WO2011031208A2

WO2011031208A2 - A method, an arrangement, an eye pressure gauge and use thereof

Info

Publication number: WO2011031208A2
Application number: PCT/SE2010/050920
Authority: WO
Inventors: Anders Eklund; Per Hallberg
Original assignee: Bioresonator Ab
Priority date: 2009-09-10
Filing date: 2010-08-27
Publication date: 2011-03-17
Also published as: SE0950648A1; WO2011031208A3

Abstract

This invention concerns a method for the placement of a contact tonometer (7) against an eye D for measurement of the intraocular pressure comprising automatic driving of the contact tonometer towards the eye through the start of displacement of the contact tonometer 7 that is controlled by a motor and subject to feedback, and automatic interruption of the displacement of the contact tonometer (7) towards the eye D that is controlled by a motor and subject to feedback. The invention concerns also an arrangement, an eye pressure gauge and the use of the eye pressure gauge.

Description

A method, an arrangement, an eye pressure gauge and use there of Technical area

This invention concerns a method for the placing of a contact tonometer in contact with an eye for measurement of the intraocular pressure according to the introduction to claim 1 , an arrangement according to the introduction to claim 10, an eye pressure gauge according to the introduction to claim 19 and the use of the eye pressure gauge according to claims 32 and 33. Background

Many disease diagnoses can be made from the internal pressure of the eye, known as the "intraocular pressure", abbreviated "IOP". Measurement of the intraocular pressure is sometimes combined with the results from other specimens or studies, or both. An eye pressure gauge is normally used to measure the intraocular pressure. The eye pressure gauge is manually placed in contact with a patient's eye by an operator, and pressed against the eye in order to register parameters of the eye that can be related to its internal pressure. The intraocular pressure is normally calculated based on knowledge of the force with which the eye pressure gauge has been pressed against the eye and the dimension of the contact area.

It is known that it is possible to use a constant dimension for the contact area and constant pressure for a predetermined period, and it is also known that it is possible to use dynamic phases of contact in order to determine the intraocular pressure.

There is always a risk associated with manually placing an object against the eye. The operator who places the eye pressure gauge against the eye, the one who adjusts the force of pressure of the sensor against the eye and who reads the result, should be familiar with the use of the gauge, in order for the result to be considered to be reliable. But even an experienced operator can make an erroneous decision, due to the effect of human error. It is difficult to repeat the operation in the same manner every time, and there are many influencing and disturbing parameters depending on the operator, other factors that depend on the behaviour of the eye pressure gauge, and other factors that depend on how the eye reacts in various situations.

It is, first and foremost, difficult for an operator to displace an eye pressure gauge towards a patient's eye, towards the eye of another person, at a suitable speed. There may be negative consequences for the measurement result if this is carried out too rapidly or too slowly. Too rapid a displacement may surprise the patient such that he or she acts more or less instinctively, and in an undesired manner. Too slow a displacement may make the patient insecure, the body may be given too long a period to prepare such that its physical properties are influenced, or such that the patient starts to behave in an undesired manner, such as blinking or closing the eyes. It is not unusual that the operator must hold the patient's eyelid open while at the same time the eye pressure gauge is to be applied, pressed in contact with the eye and activated. Large parts of the operator's musculoskeletal system must be taken into use, and the operation may easily become unstable and unreliable due to this.

It is also difficult for an operator to see when the eye pressure gauge has reached the correct position in contact with the eye such that it is possible to start and carry out the measurement. The cornea is transparent, and this means that nearly no light is reflected. The operator does not see a distinct surface since it is transparent to light and uncoloured, which leads to problems for the positioning of the eye pressure gauge against the eye.

A further problem is that of placing the eye pressure gauge gently and sensitively against the eye such that a sudden impact against the eye is avoided, which may in itself affect the intraocular pressure in an undesired manner. This problem is that of placing the eye pressure gauge in contact with the eye in a manner that exerts the minimum possible pressure.

It is not uncommon during the activation of the measurement process itself that the operator influences the motion of the eye pressure gauge, both towards and away from the eye. Either of these events will affect the measurement result negatively.

Thus, operation of the eye pressure gauge is not always easy, and the safety of the patient is risked at several steps. A consequence of the limitations described above is that measurement of intraocular pressure is currently carried out almost exclusively by ophthalmic specialists.

Description of the invention

One purpose of this invention is to offer a method for the placing of a contact tonometer in contact with the eye for measurement of the intraocular pressure that makes it possible to measure a correct intraocular pressure with a lower dependence on the operator and with higher patient safety. The invention comprises also an arrangement that makes this method possible, an eye pressure gauge and the use of the eye pressure gauge. This purpose is achieved with a method comprising the technical characteristics that are presented in claim 1 , an arrangement comprising the technical characteristics that are presented in claim 10, an eye pressure gauge comprising the technical characteristics presented in claim 19 and the use of the eye pressure gauge according to claims 32 and 33.

Brief description of drawings

Fig. 1 shows an arrangement according to the invention in use.

Fig. 2 shows an eye pressure gauge according to the invention.

Fig. 3 shows an exploded drawing of an eye pressure gauge according to the invention.

Designations used in the drawings:

A the arrangement according to the invention

B eye pressure gauge

B1 principal part of the eye pressure gauge

B2 housing of the eye pressure gauge base

C positioning unit

C1 support

C2 mount

D eye

E sight beam

F distance between contact tonometer and eye

G sensors

1 housing for eye pressure gauge principal part, right part

2 housing for eye pressure gauge principal part, left part

3 hygiene cover

4 force sensor arm

5 light arrangement

6 contact tonometer head

7 contact tonometer

8 contact tonometer housing

9 motor-drive rail

10 motor, miniature motor

11 force sensor plate

2 attachment arrangement for force sensor 13 screws for mounting the force sensor plate on arm

14 guide pegs

15 attachment part for hygienic cover

16 mini PCB

17 screw for mounting the force sensor on arm

18 force sensor

19 nut

20 screw for mounting the eye pressure gauge housing

21 guidance and control unit

22 guidance and control system

23 a position and motion sensor.

Detailed description of embodiments

One purpose of this invention, as stated above, is to offer a method for the placing of a contact tonometer 7 in contact with an eye D for measurement of the intraocular pressure, IOP, that makes it possible to measure a correct intraocular pressure with a lower dependence on the operator and with higher patient safety. The method also makes it possible to measure a correct intraocular pressure with simplified operation, with increased ease of use, with a more uniform operation, and with a lower dependence on the biomechanical properties of the eye.

It is appropriate that the patient whose intraocular pressure is to be measured sits down. In order to stabilise the patient's head and prevent undesired movements, the patient is to rest the head on a fixed head support, normally having support parts under the chin of the patient and against the forehead of the patient.

One fundamental feature of the invention is that it concerns motorised displacement, movement, of the contact tonometer 7 towards the eye D under feedback control.

It should be understood that the term "contact tonometer" is here used to denote either the contact tonometer itself or a contact tonometer united with other parts that facilitate its operation. What is important for the measurement of intraocular pressure is the contact tonometer, while it is its placement and displacement that are of interest, independently of the design of other parts. The method for the placement of a contact tonometer 7 in contact with an eye D for measurement of the intraocular pressure is characterised by an automatic movement of the contact tonometer towards the eye through the start of motion, displacement, of the contact tonometer that is controlled by a motor and subject to feedback, and an automatic interruption of the motion, displacement, of the contact tonometer towards the eye that is controlled by a motor and subject to feedback.

The contact tonometer 7 and its associated equipment comprising, for example, a sensor measure the force of contact, the area of contact, the position of the sensor and the speed of the sensor continuously during a measurement phase. In order to obtain reliable measured values, the measurement phase is repeated at least twice, appropriately three times, in order to make it possible to obtain an average value.

The method comprises the positioning of the contact tonometer 7 in front of the eye D such that the contact tonometer 7 is centrally located relative to the eye, the pupil of the eye, and at a distance F from the eye that is suitable for the continued movement of the contact tonometer. When the contact tonometer 7 is to be placed in contact with the eye, it is appropriate that the contact tonometer be located as close to the eye as is possible, without being so close that the patient becomes disturbed by this. It is, for example, appropriate that the contact tonometer is located at such a distance from the patient that the patient does not come into contact with the contact tonometer in advance; by feeling it, for example, by its contact with the eyelashes.

Positioning of the contact tonometer takes place either manually or automatically.

The contact tonometer 7 is mounted on a positioning unit C, a support C1 , in front of the eye, which makes it possible to position the contact tonometer. The contact tonometer is directly or indirectly mounted on, coupled with, the positioning unit C in various manners and, alternatively, through various arrangements.

The generation and direction of a sight beam E, a guiding light, from the contact tonometer 7 towards the eye D, is used to determine and delineate a central region of an area of contact on the eye, against which the contact tonometer is to be driven automatically.

Automatic positioning can be controlled by measurement of the light reflected from the eye. When the sight beam is directed towards the pupil and centred in the pupil, a very small amount of light will be reflected, and this can then be interpreted as indicating that the positioning has been correctly carried out. A control parameter is obtained by measurement of light intensity using a sensor, which parameter is used for the control of the positioning unit. If the eye is illuminated using a sight beam with a scanning motion, the reflection can be interpreted as a value related to the positioning and it can give information about when the correct position has been achieved. The automatic movement of the contact tonometer towards the eye comprises a gentle-start function and a gentle-stop function. The gentle-start function and the gentle-stop function help to minimise oscillations in the power of the contact tonometer and neighbouring parts. With a known, predefined, predetermined stop condition and with a known, predefined, predetermined speed, the contact tonometer can be displaced until the stop condition has been satisfied. It is possible to select a suitable method of signal analysis that eliminates the influence of the deceleration on the measurement result. The automatic driving of the contact tonometer towards the eye takes place with the aid of servo control. The term "servo control" is here used to denote the fact that the motion is standardised and that the motor is controlled by feedback signals from position, force and surface detectors, in order to obtain this standardised pattern of motion with respect to the speed of the starting procedure, the transport procedure and the stopping procedure. A servo-controlled contact tonometer is controlled through feedback from measurable parameters, such as the continuous measurement of force and area of contact.

Manual placement of contact sensors and eye pressure gauges creates, as has been stated above, problems of many types, which are described above. The measurement result does not always correspond to reality: the measurement results contain errors. One general problem is that a non-standard procedure for motion towards the eye in preparation for and during applanation, creates measurement problems. A staccato manual motion gives oscillations that disturb the measurement of force and give rise to errors in the measurement, differing applanation speeds and deceleration movements influence the measurement result through viscoelastic and biomechanical influences in a negative direction, and the presence of different initial depths of indentation from manual application. An unnecessarily long time for application, the time for contact, against the eye in the event of uncertainty on the part of the operator concerning if and when the measurement is complete increases the risk of patient discomfort and, in the worst case, complications.

The standardised method that this invention concerns entails standardised movements through an automatic method that is ensured through the determination of safety parameters that control and regulate the application, the arrangement, and the execution, which results in reliable measured values while enabling the safety of the patient to be ensured at the same time. The invention also results in the measurement procedure becoming significantly simplified. This reduces the time required for training an operator and requirements for the operator's experience. This will have as a consequence that more professional groups within the healthcare system will be able to carry out the measurement of intraocular pressure in a safe and reliable manner, not just persons with special ophthalmic expertise, ophthalmic specialists.

A second purpose of the invention is, as has been stated above, to offer an arrangement that makes the method described above possible.

The invention comprises an arrangement A that comprises a contact tonometer 7, a displacement unit 9 that makes possible driving of the contact tonometer 7 towards the eye D, a motor unit 10 that makes possible the automatic driving of the contact tonometer towards the eye and a guidance and control unit 21 for the start of a movement, the displacement, of the contact tonometer that is controlled by a motor and subject to feedback, and for the automatic interruption of the movement, the displacement, that is controlled by a motor and subject to feedback, of the contact tonometer towards the eye. The arrangement A comprises a positioning unit C for positioning of the contact tonometer 7 in front of the eye D such that the contact tonometer is located at a distance F from the eye that is suitable for the continued movement of the contact tonometer.

The positioning unit C comprises parts that make possible manual control and regulation or automatic control and regulation. The positioning unit comprises a support C1 to which the contact tonometer is connected.

The arrangement A comprises a light arrangement 5 for the generation and direction of a sight beam, a guiding light, from the contact tonometer 7 towards the eye D, to determine and delineate a central region of an area of contact on the eye, against which the contact tonometer is to be driven automatically.

In order to automate the positioning operation, it is appropriate that the arrangement comprise a sensor 23 for measurement of light intensity connected to the motor-driven control of the contact tonometer. It is appropriate that this sensor 23, which is a position and motion sensor, be comprised within the light arrangement 5. A photodiode measures the light from the sight beam that is reflected by the eye, by the cornea of the eye. The intensity of the reflected light is related to the centring of the sensor against the cornea. The pupil reflects light poorly, so when the amount of reflected light is low, the contact tonometer is located relatively centrally in the pupil. When much light is reflected, the tonometer is directed towards a region within the iris, or in the boundary between the iris and the pupil, and is thus insufficiently centred.

It is appropriate that the positioning unit C to which the contact tonometer 7 is connected comprise a mount C2 in the form of a plate or similar that makes possible the mounting of the contact tonometer and that can be moved in the x-, y- and z-directions [Swedish "och/eller"]: horizontally, vertically and backwards/forwards, relative to the support C1. The movement and the control of the mount takes place through a guidance and control system 22 that may be an integral part of the previously mentioned guidance and control unit 21, or it may be an independent system. It is possible to coarsely locate the contact tonometer 7 in front of the eye D through manual movement of the mount C2 and thus of the tonometer, and then to carry out an automatic fine adjustment, accurate location, a positioning of the contact tonometer. It is possible through an automatic scanning motion and automatic measurement of the reflected light to place the tonometer automatically in the centre in front of the pupil.

The arrangement A comprises the guidance and control unit 21 that deals with the automatic displacement of the contact tonometer towards the eye and which in turn comprises a unit that makes possible the gentle-start function and the gentle-stop function. The guidance and control unit 21 comprises servo control.

A further purpose of the invention is to offer an eye pressure gauge B and the use of the eye pressure gauge in order to be able to exploit the method and the arrangement.

An eye pressure gauge B according to the invention comprises a contact tonometer 7, a displacement unit 9 that makes it possible to drive the contact tonometer towards the eye D, a motor unit 10 that makes it possible to drive the contact tonometer towards the eye automatically and a guidance and control unit 21 for the start of a movement, displacement, of the contact tonometer that is controlled by a motor and subject to feedback, and for the automatic interruption of the movement, displacement, that is controlled by a motor and subject to feedback, of the contact tonometer towards the eye. The motor unit 10 is located in association with the contact tonometer 7. The eye pressure gauge B comprises a miniature motor 10 with a stroke length of between 1 and 40 mm. The motor 10 guides the contact tonometer into and out from the housing 1 + 2 of the eye pressure gauge. The stroke length has been chosen such that it is possible to displace the contact tonometer, its outermost part directed towards the eye, at least through the appropriate distance F at which the contact tonometer is located in front of the eye such that the contact tonometer reaches the eye during its displacement towards the eye.

In order to create a safe and robust measurement of force, one force sensor 18, for example, can be located in a base part B2 comprised within the eye pressure gauge B. Weight, mass, from various component parts that are located inside a principal part B1 comprised within the eye pressure gauge creates forces that disturb the measurement. This placement of the component parts of the eye pressure gauge results in vibration and the forces of acceleration and deceleration being recorded during the measurement of force due to the mass in the principal part B1 and acceleratory movements in the principal part B1 that depend on it. This influence on the measurement of force can be limited by a miniature motor 10. The miniature motor 10, a small and light motor, makes it possible to have a minimal motor in the principal part B1 of the eye pressure gauge. The miniature motor uses a gentle-start function in order to subsequently pass over into a speed that is adapted for the measurement situation during the movement of the contact tonometer, [sic, "which" missing] results in a measurement situation with few disturbing events and disturbing forces. A miniature motor with a standardised motion is optimised to achieve optimal measurement precision during the measurement of intraocular pressure and other biomechanical parameters.

The eye pressure gauge B comprises a light arrangement 5 for the generation and direction of a sight beam, a guiding light, E from the contact tonometer 7 towards the eye D, to determine and delineate a central region of an area of contact on the eye, against which the contact tonometer is to be driven automatically. The light arrangement 5 comprises also a sensor 23 for recording reflected light.

The guidance and control unit 21 comprises a unit that makes possible gentle starting and gentle stopping. The guidance and control unit 21 comprises a servo control arrangement.

The eye pressure gauge B comprises a sensor for the measurement of force, a sensor for the measurement of movement and a sensor for surface measurement. All of the sensors included in the description that have not been described in detail and displayed separately are shown purely schematically in Figure 2 with the reference letter G.

The contact tonometer 7 of the eye pressure gauge comprises a piezoelectric surface gauge or a capacitive surface gauge. By regarding the measurement system, the sensor connected to the eye, as a condenser, it is possible to obtain the area of contact from the equation for a parallel-plate condenser: d '

where C is the capacitance, d the separation of the plates, ε is the permittivity and A the surface area. The permittivity and the separation of the plates are to be regarded as sensor constants, which gives a linear relationship between the capacitance and the surface area. The capacitance is measured by measuring the impedance that arises from contact between the cornea and the sensor tip: ωΖ_$

In order to obtain a linear relationship between the capacitance and the signal, one chooses to look at the "admittance", which is defined as the inverse of the impedance. It has been shown in a previous report that the change of force relative to a change in admittance is proportional to the intraocular pressure IOP, as follows: dY ⁰

where dF is the change of force, dY the change in admittance, and c₀ is a constant.

Either the component sensors or the measurement arrangements, or both, are located at a distance from the contact tonometer, appropriately inside a base part B2 comprised within the eye pressure gauge.

An eye pressure gauge according to the invention can be used to carry out the method described. An eye pressure gauge according to the invention can be used also in the arrangement described.

[I added "determination of to some of the below to make them compatible with "method". Otherwise they would be "properties" or "parameters".] There are many different methods of analysis for biomechanical parameters, one of which is determination of the IOP. Other methods of analysis are:

-continuous measurement of force and frequency shift in order to determine ocular pulsation

-determination of corneal hysteresis

-determination of corneal rigidity -determination of ocular compliance

-oscillation of the cornea using a controlled signal to a motor subject to servo control. The phase difference between the input signal and the output signal provides an accurate determination of the corneal hysteresis.

Also the eye itself influences the measurement result. It has become apparent that the biomechanical properties of the eye before and during the determination of the intraocular pressure are complicated. It is known that the thickness of the cornea influences the measurement, as do also the curvature of the cornea, its viscoelasticity and its rigidity. Viscoelastic effects are principally related to dynamic methods of measurement.

During applanation/indentation, contact with/exerting inwards pressure, the total compliance of the eye will generate a source of error in the form of an increase in pressure that depends on the magnitude of the applanation/indentation to which the eye is exposed. The more that is known about the forces and motions, the greater will be the possibility of compensating individual variations in physical parameters and of compensating for their effects on the force/area relationship during applanation, and obtaining in this way a correct IOP Positive consequences of a standardised method according to this invention, with a controlled procedure of applanation, are not only simplified operation and increased patient safety, but also that it makes it possible to estimate these biomechanical parameters that can be used in themselves for diagnostic purposes, while at the same time obtaining a more exact determination of the intraocular pressure. These consequences together lead to the diagnosis becoming more reliable.

This description of working embodiments of the invention is to be used for increased understanding of the invention as it is described in the attached patent claims: it is not to be interpreted as limiting the invention.

Claims

1. A method when placing a contact tonometer (7) in contact with an eye (D) for the measurement of the intraocular pressure, c h a r a c t e r i s e d b y

• automatic driving of the contact tonometer (7) towards the eye (D) through the start of a displacement of the contact tonometer (7) controlled by a motor and subject to feedback, and

• automatic interruption of the displacement of the contact tonometer (7) towards the eye (D) controlled by a motor and subject to feedback.

2. The method according to claim 1 comprising the positioning of the contact tonometer (7) in front of the eye (D) such that the contact tonometer (7) is centrally located relative to the eye (D) and at a distance (F) from the eye (D) that is suitable for the continued movement of the contact tonometer.

3. The method according to claim 1 or 2 in which the positioning of the contact tonometer (7) takes place manually.

4. The method according to claim 1 or 2 in which the positioning of the contact tonometer (7) takes place automatically.

5. The method according to any one of claims 1-4, comprising the mounting of the contact tonometer (7) on a positioning unit (C, C1 , C2) in front of the eye (D) that makes possible the positioning of the contact tonometer.

6. The method according to any one of claims 1-5, comprising the generation and direction of a sight beam (E) from the contact tonometer (7) towards the eye (D), to determine and delineate a central region of an area of contact on the eye, against which the contact tonometer is to be driven automatically.

7. The method according to any one of claims 1-6, where the automatic driving of the contact tonometer (7) towards the eye (D) comprises a gentle-start function.

8. The method according to any one of claims 1-7, where the automatic driving of the contact tonometer (7) towards the eye (D) comprises a gentle-stop function.

9. The method according to any one of claims 1-8 in which the automatic driving of the contact tonometer (7) towards the eye (D) takes place with the aid of servo control.

10. An arrangement (A) that makes the method according to claim 1 possible, c h a r a c t e r i s e d i n

^■ that it comprises a contact tonometer (7), ^■ that it comprises a displacement unit (9) that makes possible movement of the contact tonometer towards the eye,

^■ that it comprises a motor unit (10) that makes possible the automatic movement of the contact tonometer towards the eye, and

■ that it comprises a guidance and control unit (21) for the start of displacement of the contact tonometer that is controlled by a motor and subject to feedback, and for automatic interruption of the displacement of the contact tonometer towards the eye that is controlled by a motor and subject to feedback.

11. The arrangement according to claim 10 comprising a positioning unit (C, C1, C2) for the positioning of the contact tonometer (7) in front of the eye (D) such that the contact tonometer (7) is centrally located relative to the eye (D) and such that the contact tonometer (7) is located at a distance (F) from the eye (D) that is suitable for the continued movement of the contact tonometer.

12. The arrangement according to claim 11, where the positioning unit (C, C1 , C2) comprises parts (C1, C2) that make possible manual control and regulation.

13. The arrangement according to claim 11, where the positioning unit (C, C1, C2) comprises parts (22) that make possible automatic control and regulation.

14. The arrangement according to any one of claims 10-13, where the positioning unit (C, C1 , C2) comprises a support (C1 ) to which the contact tonometer is connected.

15. The arrangement according to any one of claims 10-14, comprising a light arrangement (5) for the generation and direction of a sight beam (E) from the contact tonometer (7) towards the eye (D), to determine and delineate a central region of an area of contact on the eye, against which the contact tonometer is to be driven automatically.

16. The arrangement according to any one of [any one of, sic] claims 10-15, where the guidance and control unit (21) comprises a unit that makes gentle start possible.

17. The arrangement according to any one of claims 10-16, where the guidance and control unit (21 ) comprises a unit that makes gentle stop possible.

18. The arrangement according to any one of claims 10-17, where the guidance and control unit comprises servo control.

19. An eye pressure gauge (B) comprising a contact tonometer (7) c h a r a c t e r i s e d i n

• that it comprises a displacement unit (9) that makes possible movement of the contact tonometer towards the eye, • that it comprises a motor unit (10) that makes possible the automatic movement of the contact tonometer towards the eye, and

• that it comprises a guidance and control unit (21) for the start of displacement of the contact tonometer that is controlled by a motor and subject to feedback and, for automatic interruption of the displacement of the contact tonometer towards the eye that is controlled by a motor and subject to feedback.

20. The eye pressure gauge (B) according to claim 19, where the motor unit (10) is located in association with the contact tonometer.

21. The eye pressure gauge (B) according to claim 19 or 20, where the motor unit (10) comprises a miniature motor with a stroke length between 1 and 40 mm.

22. The eye pressure gauge (B) according to any one of claims 19-21, comprising a light arrangement (5) for the generation and direction of a sight beam (E) from the contact tonometer (7) towards the eye (D), to determine and delineate a central region of an area of contact on the eye, against which the contact tonometer is to be driven automatically.

23. The eye pressure gauge (B) according to any one of claims 19-22, where the guidance and control unit (21 ) comprises a unit that makes gentle start possible.

24. The eye pressure gauge (B) according to any one of claims 19-123 [sic!], where the guidance and control unit (21) comprises a unit that makes gentle stop possible.

25. The eye pressure gauge (B) according to any one of claims 19-24, where the guidance and control unit comprises servo control.

26. The eye pressure gauge (B) according to any one of claims 19-25, comprising a sensor for surface measurement.

27. The eye pressure gauge (B) according to any one of claims 19-26, comprising a sensor for force measurement.

28. The eye pressure gauge (B) according to any one of claims 19-27, where the contact tonometer comprises a piezoelectric surface gauge.

29. The eye pressure gauge (B) according to any one of claims 19-27, where the contact tonometer comprises a capacitive surface gauge.

30. The eye pressure gauge (B) according to any one of claims 26-29, where the component sensors (G) or the measurement arrangements, or both, are located at a distance from the contact tonometer.

31. The eye pressure gauge (B) according to claim 30, where the component sensors (G) or the measurement arrangements, or both, are located within a base part (B2) comprised within the eye pressure gauge.

32. The use of an eye pressure gauge (B) according to claim 19 during the execution of the method according to claim 1.

33. The use of the eye pressure gauge (B) according to claim 19 in an arrangement according to claim 10.