Combined open-loop and / or closed-loop control of an injection pressure of a fluid and of an intraocular pressure when injecting the fluid between two tissue layers of the human eye

Abstract

The invention relates to a control device (10) for open-loop and / or closed-loop control of an injection pressure of a fluid and of an intraocular pressure when injecting the fluid at an injection site between two tissue layers of the human eye (1). The control device (10) contains an open-loop or closed-loop control unit which is designed for open-loop or closed-loop control of the injection pressure and the intraocular pressure in such a way that the gradient between the injection pressure and the intraocular pressure assumes a predetermined value.

Description

[0001] Combined control and / or regulation of an injection pressure of a fluid and an intraocular pressure when injecting the fluid between two tissue layers of the human eye.

[0002] The present invention relates to a control device for controlling and / or regulating an injection pressure of a fluid, i.e. a liquid or a gas, and an intraocular pressure when injecting the fluid at an injection site between two tissue layers of the human eye, for example between the neuronal layer of the retina and the retinal pigment epithelium.The invention further relates to an arrangement for injecting a fluid at an injection site between two tissue layers of the human eye, for example between the neuronal layer of the retina and the retinal pigment epithelium, a computer program, a non-volatile computer-readable storage medium, an arrangement for performing ophthalmic operations and a method for controlling and / or regulating an injection pressure of a fluid and an intraocular pressure when injecting the fluid at an injection site between two tissue layers of the human eye, for example between the neuronal layer of the retina and the retinal pigment epithelium.

[0003] In a subretinal injection, fluid is introduced between two layers of the retina via a cannula, for example, between the neuroepithelial layer of the retina (stratum neuroepitheliale) and the retinal pigment epithelium. This procedure takes advantage of the fact that the interaction between these layers, such as the neuroepithelial layer and the retinal pigment epithelium, is based on relatively weak molecular bonds. Even slight pressure differences between the subretinal space and the intraocular pressure can lead to detachment of the retina from the choroid. This results in the formation of a fluid-filled blister, known as a bleb. A 41-gauge cannula, such as those manufactured by DORC Dutch Ophthalmie Research Center (International) BV or MedOne Surgical, Inc., can be used for this procedure.Typical applications of subretinal injection include the introduction of saline solutions, the dissolution of subretinal hematomas by injection of plasminogen activator and air, as well as gene therapy procedures in which viral gene vectors are introduced, and stem cell therapy.

[0004] The geometry of the bleb, particularly its location, size, and geometric shape, and the rate of its formation are essential factors determining treatment success. Slow and controlled bleb formation protects the delicate retinal tissue, ensures good metabolism of the injected fluid, especially any injected medication, and thus contributes to the high efficacy of the injected drug.

[0005] It has also been shown that low intraocular pressure promotes a preferential, i.e., slow and controlled, bleb formation. However, a gradient between the intraocular pressure (lower pressure) and the injection pressure (higher pressure) of the fluid is necessary for bleb formation. Intraocular pressure can be controlled using a vitrectomy device. However, this only allows for limited control of desired bleb formation. With manual injection of the fluid, the injection pressure typically varies considerably, which can lead to very high pressure at times and rapid, difficult-to-control bleb formation. To avoid this, a defined injection pressure can be used, for example. However, it may be necessary to change the intraocular pressure during the injection, which in turn influences bleb formation.Document US 8,608,665 B2 describes a method for detecting injection pressure at the needle of a syringe. Document WO 2011 / 139713 A2 discloses a method and a device for delivering a drug into ocular tissue using a microinjection needle. The article by Xue, K. et al., "Technique of retinal gene therapy: delivery of viral vector into the subretinal space," Eye (2017) 31, 1308-1316, describes the delivery of a viral vector into the subretinal space as part of a retinal gene therapy procedure. The injection is controlled by a foot pedal.

[0006] Document DE 10 2021 210 484 A1 describes a console for an ophthalmic surgical system. Document DE 10 2021 111 178 A1 discloses a method for operating a fluid pump of an ophthalmic surgical system.

[0007] Against the background described above, the object of the present invention is to provide an advantageous control device for controlling and / or regulating the injection pressure of a fluid and the intraocular pressure when injecting the fluid at an injection site between two tissue layers of the human eye. Further objects are to provide an equally advantageous arrangement for injecting a fluid, a computer program, a non-volatile, computer-readable storage medium, an arrangement for performing ophthalmic operations, and a method for controlling and / or regulating the injection pressure of a fluid and the intraocular pressure when injecting a fluid at an injection site between two tissue layers of the human eye.

[0008] The aforementioned problems are solved by a control device according to claim 1, an arrangement for injecting a fluid according to claim 6, an arrangement for performing ophthalmological operations according to claim 7, a computer program according to claim 8, a non-volatile, computer-readable storage medium according to claim 9, and a method for controlling and / or regulating an injection pressure of a fluid and an intraocular pressure when injecting a fluid at an injection site between two tissue layers of the human eye according to claim 10. The dependent claims contain further advantageous embodiments of the invention.

[0009] The control device according to the invention for controlling and / or regulating the injection pressure of a fluid and the intraocular pressure during injection of the fluid, e.g., using a microinjection syringe, at an injection site between two tissue layers of the human eye, includes a control or regulating unit. The control or regulating unit is designed to control or regulate the injection pressure, e.g., at the microinjection syringe, and the intraocular pressure in such a way that the gradient between the injection pressure and the intraocular pressure assumes a predetermined, i.e., fixed, value. The gradient between the injection pressure and the intraocular pressure is hereinafter also referred to as the pressure gradient.

[0010] The present invention has the advantage that two separate pressure values, namely the intraocular pressure and the injection pressure, which are usually given in different units, do not need to be set independently of each other and, if necessary, controlled separately. Intraocular pressure is usually given in mmHg and injection pressure in PSI. These two units differ by a factor of 50, which makes a quick comparison of the two values ​​difficult. The present invention improves the reliability and controllability of bleb formation.

[0011] Within the scope of the present invention, the control and / or regulation of intraocular pressure and the control and / or regulation of injection pressure are linked by controlling and / or regulating the gradient, i.e., the difference between the two. In this context, a predetermined intraocular pressure adapted to the patient's needs can be determined and set, and a desired pressure gradient can be defined, which is then automatically maintained. If necessary, the intraocular pressure can be changed or adjusted during the process, without having to consider the formation of the bleb, since the formation of the bleb depends on the automatically controlled gradient and is therefore not affected by a change in intraocular pressure.By continuously and interlinkingly controlling the gradient between intraocular pressure and injection pressure, reliable bleb formation can be ensured.

[0012] The gradient can, for example, be kept constant during injection. The specified gradient value can lie within a predefined, i.e., fixed, range. In this case, the specified value can be adjusted during injection or does not need to be precisely achieved at every point in time, while the range specification still ensures that a controlled gradient is maintained throughout the injection.

[0013] The control device can be designed for manual or automated control and / or regulation of the pressure gradient. The control device can include an electronic control and / or regulation unit for mechanical control and / or regulation of the pressure gradient. In other words, the control and / or regulation can be electronic and / or mechanical. The resolution or accuracy of the injection pressure adjustability is, for example, less than 1 PSI, or less than 1 mmHg.

[0014] The control device may include a device for determining, in particular for recording, calculating, or measuring, the current injection pressure and / or a device for determining, in particular for recording or measuring, the current intraocular pressure. The device for determining the current injection pressure, which may include a pressure sensor, and / or the device for determining the current intraocular pressure, which may also include a pressure sensor, are preferably connected to the control unit for data transmission. This variant has the advantage of enabling precise control and / or regulation of the gradient with a short response time. The device for determining the current intraocular pressure may be part of a vitrectomy device and arranged as a pressure sensor on an infusion line.

[0015] Preferably, the control device is designed to control and / or regulate the injection pressure by controlling and / or regulating an actuating device of an injection syringe. In particular, the control device can be designed to control and / or regulate the pressure and / or force on a piston of the injection syringe and / or to control and / or regulate the speed of the piston's movement in the injection syringe, e.g., the movement of the piston relative to the injection syringe or to a reference point of the injection syringe.

[0016] Furthermore, the control device can be designed for continuous, i.e., permanent, control and / or regulation of the gradient. It can also be designed for control and / or regulation of the gradient at defined time intervals. In another variant, the control device can be designed to control and / or regulate the gradient depending on the injected volume of fluid. The injected volume is related to the injection velocity of the fluid and / or the force exerted on the piston.

[0017] Advantageously, the control device includes a user interface (HMI - Human Machine Interface) designed for entering predefined values ​​of the gradient and / or intraocular pressure and / or permissible ranges of intraocular pressure and / or injection pressure. This allows for individual input by the user to control and regulate the injection.

[0018] The arrangement according to the invention for injecting a fluid at an injection site between two tissue layers of the human eye comprises a microinjection syringe, an actuating device for actuating the microinjection syringe, a device for adjusting the intraocular pressure, and a previously described control device according to the invention for controlling and / or regulating the injection pressure of the fluid and the intraocular pressure during injection of the fluid, which is functionally connected to the actuating device for actuating the microinjection syringe and the device for adjusting the intraocular pressure. The arrangement according to the invention for injecting a fluid has the same features and advantages as the control device according to the invention described above.

[0019] The arrangement according to the invention for performing ophthalmological operations comprises a previously described arrangement according to the invention for injecting a fluid. It has the features and advantages already described in this context.

[0020] The computer program according to the invention for controlling and / or regulating an injection pressure of a fluid and an intraocular pressure when injecting the fluid at an injection site between two tissue layers of the human eye comprises instructions which, when executed on a computer, cause it to control and / or regulate the injection pressure and the intraocular pressure in such a way that the gradient between the injection pressure and the intraocular pressure assumes a predetermined value.

[0021] The non-volatile, computer-readable storage medium according to the invention contains stored instructions for controlling and / or regulating the injection pressure of a fluid and the intraocular pressure when injecting the fluid at an injection site between two tissue layers of the human eye. When executed on a computer, these instructions cause the computer to control and / or regulate the injection pressure and the intraocular pressure such that the gradient between the injection pressure and the intraocular pressure assumes a predetermined value. The computer program and the non-volatile, computer-readable storage medium according to the invention have the advantages already described above. They enable automated control and / or regulation of the injection process.

[0022] The inventive method for controlling and / or regulating the injection pressure of a fluid and the intraocular pressure during the injection of a fluid at an injection site between two tissue layers of the human eye comprises the following steps. The current intraocular pressure is determined, e.g., set, fixed, predetermined, detected, or measured. A setpoint value for the gradient between the intraocular pressure and the injection pressure is predetermined, e.g., set or defined. The current injection pressure is determined, e.g., calculated, detected, or measured. The gradient, i.e., the current pressure gradient, is controlled and / or regulated during the injection by controlling and / or regulating the injection pressure and / or the intraocular pressure so that the predetermined setpoint value of the gradient is reached, e.g., adjusted, achieved, or maintained. The inventive method can, for example,The injection of a fluid can be carried out using the control device or the arrangement according to the invention. It has the features and advantages already described in this context.

[0023] In an advantageous embodiment, the injection pressure is controlled and / or regulated by controlling and / or regulating an actuating device of an injection syringe. In particular, the pressure and / or force on the piston of the injection syringe and / or the speed of the piston's movement in the injection syringe can be controlled and / or regulated.

[0024] In another variant, the current injection pressure is determined by means of a sensor and / or based on a detected force acting on the piston of the injection syringe and / or a detected pressure acting on the piston of the injection syringe and / or a determined, e.g. calculated or measured, speed of the movement of the piston in relation to the injection syringe.

[0025] The current intraocular pressure can be detected, e.g., measured, using a pressure sensor on an infusion line of a vitrectomy device.

[0026] Advantageously, a target intraocular pressure (IOP) value can be predefined, i.e., set. This target IOP value can be adjusted before and / or during the injection. The target IOP value can fall within a defined range. For example, an IOP value to be set before and / or during the injection can be individualized for a specific person or for a specific group of people.

[0027] The target value or target value range for intraocular pressure can be determined based on at least one defined parameter, e.g., physical or personal. Individual medical indications can be taken into account in this process.

[0028] Intraocular pressure can be altered or adjusted, for example during injection, if at least one predetermined condition, such as a specific or determinable condition, is met. A change or adjustment of intraocular pressure may be medically indicated and / or necessary for controlling and / or regulating the pressure gradient.

[0029] The gradient can be controlled and / or regulated continuously or at defined time intervals. Optionally, the gradient can be controlled and / or regulated depending on the injected volume of fluid. In another variant, the gradient can be kept constant or within a defined range or interval, e.g., between a predetermined upper limit and a predetermined lower limit. Preferably, the pressure and / or force on the piston of the injection syringe and / or the speed of the piston's movement within the injection syringe, e.g., relative to a suitable reference point on the injection syringe, are controlled and / or regulated to control and / or regulate the gradient. The control and / or regulation can be implemented in an open and / or closed control loop.

[0030] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying figures. Although the invention is illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by a person skilled in the art without departing from the scope of protection of the invention.

[0031] The figures are not necessarily detailed or to scale and may be enlarged or reduced to provide a better overview. Therefore, the functional details disclosed here are not to be understood as limiting, but merely as an illustrative basis to guide those skilled in this field of technology in using the present invention in a variety of ways.

[0032] The expression "and / or" used here, when used in a series of two or more elements, means that each of the listed elements can be used alone, or any combination of two or more of the listed elements can be used. For example, if a composition is described as containing the components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0033] Fig. 1 schematically shows a bleb formed during a subretinal injection and an arrangement for its generation. Fig. 2 schematically shows an arrangement according to the invention for injecting a fluid at an injection site between two tissue layers of the human eye.

[0034] Fig. 3 schematically shows a variant of a method according to the invention for controlling and / or regulating an injection pressure of a fluid and an intraocular pressure when injecting a fluid at an injection site between two tissue layers of the human eye in the form of a flow diagram.

[0035] Figure 1 schematically shows a bleb 16 or blister forming after a subretinal injection. The schematically depicted eye 1 is connected to an infusion line 2, which may include a device for determining, e.g., setting, fixing, or measuring, the intraocular pressure (IOP). The infusion line 2 and, if applicable, the IOP determination device may be part of an intraocular BSS infusion line, which may be connected to a vitrectomy device. The vitrectomy device may have a user interface that allows healthcare professionals to control and / or regulate the IOP.

[0036] A fluid, for example a liquid or a gas, is injected subretinal into the tissue of the eye 1 using a syringe 3, preferably a microinjection syringe. A bubble or so-called bleb 16 with an internal pressure pe forms between two tissue layers of the eye 1.

[0037] The syringe 3 has a cannula 4, which is fluidically connected to a cylindrical body 8 with a cylindrical cavity 5 for receiving the fluid. The syringe 3 also has a piston 6, which can be moved longitudinally within the cylindrical cavity 5, thereby influencing the volume of the cavity 5. The direction of movement of the piston 6 during injection is indicated by an arrow 7. A force F or a pressure p is applied to the piston 6 to cause it to move. This results in the piston 6 moving at a velocity v relative to the syringe 3, for example, relative to the cylindrical body 8 and / or the cannula 4. The movement of the piston 6 can be controlled and / or regulated by means of an actuating device (not explicitly shown).

[0038] Actuation, in particular movement, of the piston 6 causes a pressure pi of the fluid located in the cylindrical cavity 5 to be set. The cylindrical cavity 5 has a cross-sectional area Ai. The cannula 4, which is connected longitudinally to the cylinder body 8, has a length L2, a radius r, and a cross-sectional area A2. When the piston 6 is actuated, the fluid entering the cannula 4 has a pressure P2. The fluid flows in the cannula 4 at a flow velocity v. c The fluid flowing out of cannula 4 has a pressure p0. The infusion creates a pressure e in bleb 16.

[0039] A constant velocity v of piston 6 results in a constant volume flow rate v * A of the fluid. The same volume flows through cannula 4. Therefore: v c = — ■ v. The force F on piston 6 is: F = A ■ p1. According to According to Bernoulli's equation: p + 0.5 ■ roh ■ v 2 = p2+ 0.5 ■ roh ■ v 2 Here, ρ or p denotes the density of the fluid. If the velocity c As the pressure rises, the pressure P2 falls. In cannula 4, the pressure drops from the inlet pressure P2 to the outlet pressure po according to the Hagen-Poiseuille law:

[0040] Here, pi denotes the number TT and nu or v the dynamic viscosity of the fluid.

[0041] According to the present invention, the pressure gradient Ap: p0= p I0P The pressure gradient Ap is set and subsequently controlled and / or regulated. Depending on the specified pressure gradient Ap, a specific volume flow rate or injection velocity v is determined. c- A2 set. Hydrostatic pressure provides a relationship between the fill level of a liquid and the pressure at the bottom of a container holding the liquid. It is calculated according to Pascal's law: p( / i) = pgh + p F Here, p denotes the density of the fluid, g the acceleration due to gravity, h the height of the fluid level above the point under consideration, PF the pressure at the fluid surface, and p(h) the hydrostatic pressure as a function of the height h of the fluid level. Torricelli's theorem provides a relationship between the height h of the fluid level above an outlet and the resulting outflow velocity v of the fluid through the outlet:

[0042] A combination of the two formulas mentioned provides a relationship between the pressure of the fluid and the resulting velocity:

[0043] The pressure difference Ap corresponds to a theoretical height difference. This theoretical height difference leads to a dependence of the injection velocity vc through cannula 4 on the pressure gradient Ap.

[0044] This is an ideal value which must be multiplied by a factor when taking into account the geometry of the outlet opening.

[0045] This approach allows for the control and / or regulation of the pressure gradient Ap using either the force F acting on the piston 6 of the injection syringe 3 to inject the fluid as an input variable, or the velocity v of the longitudinal movement of the piston 6 in the cylindrical hollow body 8 as an input variable. The following table shows an example calculation. To simplify the calculation, an intermediate piece typically arranged between the syringe body (i.e., the cylindrical hollow body 8) and the cannula 4, e.g., a 23G / 25G element, has been neglected.

[0046] According to the calculation, a pressure of 43.6 mbar results in a volume flow rate of 0.1 pl / s through the cannula. Past experimental results for subretinal injections at an injection pressure of 60 mbar yielded a volume flow rate of 0.1 pl / s.

[0047] Figure 2 schematically shows an arrangement 15 according to the invention for injecting a fluid at an injection site between two tissue layers of the human eye. The arrangement 15 comprises a control device 10 according to the invention for controlling and / or regulating an injection pressure of a fluid and an intraocular pressure during the injection of the fluid at an injection site between two tissue layers of the human eye. The control device 10 can be configured as a computer.

[0048] In addition to the embodiment shown in Figure 1, Figure 2 shows a pressure sensor 12 for detecting the current intraocular pressure piop actual arranged on the infusion line 2. Furthermore, a pressure sensor 14 for detecting the current pressure p is located on or in the cannula 4. CThe infusion line 2 is provided in the cannula 4. The pressure sensors 12 and 14, the infusion line 2, and an actuating device (not explicitly shown) for moving the piston 6 are connected to the control device 10 for data transmission, e.g., wirelessly and / or via a wired connection. This is indicated by lines 11 and 13, where the data connections 11 connect the infusion line 2 and the pressure sensor 12 to the control device 10, and the data connections 13 connect the pressure sensor 14 and the actuating device of the piston 6 to the control device 10. This configuration enables control of the pressure gradient Ap in a closed control loop.

[0049] The control device 10 can be part of a console, wherein the console both supplies controlled fluids for, for example, the infusion line 2 and also performs control of and / or communication (wireless and / or wired) with the sensors 12, 14.

[0050] The control device 10 includes a control or regulating unit designed to control or regulate the injection pressure po and the intraocular pressure piop such that the gradient Ap between the injection pressure po and the intraocular pressure piop assumes a predetermined, fixed value. The control device 10 may include at least one user interface for entering specifications, e.g., values ​​for the intraocular pressure piop and / or the gradient Ap, or be connected to such an interface for data transmission.

[0051] In the following, a variant of a method according to the invention for controlling and / or regulating an injection pressure of a fluid and an intraocular pressure when injecting a fluid at an injection site between two tissue layers of the human eye, for example by means of an arrangement according to the invention shown in Figure 2, is explained with reference to the flow diagram shown in Figure 3.

[0052] In step 21, a desired intraocular pressure (IOP) adapted to the specific situation, or an IOP measured or estimated before the operation, is entered and thus set on a vitrectomy device or the control unit 10. This can be done in mmHg. In step 22, the current IOP actual is determined, for example, by means of the pressure sensor 12, and the corresponding data is transmitted to the control unit 10 11. The control unit 10 transmits this data as input data to the vitrectomy device for regulating the inlet pressure at an infusion line 2 to set the IOP set in step 21. The setting of the IOP set in step 21 takes place in step 23.

[0053] In step 24, a pressure gradient Ap is specified, for example, defined. This can be done via input through a user interface. In step 25, the control device 10 calculates at least one value or parameter for actuating the syringe 3. For example, a suitable velocity v and / or a suitable force F for actuating the piston 6 can be calculated. This is done based on the current intraocular pressure piop actual and the specified pressure gradient Ap, for example, according to a previously described calculation. The control device 10 sends corresponding input values ​​to an actuating device for the piston 6, for example, a stepper motor. A control method or a regulation method can be used for this.

[0054] In step 26, the injection syringe 3 is actuated by the actuator according to the transmitted input values. The pressure sensor 14 in the cannula 4 detects the current pressure in the cannula p. C annuia and transmits this value to the control device 10. In step 27, the control device 10 adjusts the input value for the actuating device of the piston 6, for example a stepper motor, based on the set intraocular pressure piop and / or the current intraocular pressure piop actual, the specified pressure gradient Ap and the measured pressure in the cannula pcannuia.

[0055] Steps 25-27 can then be repeated. Alternatively, all steps 21 to 27 can be repeated. The described steps can also be performed in a different order or partially simultaneously. For example, step 24 can be performed before or at the same time as step 21. List of reference symbols:

[0056] 1 eye

[0057] 2 infusion lines

[0058] 3 syringes

[0059] 4 cannulas

[0060] 5 cylindrical cavity

[0061] 6 pistons

[0062] 7 Direction of movement

[0063] 8 cylindrical hollow bodies

[0064] 9 Flow direction

[0065] 10 Control device

[0066] 11 Connection for data transmission

[0067] 12 Pressure sensor

[0068] 13 Connection for data transmission

[0069] 14 Pressure sensor

[0070] 15 Arrangement for injecting a fluid

[0071] 16 Bleb

[0072] 21. Set intraocular pressure

[0073] 22 Measure current intraocular pressure

[0074] 23 set the specified intraocular pressure

[0075] Specify 24 pressure gradients

[0076] Calculate 25 operating parameters of the syringe (v and / or F)

[0077] 26. Operate the syringe and measure the current pressure in the cannula.

[0078] 27 Adjusting the input value

Claims

Patent claims 1. Control device (10) for controlling and / or regulating an injection pressure of a fluid and an intraocular pressure when injecting the fluid at an injection site between two tissue layers of the human eye (1), characterized in that the control device (10) includes a control or regulating unit designed to control or regulate the injection pressure and the intraocular pressure in such a way that the gradient between the injection pressure and the intraocular pressure assumes a predetermined value.

2. Control device (10) according to claim 1 , characterized in that the control device (10) comprises a device for determining the current injection pressure (14) and / or a device for determining the current intraocular pressure (12), which are connected to the control or regulating unit for data transmission (11 , 13).

3. Control device (10) according to claim 1 or 2, characterized in that the control device (10) is designed for controlling and / or regulating the injection pressure by controlling and / or regulating an actuating device (6) of an injection syringe (3).

4. Control device (10) according to one of claims 1 to 3, characterized in that the control device (10) is designed for continuous control and / or regulation of the gradient, and / or the control device (10) is designed for control and / or regulation of the gradient depending on the injected volume of the fluid.

5. Control device (10) according to one of claims 1 to 4, characterized in that the control device (10) includes a user interface which is designed for entering predetermined values ​​of the gradient and / or intraocular pressure and / or permissible ranges of the intraocular pressure and / or injection pressure.

6. Arrangement (15) for injecting a fluid at an injection site between two tissue layers of the human eye (1) comprising - a microinjection syringe (3), - an actuating device (6) for actuating the microinjection syringe (3), - a device for adjusting intraocular pressure (2), characterized in that - the arrangement (15) comprises a control device (10) for controlling and / or regulating the injection pressure of the fluid and the intraocular pressure when injecting the fluid according to one of claims 1 to 5, which is functionally connected to the actuating device (6) for actuating the microinjection syringe (3) and the device for adjusting the intraocular pressure (2).

7. Arrangement for performing ophthalmic operations, comprising an arrangement (15) for injecting a fluid according to claim 6.

8. Computer program for controlling and / or regulating an injection pressure of a fluid and an intraocular pressure when injecting the fluid at an injection site between two tissue layers of the human eye (1), which includes instructions which, when executed on a computer, cause it to control and / or regulate the injection pressure and the intraocular pressure such that the gradient between the injection pressure and the intraocular pressure assumes a predetermined value.

9. Non-volatile, computer-readable storage medium containing instructions for controlling and / or regulating a Injection pressure of a fluid and intraocular pressure when injecting the fluid at an injection site between two tissue layers of the human eye (1), which, when executed on a computer, cause it to control and / or regulate the injection pressure and the intraocular pressure such that the gradient between the injection pressure and the intraocular pressure assumes a predetermined value.

10. Method for controlling and / or regulating an injection pressure of a fluid and an intraocular pressure when injecting a fluid at an injection site between two tissue layers of the human eye (1) , characterized in that the method comprises the following steps: Determining the current intraocular pressure (21, 22), Specifying a target value (24) of the gradient between intraocular pressure and injection pressure, Determining the current injection pressure (26), Controlling and / or regulating the gradient (27) during injection by controlling and / or regulating the injection pressure (25) and / or the intraocular pressure (23) so that the specified target value of the gradient is achieved.

11. Method according to claim 10, characterized in that the injection pressure is controlled and / or regulated by controlling and / or regulating an actuating device (6) of an injection syringe (3).

12. Method according to claim 10 or 11, characterized in that the current injection pressure is determined by means of a sensor (14) and / or based on a detected force acting on the piston of the injection syringe and / or a detected force acting on the piston of the injection syringe pressure and / or a determined speed of movement of the piston in relation to the injection syringe is determined, and / or the current intraocular pressure is detected by means of a pressure sensor (12) of an infusion device (2) of a vitrectomy device.

13. Method according to one of claims 10 to 12, characterized in that a target value of the intraocular pressure is specified (21) and the specified target value of the intraocular pressure is set before and / or during the injection.

14. Method according to one of claims 10 to 13, characterized in that the intraocular pressure is adjusted when at least one predetermined condition is met.

15. Method according to one of claims 10 to 14, characterized in that the gradient is continuously controlled and / or regulated, and / or the gradient is controlled and / or regulated depending on the injected volume of the fluid, and / or the gradient is kept constant or within a defined range / interval / between an upper and a lower limit.

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