian, Afro-American, Indian). Preferably, a default race is predefined n the system 105, for example the Caucasian one.

The age of the patient, and his/her belonging to a particular ethnic group, influence the values of the parameters measured by the acquisition instruments, and therefore it is advantageous to be taken into account.

Advantageously, the system 105 may provide the user (through the display device 125) with a dialogue window through which the user may select which one among the acquisition instruments connected to the system 105, for example which one of the SD- OCT 110, 115 connected to the system is intended to be used (block 220). Preferably, a default acquisition instrument is preset in the system 105.

Then, the system 105 retrieves the parameters based on the instrument 110, 115 and based on the ethnic group selected by the operator (block 225), as already described in the following.

A SD-OCT is capable of providing a measure of the thickness of the nerve fibers composing the optic nerve of a patient, in form of various parameters. According to the present invention, the system 105 obtains (block 230) from the selected SD-OCT 110, 115 two parameters which represent the average of the R FL thickness of the higher quadrant and of the lower quadrant, respectively ("Higher quadrant thickness average" and "Lower quadrant thickness average"). These two parameters are directly influenced by the glaucomatous damage.

The system 105 then verifies whether the received input data are completed (decisional block 235), for example whether the age of the patient has been selected and/or whether the type of SD-OCT to be used has been selected: in the negative case (exit branch NO of decisional block 235), the flow of operation returns back to the beginning, while in the affirmative case, the operation proceed with the selection of a two-dimensional diagram (for example a two-dimensional Cartesian diagram) in which the axis of one of the two coordinates, for example the abscissa axis, reports values that can be assumed by one of said parameters ("Higher quadrant thickness average" or "Lower quadrant thickness average") obtainable from the SD-OCT, for example the parameter average of the R FL thickness of the higher quadrant, and the other axis, for example the ordinate axis, reports values that can be assumed by the other one of said parameters obtainable from the SD-OCT, for example the parameter average of the RNFL thickness of the lower quadrant (block 240). As will be described in details in the following of the present description, the selected diagram is preferably based on the previously specified age and/or race of the patient, and/or based on the acquisition instrument 110, 115 type that has been used.

At this point, such diagram is displayed (block 245) to the user on the displaying device 125. A first example of diagram that is displayed to the user is illustrated in Figure 3.

In the considered example, the values of the parameter "average of the RNFL thickness of the higher quadrant" are reported on the abscissa axis with a decreasing trend from left to right, from a maximum value of average thickness, in the example, 120 μιη, to a minimum value of average thickness, in the example 40 μιη. The values of the parameter "average of the RNFL thickness of the lower quadrant" are reported on the ordinate axis with an increasing trend from the bottom to the top, from a minimum value of average thickness, in the example, 40 μιη, to a maximum value of average thickness, in the example 40 um.

Nothing prevents from arranging the values of one, or the other, or both the parameters on the respective axis of the diagram in a different way, as well as exchanging the Cartesian axis chosen for the arrangement of the values that can be taken by the two parameters.

The diagram which is displayed to the user advantageously comprises a line grating that subdivides the plane portion identified by the two Cartesian axis in a plurality of contiguous areas, which define different stages of glaucomatous damage. The lines of the grating may be straight line segments, arcs, curve lines, based on the type of representation employed for the values of the two parameters on the two Cartesian axis.

Particularly, the line grating defines a sector 305 about the left higher vertex of the diagram (corresponding to values of the parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant" equal to 120 μιη) which corresponds to a normal condition of the patient, five bands 310, 315, 320, 325 and 330 which, distancing from said sector 350 toward the right lower vertex of the diagram (corresponding to values of the parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant" equal to 40 μιη), correspond to a "border" condition and to four subsequent stages of the glaucomatous damage entity, respectively, and a sector 335 about the right lower vertex of the diagram which corresponds to a fifth stage of the glaucomatous damage entity. As a consequence, the line grating defines, in addition to the normal condition, six progressive stages of gravity of the glaucomatous damage.

Moreover, the diagram comprises two line segments 340 and 345 that intersects one to each other at the left higher vertex of the diagram and that divaricates toward the right lower vertex, adapted to identify, in the plane portion covered by the diagram, three different sub-portions, corresponding to three different damage localizations (lower damage, higher and lower mixed damage, and higher damage).

In other words, the diagram provided with line grating and line segments represents a reference structure comprising a plurality of contiguous areas in the plane each one comprising a corresponding plurality of sets of predetermined pair of values of the parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant", wherein each area corresponds to a respective gravity and localization class of the glaucomatous damage.

By reporting in a Cartesian plane the values of the parameter "average of the RNFL thickness of the higher quadrant" on a plane, for example the abscissa axis, and the values of the parameter "average of the RNFL thickness of the lower quadrant", for example the ordinate axis, the shape and/or the position (in such Cartesian plane) of the grating line which define the different stages of different types of glaucomatous damage, the shape and/or the position (in such Cartesian plane) of the line segment which identify the localizations of the damage, and/or the trend of the values of the parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant" with respect to the line grating and to the line segments depend on the age and on the race of the patient, as well as on the type of acquisition instruments 110, 115 that have been employed.

For example, while the exemplificative diagram illustrated in Figure 3 corresponds to a patient having an age of 50 years, Figure 4 illustrates instead a diagram corresponding to a patient having an age of 74 years. Unlike the diagram of Figure 3, in the diagram illustrated in Figure 4 the values of the parameter "average of the RNFL thickness of the higher quadrant" are reported on the abscissa axis with a decreasing trend from left to right, from a maximum value of average thickness equal to 115 μιη, to a minimum value of average thickness equal to 5 μιη, while the values of the parameter "average of the R FL thickness of the lower quadrant" are reported on the ordinate axis with an increasing trend from the bottom to the top, from a minimum value of average thickness equal to 45 μιη, to a maximum value of average thickness equal to 125 um.

The selection of the diagram corresponding to block 240 of the operation flow, may be carried out by selecting among a plurality of predetermined diagrams (each one corresponding to particular combinations of age and/or race of the patient and/or to the type of acquisition instruments), or the proper diagram may be directly calculated from time to time by the system 105 by means of mathematical operations depending on the age and/or race of the patient and/or on the acquisition instruments type.

The diagrams to be selected, and/or the mathematical formulas used for calculating them, may be defined in a proper memory structure, for example in a database included/coupled in/to the system 105. For example, each diagram may be represented by means of curves which define the corresponding areas to the various classes of gravity and localization of glaucomatous damage, by means of coordinates of the ends of such areas, or also by means of a digital image. Moreover, the classes of gravity and localization may be defined by means of lists and tables, for example configured to specify for each pair of values of the parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant" the corresponding class of gravity and localization of glaucomatous damage.

The system 105 is configured to display to the user a point on the diagram representing the crossing between the values of the parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant" obtained by the selected SD-OCT, for the considered patient. The point representing the crossing between the values of the parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant" will fall in one of the seven areas 305, 310, 315, 320, 325, 330, 335 of the diagram, allowing in this way an immediate individuation of the glaucomatous disease degree, and within one of the three plane sub-portions defined by the line segments 340 and 345, allowing in this way an immediate determination of the damage localization.

The user may advantageously insert notes and comments relating to the outcomes (block 250).

The system 105 may advantageously archive (memorize) data relating to the medical reporting of the patient (block 255).

If desired, the user may request the system 105 to generate a printing of the report relating to the patient (block 260).

Aclocalicording to another embodiment of the present invention, instead of displaying a point on the diagram representing the crossing between the values of the two parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant" obtained by the selected SD-OCT, the system 105 may be configured to directly provide an indication about the class of gravity and localization of the glaucomatous damage.

Although in the present description reference has been made to a system 105 configured to display the diagram and/or the indication of the class of gravity and localization of glaucomatous damage on a displaying device 125 (for example a monitor), similar considerations apply in case the diagram and/or the indication of the class of gravity and localization of glaucomatous damage are visualized in a different manner, for example printed on sheets by means of a printer device.

The operation flow of Figures 2A and 2B is a (data processing) method which may be carried out by the data processor of the system 105 without any interaction with the patient (and particularly with measurements of the values of the two parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant" carried out before the execution of the method), or in any case without any substantial physical operation on the patient which requires the intervention of an expert medic, or which may cause potential physical damage to the patient. Moreover, the proposed solution may be employed also by a system that is not coupled with any acquisition instrument; in this case, the values of the two parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant" may be provided to the system in a different way, for example transferred by means a network connection or by means of a removable memory digital support.

The concept of the present invention may be also applied without exploiting a system comprising a programmable data processor, but also by means of the manual identification of the class of gravity and localization of glaucomatous damage on a two- dimensional Cartesian diagram such as the one previously described, but depicted on any displaying support, starting from a pair of values of the parameters "average of the RNFL thickness of the higher quadrant" and "average of the RNFL thickness of the lower quadrant", for example obtained by means measurements carried out through SD-OCT devices or in other ways.