Surgical assemblies for ocular surgery, systems and methods of compensation of intraocular pressure

Abstract

Surgical assemblies for ocular surgery are provided. Such assemblies include direct measuring devices of intraocular pressure, surgical accessories utilisable in conjunction with a surgical instrument suitable for performing eye surgery, such surgical accessories being insertable in an ocular cavity through an accessory ocular incision. Direct measuring devices of intraocular pressure may be coupled to the surgical accessories so as to be insertable in the ocular cavity along with said surgical accessories through said accessory ocular incision.

Claims

1. A direct measurement method of intraocular pressure during eye surgery, the method comprising using a surgical accessory in conjunction with a surgical instrument; the surgical instrument suitable for being inserted in an ocular incision of a cavity of the eye made by the surgical instrument for performing the eye surgery, wherein the surgical accessory comprises a pressure transducer, an endoilluminator device and an attachment guide ring and wherein said surgical accessory is insertable in the cavity of the eye through an accessory ocular incision, different from said ocular incision made by the surgical instrument, and wherein the pressure transducer and the endoilluminator are inserted in the accessory ocular incision side by side with interference in the attachment guide ring, the attachment guide ring being positioned at a predetermined distance from distal ends of the pressure transducer and the endoilluminator.

2. The method of claim 1, wherein the endo-illuminator device is configured to illuminate a field of surgery or an infusion cannula of an infusion system suitable for injecting an irrigation fluid to compensate the intraocular pressure.

3. The method of claim 1, wherein said accessory ocular incision has a maximum size of 0.5 mm.

4. The method of claim 1, wherein the surgical accessory further comprises a positioning cannula adapted to be placed in the accessory ocular incision; the positioning cannula having a flange, wherein the attachment guide ring is configured to abut the flange of the positioning cannula so as to determine the insertion depth of the pressure transducer and the endoilluminator in the cavity of the eye.

5. A compensation method of the intraocular pressure during eye surgery, comprising the steps of: performing the direct measurement of the intraocular pressure by the method of claim 1, comparing the intraocular pressure measured with a tolerable intraocular pressure range, if said intraocular pressure measured has a value greater than a predetermined maximum intraocular pressure value, generating an alarm or, if a vitreous is not present inside the cavity of the eye, activating a pump to aspirate an intraocular fluid; if the value of said intraocular pressure measured is lower than a predefined minimum intraocular pressure value, activating an infusion pump to introduce an amount of infusion fluid in the cavity of the eye.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a surgical assembly according to the invention, in an embodiment comprising a measuring device of the pressure coupled to an endoilluminator;

(2) FIG. 2 shows the surgical assembly of the previous figure inserted in a valved cannula;

(3) FIG. 3 shows a surgical assembly according to the invention, in an embodiment variant comprising a measuring device of the pressure coupled to an infusion cannula;

(4) FIGS. 4 and 4a show, in elevation and in axial cross-section, the surgical assembly of the previous figure inserted in a valved cannula;

(5) FIG. 5 shows the surgical assembly of the previous figure connected to a three-way valve;

(6) FIG. 6 shows the surgical assembly of FIG. 2 inserted in the vitreous chamber of the eyeball;

(7) FIG. 7 shows the surgical assembly of FIG. 5 inserted in the anterior chamber of the eyeball;

(8) FIG. 8 is a block diagram of a compensation system of ocular pressure in vitrectomy surgery;

(9) FIG. 9 is a block diagram of a compensation system of ocular pressure in a cataract operation or trabulectomy;

(10) FIG. 10 is a flowchart of a control algorithm of intraocular pressure; and

(11) FIG. 11 is a flowchart of a control algorithm of intraocular pressure in an alternative embodiment.

DETAILED DESCRIPTION

(12) In some embodiments, the surgical assembly consists of three modules, combined as described below. The three modules have the following functions: direct measurement of intraocular pressure, illumination and infusion of fluids. Advantageously, the surgical assembly according to the invention uses a single ocular incision for the contemporary insertion of two different modules, coupled according to the specific requirements for the various surgical operations. This approach makes it possible to integrate in a single device both the basic functionality required during eye surgery, such as lighting or infusion, and functions not found in current surgical instruments, such as the direct measurement of intraocular pressure changes, requiring a single ocular incision of limited size. Hereafter, such ocular incision will also be referred to as accessory incision to distinguish it from the incision through which the surgical tool itself operates.

(13) For example, the assembly according to the invention provides for a single accessory ocular incision made by using a needle with external diameter of not more than 0.5 mm, in order to reduce postoperative complications of surgery and speed up patient recovery.

(14) A first module used to obtain the surgical assembly according to the invention is the pressure detector 10, i.e. a miniaturised pressure transducer for the direct measurement of intraocular pressure.

(15) In advantageous embodiments, the pressure detector 10 is a fiber optic transducer which transmits the pressure signal obtained from the deflection of a diaphragm in the form of a variation in the intensity of the light reflected through a fiber optic. The advantages of this type of transducer are related to its small dimensions and the absence of voltages for signal transmission. A commercial example of a fiber optic pressure transducer is the product Fiber Optic Pressure Sensor OPP-M25 manufactured by Opsens (Quebec, Canada). This sensor has an outside diameter of 0.25 mm and a measuring accuracy of 2 mmHg in a range of pressures from 30 to +300 mmHg. The pressure detector 10 is connected to a conditioning unit 12 (shown schematically in FIGS. 8 and 9) for capturing and amplifying the pressure signal at a frequency up to 250 Hz.

(16) A second module used to obtain an assembly according to the invention comprises an endoilluminator 20, needed in vitrectomy operations to illuminate the field of surgical action. The lighting can be obtained either through fiber optic systems which can be directed by the surgeon depending on the ocular area of interest, or by means of chandelier probes inserted in the eye cavity in a fixed position and anchored to the outer surface of the sclera with a special guide.

(17) The invention provides, in particular, for the use of lighting systems with a diameter not exceeding 0.25 mm to be compatible with the size of the needle and the pressure detector. For example, the fibre contained in the chandelier Oshima Dual of Synergetics (O'Fallon, Mo.) may be used.

(18) A third module which can be used to obtain an assembly according to the invention has an infusion system 30 needed to compensate the depression measured by the measuring device. This module includes a reservoir 32 containing the irrigation fluid, such as a physiological saline solution compatible with the intraocular fluid. In some embodiments, an infusion pump 34 is also present, such as a positive displacement or syringe pump, such as, for example the Alaris products of CareFusion Corporation (San Diego, Calif., USA), or a peristaltic pump, such as the one marketed by the Watson-Marlow company, which reaches flow rates up to 1200 ml/h. The infusion pump 34 is connected to the reservoir of fluid through an input line while it regulates the amount of fluid on the output line needed to compensate the pressure variations measured.

(19) In some embodiments, the infusion pump 34 or an additional pump, is suitable to operate in aspiration to aspirate intraocular fluid and can be fluidically connected to a second collection reservoir of the aspirated fluid.

(20) In the case in which vitrectomy surgical instruments 100 provided with an infusion line 102 (FIG. 8) are present, the output line of the infusion pump can be connected to a battery of taps 36 presents on the infusion line 102 of the surgical instrument 100, for example a vitrectome, by a three-way valve. In this case, as will be described below in more detail, the pressure detector 10 is coupled to the endoilluminator 20.

(21) In the event that there is no surgical instrument with an infusion line (FIG. 9) present, a connection via a three-way solenoid valve 40 of the output line of the pump 34 to an infusion cannula 50 may be provided for. In this case, the pressure detector 10 is coupled to the infusion cannula 50.

(22) FIG. 1 shows a surgical assembly according to the invention in an embodiment which provides for the combined use of the first and second modules. An optic fiber pressure transducer 10 is coupled to an endoilluminator 20. The two devices side by side are inserted with interference in an attachment guide ring 12. Said attachment guide ring 12 is positioned at a predetermined distance from the ends of the pressure transducer 10 and the endoilluminator 20.

(23) FIG. 2 shows the surgical assembly 1 inserted in a positioning cannula 5, for example a valved cannula, suitable to be placed in the eye cavity.

(24) In the rest of the description, a valved cannula is understood to mean a positioning cannula fitted with a valve at the end to prevent the leakage of fluids from the ocular incision. The use of a valved cannula is particularly advantageous to be able to work and measure pressure in a closed circuit.

(25) As may be noted, the attachment guide ring 12 abuts with the flange 6 of the positioning cannula 5, so as to establish the depth of insertion of the pressure transducer 10 and endoilluminator 20 inside the eye cavity 200, as shown in FIG. 6.

(26) FIG. 3 shows a surgical assembly 2 according to the invention in an embodiment which involves the combined use of the first and third module. In particular, the fiber optic transducer 10 is inserted coaxially in an infusion cannula 50. The latter comprises a distal portion 50 suitable to be inserted in the eye cavity and a proximal cylindrical portion 50 suitable to abut with the flange 6 of the positioning cannula 5 for example a valved cannula. The distal portion 50 of the infusion cannula 50 and a distal portion of the transducer 10 are inserted in the positioning cannula as shown in FIG. 4.

(27) For example, as the infusion cannula 50, a high-flow cannula of the type sold by the company D.O.R.C. International may be used.

(28) In one embodiment, the pressure detector is inserted with interference in an attachment guide ring 12 co-operating with the infusion cannula 50 so as to determine the position of the distal end of the transducer 10 relative to the distal end of the infusion cannula 50.

(29) In one embodiment shown in FIG. 5, the pressure detector 10 and infusion cannula 50, with the respective ends inserted in the positioning cannula 5 are connected to each other by a three-way valve 40. A first way 41 is fluidically connected to the infusion cannula 50; a second way 42, aligned with the first, is connected to the pressure detector 10; a third way 43 is fluidically connected to the output line of the infusion pump 34. The attachment guide ring 12 in this case acts in conjunction with the entrance of the second way 42 of the valve 40 to lock the axial position of the pressure detector 10.

(30) FIG. 8 is a block diagram of a compensation system of intraocular pressure in a case of vitrectomy surgery, which uses the surgical assembly 1 composed of the pressure transducer 10 and the endoilluminator 20. The endoilluminator 20 is operatively connected to a light source 22 and is inserted, along with the pressure detector 10 in a positioning cannula 5 positioned in the eyeball 200.

(31) The pressure detector 10 is operatively connected to a conditioning unit of the signal 14, which in turn communicates with a control unit 16 of the compensation system. The control unit 16 controls the operation of an infusion pump 34 and a tap with solenoid valve 36 connected to an infusion cannula 102 of the surgical instrument 100, in this case the vitrectome. The infusion pump 34 is suitable to aspirate the infusion fluid from a reservoir 32 and is connected in output to the tap with solenoid valve 36 of the infusion cannula 102.

(32) FIG. 9 illustrates instead a pressure compensation system in the case of intraocular cataract surgery or trabeculectomy. The compensation system uses the surgical assembly 2 composed of the pressure detector 10 and the infusion cannula 50, for example in the connection configuration using the three-way valve 40. In this case, the control unit 16 controls, in addition to the infusion pump 34, the tap with three-way valve 40 to which the infusion cannula 50 is connected.

(33) In one embodiment shown in the flow chart in FIG. 10 relative to a compensation algorithm 300 of intraocular pressure, the control unit 16 processes the pressure signal acquired from the transducer (step 302) and compares the pressure value measured with a range of tolerable pressures (steps 304 and 306). Based on the outcome of this comparison, the control unit 16 sends appropriate control signals according to two modes of operation. In the basic mode, the control unit supplies an alarm signal in the form of visual or auditory feedback to the surgeon in the case in which pressure variations are recorded outside the tolerable range (step 308). The possibility of activating the alarm signal only if the pressure values are below threshold or above threshold for a time interval greater than that allowed may also be provided for.

(34) In an optional mode of operation, it instead provides for a compensation in line of the intraocular depressions through automatic or on-demand infusion by the surgeon. In this mode, in the case in which decreases in intraocular pressure below the established threshold are recorded (step 306) the control unit activates the infusion pump in order to compensate for pressure changes automatically or at the surgeon's request (step 310).

(35) The flowchart in FIG. 11 illustrates a compensation algorithm 400 of intraocular pressure according to an embodiment variant.

(36) The control unit 16 processes the pressure signal acquired by the transducer (step 402) and compares the pressure measured with a tolerable pressure range (step 404). If the pressure measured is not within the tolerable range, and if the control unit 16 operates in a basic mode, the control unit 16 provides an alarm signal in the form of visual or auditory feedback to the surgeon (step 406). The possibility of activating the alarm signal only if the pressure values are below threshold or above threshold for a time interval greater than that allowed may also be provided for.

(37) If the control unit 16 operates in an active control mode and if the pressure is below the minimum threshold (step 408), the control unit 16 activates the pump 34 in infusion to compensate the pressure changes automatically or at the surgeon's request (410).

(38) If the measured pressure exceeds the maximum pressure allowed, and if the vitreous body is not present in the eye, (step 412), then the control unit 16 activates the pump to aspirate the intraocular fluid (step 414).

(39) If instead the vitreous body is present inside the eye, then it simply generates the alarm signal (step 406).

(40) If the vitreous body is present in the eye, in fact, aspiration of the vitreous body should be avoided so as not to cause detachment of the retina.

(41) It is to be noted that, in the case of the pressure compensation procedure providing for aspiration of the intraocular fluid, a special reservoir may be provided which collects the aspirated fluid so as to not contaminate the irrigation fluid.

(42) Moreover, when the pump 34 is active, in infusion or aspiration, the infusion through the vitrectome can be disabled by means of the tap with solenoid valve 36.

(43) Examples of use of the intraocular pressure compensation systems described above will now be given.

(44) Depending on the type of ocular surgery, several possible application scenarios of the invented device are provided for.

(45) As mentioned above, in the case of vitrectomy (FIGS. 6 and 8), the modules inserted in the eye cavity by means of the positioning cannula are represented by the pressure detector 10 and the endoilluminator 20. The output line of the infusion pump 34 is connected to the infusion line 102 of the surgical instrument 100, thus using an access point for the infusion of fluid different from the point of pressure measurement. In the case of measuring increases in pressure, caused for example by indentation or infusion of external fluids, a visual or audible alarm is activated to alert the surgeon and cause him/her to decrease the indentation or the infusion pressure to compensate for the pressure increases.

(46) In a variant described above, in the event of pressure increases automatic aspiration of intraocular fluid by the pump is also possible if the vitreous body is not present in the eye.

(47) In the case in which intraocular depressions are recorded, related for example to the fragmentation and aspiration of tissue, depending on the selected mode of operation the device provides the warning signal or activates the infusion pump and the solenoid valve to which it is connected, to infuse saline solution in the eye cavity and maintain pressure within the acceptable range.

(48) Trabeculectomy and cataract operations (FIGS. 7 and 9) do not require instead any intraocular illumination system. In this scenario, the modules used are the pressure detector 10, such as the fiber optic transducer, and the infusion system 30. The optic fiber pressure transducer 10 is inserted in the infusion cannula 50 connected to the positioning cannula, to which the output line of the infusion pump is also connected. In the case in which decreases in intraocular pressure below the set value are detected, following for example an excessive outflow of aqueous humour from the anterior chamber of the eye, the device activates the alarm signal or the infusion pump in order to restore the pressure values within the safe range.

(49) With regard to compensation of the intraocular pressure, it must be specified that during vitrectomy surgery in some cases the step of fluid infusion is interrupted by the surgeon and an infusion into the vitreous cavity of air is performed. In this case, the pressure detector continues to operate independently of the administration of fluids or air. In case of exceeding a minimum pressure threshold, the pressure compensation system provides for the intervention of the infusion pump to restore the pressure above the minimum threshold. Since the surgeon is operating while infusing air and the ingress of fluid in the vitreous chamber is not allowed in that it would damage surgery, the solenoid valve which opens the infusion circuit controlled by the infusion pump can no longer be controlled, but another way is opened connected to the external control unit and/or connected to the surgical instrument (in this case the phaco/vitrectome) for the introduction of air.

(50) Therefore, depending on the phase of surgery, the control unit controls the infusion system to infuse air at a controlled pressure or saline solution contained in the reservoir.

(51) In one embodiment, the battery of taps connected to the cannula of the surgical instrument inserted in the eyeball is provided with an input for a saline solution and an inlet for the air, and the air-saline switching is performed by selecting the desired input.

(52) The main advantage of the invented device compared to existing surgical instruments for eye surgery consists in the direct measurement of intraocular pressure by means of a detector inserted in the eye cavity. Unlike the indirect methods currently used, based on the measurement of the pressure or flow on the infusion/aspiration line, the direct approach permits measurement of the pressure value at any phase of surgery and not only during the operations carried out by the surgical instrument. Furthermore, the direct measurement takes into account possible variations in intraocular pressure related to external factors, such as scleral indentation or the injection of other fluids. These factors are not measured and compensated with the indirect measurement of pressure on the infusion line. The ability to monitor and compensate pressure variations occurring during eye surgery by direct measurement could potentially reduce the risks of intraoperative and postoperative complications (infection, bleeding, detachment of the retina or choroid), contributing to a more effective recovery of eyesight. These advantages would be most evident especially in patients with pathologies that compromise the perfusion of the optic nerve and the retina, who are more susceptible to intraocular pressure increases with consequent decreases in perfusion pressure.

(53) The proposed invention also has substantial benefits compared to the device of the prior art for the direct measurement of pressure using a pressure detector mounted on the surgical instrument. Such system is more invasive because it requires ocular incisions of considerable diameter. In this application, the pressure detector is instead integrated with the endoilluminator, which has smaller dimensions than the surgical instruments, thus using a single incision of limited diameter (no larger than 25 gauge). For surgical procedures where the use of endoilluminators is not necessary, such as in trabeculectomy and cataract, the pressure detector is instead integrated with the infusor, by inserting it directly in the infusion cannula to limit the size of the incision. Another advantage over the device mounted on the surgical instrument consists of the greater accuracy of pressure measurement that is carried out in regions of the eye not disturbed by the action of the surgical instrument, inserted in a different part of the eye cavity from the detector.

(54) A person skilled in the art may make modifications and variations to the embodiments of the surgical assemblies, systems and methods of compensation of intraocular pressure according to the invention, replacing elements with others functionally equivalent so as to satisfy contingent requirements described above, without thereby departing from the intended scope of protection as described and claimed herein. Each of the characteristics described as belonging to a possible embodiment may be realised independently of the other embodiments described.