57 results about "Arachnoid Membrane" patented technology

A CSF management method for use with a patient forms a closed loop CSF circuit between two points on the patient's body. The CSF circuit has a therapeutic inlet to receive a therapeutic material (e.g., a drug), and a pump having a pump outlet to direct CSF along the CSF circuit. The method controls the pump to direct CSF from the pump outlet at a CSF rate that is different from the natural flow rate (i.e., the natural CSF flow rate). The therapeutic material is added to the CSF via the therapeutic input at a therapeutic rate. The CSF rate is different than the therapeutic rate and / or may be greater than the therapeutic rate. Alternative methods may control a bolus drug infusion to localize the application to a target region.

The application discloses a lumbar puncture auxiliary mechanism and a use method thereof. The lumbar puncture auxiliary mechanism comprises a main body assembly, a supporting shell fixed to one side of a positioning disc, and a puncture needle penetrating through the positioning disc and the supporting shell. The main body assembly is provided with an adjusting assembly in the supporting shell. The adjusting assembly comprises a driving element arranged on one side of the positioning disc, a transmission element arranged on one side of the driving element, and an adjusting element arranged on one side of the transmission element. The adjusting element comprises a limiting shell fixed to the inner wall of the supporting shell, a rack sliding in the limiting shell, and a first spring fixed to the end of the rack. The adjusting assembly can intermittently supply the puncture needle, so that the puncture needle can smoothly break through the yellow ligament without improper force. The puncture process can be judged, so that the time when the puncture needle enters the epidural space and the subarachnoid space can be accurately grasped, and the accidental damage to the human body is reduced.

The present disclosure is directed to neural interface devices and methods that accesses the subarachnoid space to enable minimally invasive modulation and recording of neural structures. Exemplary embodiments may comprise an implantable pulse generator and a microelectrode catheter. In particular embodiments, the microelectrode catheter comprises one or more stimulating and recording electrodes. Exemplary embodiments may also include methods comprising performing a lumbar puncture to access the spinal subarachnoid space and advancing microcatheter through the spinal subarachnoid space.

This utility model discloses an anesthesia puncture needle, including an outer needle tube and a needle hub connected to one end of the outer needle tube; it also includes an inner needle body nested inside the outer needle tube, with one end extending to the outside through the opening of the outer needle tube, and the other end extending into the needle hub. The protruding end of the inner needle body is conical, and at least one collection hole is opened on its outer wall near the end. This utility model relates to the field of medical anesthesia technology. This anesthesia puncture needle, through the cooperation of the inner needle body and the outer needle tube, can facilitate the puncture needle to enter the subarachnoid space. At the same time, it can pull the piston collector to draw cerebrospinal fluid from the end of the inner needle body and store it in the internal cavity of the piston collector, so that it can be mixed with the colorimetric solution injected through the colorimetric branch tube, thereby enabling colorimetric treatment of the cerebrospinal fluid, facilitating rapid diagnosis by medical personnel. In this process, the colorimetric solution will not come into contact with the human body, avoiding harm to the human body.

This invention relates to the field of microfluidic chip technology, specifically to a dynamic microfluidic chip device, its preparation method, and its applications for studying CAR-T therapy for gliomas. The preparation method includes: fabrication of the microfluidic chip; reconstruction of neural tissue; reconstruction of the blood-brain barrier; and simulation of the glioma microenvironment. The dynamic microfluidic chip device includes a microfluidic chip; the microfluidic chip includes, from left to right, a vascular channel, a brain parenchyma channel, a tumor channel, and a subarachnoid channel; each of the vascular channel, brain parenchyma channel, tumor channel, and subarachnoid channel includes a cell culture chamber with an inlet on one side; the cell culture chambers of the vascular channel and the subarachnoid channel have corresponding outlets on the other side. The applications include: CAR-T cell infusion; observation of transmembrane migration; and detection of biomarkers. This invention, through the dynamic microfluidic chip device, its preparation method, and its applications, aims to achieve more accurate in vitro evaluation of CAR-T cell therapy.

The invention relates to a device (1) for draining cerebrospinal fluid, wherein the device (1) has a shaft (2) that can be implanted into a skull bone (14) of a human or animal, wherein the device (1) is suitable for draining cerebrospinal fluid from the subarachnoid space and / or a cerebral ventricle (15) into the diploë of the skull bone (14), and the shaft (2) has radially extending outlet openings (4), wherein a valve (17) is arranged inside the shaft (2) which connects a first chamber to a second chamber, wherein the second chamber has a fluid connection with the outlet openings (4), and a tube (5) opens into the shaft (2) at the distal end face of the shaft (2), or a tube (20) is arranged at the distal end face of the shaft (2) to which a tube (5) is connected.wherein the tube (5) in its proximal section or the pipe (20) is in fluid communication with the first chamber and the tube (5) has at least one distal inlet opening (8) for cerebrospinal fluid, wherein the inlet openings (8) can be placed in the subarachnoid space and / or in the region of a cerebral ventricle (15) and the tube (5) has a lumen (9) into which a wire (6) can be inserted, wherein the wire (6), when inserted, protrudes from the proximal end face of the device (1). The invention allows the treating physician to position and adjust the device (1) according to the requirements for draining the cerebrospinal fluid into the diploë of the skull bone (14). Placement is possible under local anesthesia.

In some embodiments, disclosed herein are systems and methods of treating a patient that can include the steps of accessing the sphenopalatine fossa, and cannulating the inferior orbital fissure from the sphenopalatine fossa to access the retro-orbital space. The sphenopalatine fossa can be accessed via various routes, including percutaneously. Accessing the sphenopalatine fossa can include the step of inserting a needle-catheter system into the sphenopalatine fossa. Integrated needle-catheter systems as described herein can also be configured to access the trigeminal ganglion, epidural space, intrathecal space, and other desired anatomical locations.

The invention belongs to the field of biological medicines, and particularly relates to a medicine for treating meningeal metastasis of malignant tumors with NTRK and / or ROS1 mutations and a preparation method, and the medicine is a freeze-dried powder preparation or injection for subarachnoid space injection of NTRK / ROS1-TKIs. The invention also provides an application of the NTRK / ROS1-TKIs in preparation of a medicine for treating meningeal metastasis of malignant tumors with NTRK and / or ROS1 mutation. The prepared NTRK / ROS1-TKIs injection can be directly injected into the subarachnoid space of a patient, the drug concentration in cerebrospinal fluid of the patient is greatly improved, the cerebrospinal fluid / plasma concentration ratio can reach 20 times or more, the problem of insufficient dosage caused by the blood-brain barrier after the targeted drug is orally taken can be completely solved, and the drug has the advantages of fast effect taking, no toxic or side effect and no toxic or side effect. The treatment effect on meningeal metastasis of malignant tumors such as lung cancer can be obviously improved.

This utility model discloses a lumbar puncture needle with monitoring function, comprising: a needle body, with a puncture needle main body internally connected to the needle body. The puncture needle main body is used to detect puncture depth and monitor cerebrospinal fluid pressure. The puncture needle main body includes an outer needle and an inner needle, with the inner needle located inside the outer needle. A gap is reserved between the outer and inner needles. A signal receiving mechanism is provided at the top of the outer needle. Both the outer and inner needles are electrically connected to the signal receiving mechanism via a point-to-line connection. This utility model provides a lumbar puncture needle with monitoring function, consisting of a system and a puncture needle main body. It can issue an alarm when the puncture needle tip contacts the cerebrospinal fluid in the subarachnoid space of the lumbar spine, and can monitor the cerebrospinal fluid pressure in real time during cerebrospinal fluid collection. Through precise puncture depth feedback and real-time cerebrospinal fluid pressure monitoring, doctors can more accurately locate the puncture point, reduce surgical errors, and improve the success rate of surgery. Real-time monitoring of cerebrospinal fluid pressure helps to detect abnormal intracranial pressure in a timely manner, prevent serious complications such as brain herniation, and ensure patient safety.

The present disclosure is directed towards devices, methods, and related systems that are minutely-invasively delivered to the brain parenchyma, subdural or subarachnoid space where the devices, methods, and systems directly interface with central nervous system media (i.e., fluid or tissue) enabling detecting, sensing, measuring, stimulating, altering and / or modulating of the media or tissue surfaces.

The application discloses a method, device and equipment for evaluating the width and narrowness degree of the subarachnoid space of the optic nerve, and the method comprises the following steps: collecting a target image corresponding to a target position of the optic nerve, and obtaining the resolution of the target image, wherein the target position is any one of a plurality of preset positions on the optic nerve; dividing the subarachnoid space of the optic nerve in the target image into at least two regions by using at least one division line, the division line passes through the centroid of the optic nerve sheath in the target image, and the target circle central angle is bisected, the target circle central angle is the central angle of a circle with the centroid as the center and an arbitrary length as the radius; evaluating whether the target image meets the first evaluation standard based on the images of the at least two regions and the resolution of the target image; in this way, the defect that the MR image cannot be effectively judged whether it can be used for evaluating the width and narrowness degree of the subarachnoid space of the optic nerve can be solved, and the subarachnoid space of the optic nerve can be equally divided to the maximum extent, so that the final evaluation result is more accurate and more persuasive.

The invention belongs to the field of biological medicine, and particularly relates to a medicine for treating EGFR mutation non-small cell lung cancer meningeal metastasis, application, a medicine box and a preparation method of the medicine, the medicine is a freeze-dried powder preparation or injection of EGFR-TKIs for subarachnoid space injection, the amount of EGFR-TKIs per person in the medicine is 0.01-5 mg, and the amount of EGFR-TKIs in the medicine is 0.01-5 mg. The injection method comprises any one of lumbar puncture, bridge forebay indwelling catheter injection and Ommaya capsule injection. The prepared EGFR-TKIs injection can be directly injected into the subarachnoid space, the drug concentration in cerebrospinal fluid of a patient is greatly improved, the cerebrospinal fluid / plasma concentration ratio of the EGFR-TKIs injection is increased from far less than 1 to more than 2 times and even can reach more than 10 times, and the EGFR-TKIs injection can completely solve the problem of insufficient dosage caused by a blood-brain barrier after oral administration of a targeted drug and has a good application prospect. The medicine takes effect quickly, and the treatment effect on lung cancer meningeal metastasis can be remarkably improved.

This invention discloses a cerebrospinal fluid external filtration and dialysis device for the purification and treatment of cerebrospinal fluid in diseases such as central nervous system infections and subarachnoid hemorrhage. The device includes a dual-lumen drainage tube, comprising an outflow pipe and an inflow pipe. The outflow pipe is connected to the inlet of the filtration and dialyzer via a suction-side connecting pipe. The suction-side connecting pipe passes through a peristaltic pump and is equipped with a sampling pipe, on which a detachable timed sampler is mounted. The first outlet of the filtration and dialyzer is connected to a storage bag via a suction connecting pipe, and the second outlet is connected to the inflow pipe via a return connecting pipe. Pressure sensors are installed on both the suction-side and return connecting pipes, and a flow meter is installed on the return connecting pipe. These components form a feedback control loop with a control processor to adjust the pump speed and valve opening and closing, achieving safe and controllable flow and pressure. This device can filter / dialyze pathogens and inflammation-related substances in cerebrospinal fluid and return them, while simultaneously performing timed sampling for dynamic monitoring.

A method for the in vitro diagnosis of the risk of delayed cerebral ischemia (DCI) following subarachnoid hemorrhage from a ruptured aneurysm (aSAH) which includes the following steps: collection of a blood sample from the patient; quantitative determination of 8-iso-prostaglandin F2α (F2-IsoP) concentration in plasma; comparison of the concentration thereof in plasma with the reference value; collection of at least one further blood sample; quantitative determination of the concentration of endothelial nitric oxide synthase (eNOS) and / or nicotinamide adenine dinucleotide phosphate (NADPH) in plasma; comparison of the concentration thereof in plasma with the reference value; analysis of the obtained results and establishing diagnosis. A marker substance for the in vitro diagnosis of the risk of occurrence of DCI selected from 8-iso-prostaglandin F2α (F2-IsoP), endothelial nitric oxide synthase (eNOS), nicotinamide adenine dinucleotide phosphate (NADPH) and combinations thereof and the use thereof as a screening test for the in vitro diagnosis of DCI following aSAH.

The present invention provides a pharmaceutical composition, which is an aqueous solution containing Compound (I) (also known as U0126) or a pharmaceutically acceptable salt thereof at a concentration of 50-200 μM, further comprising 0.2-1.0% (v / v) polyoxyethylene castor oil. The composition is particularly useful in treating ischemic injury (particularly subarachnoid hemorrhage) in human patients by direct injection into the brain. Uses of the composition, unit doses containing the composition, and methods of using the composition are also disclosed. [Formula 1] TIFF2026501344000012.tif40159

The present invention provides a pharmaceutical composition which is an aqueous solution comprising Compound (I) (also known as U0126) or a pharmaceutically acceptable salt thereof at a concentration of 50 [mu] M to 200 [mu] M, and wherein the solution further comprises 0.2% to 1.0% (v / v) polyoxyethylated castor oil. The compositions are particularly useful for the treatment of ischemic injury, in particular subarachnoid hemorrhage, in human patients by direct injection into the brain. Uses of the compositions, unit doses containing the compositions and methods of using the compositions are also disclosed. # imgabs0 #

The present disclosure discusses a devices, systems and methods for transvascular, transvenous and / or transdural access, to the brain parenchyma, subarachnoid or subdural spaces. In some embodiments, the disclosed systems and methods may be used for local drug delivery, tissue biopsy, nanofluidic or microelectronic device / component delivery / insertion / implantation, in situ imaging, ablation of abnormal brain tissue and the like. Embodiments of the present disclosure include an access catheter system for extravascular procedures in the brain having an elongate, flexible tubular body, with at least one lumen extending axially there through between a proximal end, and a distal end. The access catheter system may include a side exit port and a distal end port. Further, the access catheter system may include a selective deflector positioned within the lumen configured to deflect a procedure catheter and permit a guide catheter.

Provided is a pharmaceutical composition with which it is possible to prevent the development of late-onset cerebral ischemia and obtain a prognosis-improving effect by performing active hematoma removal using a tissue plasminogen activator. This pharmaceutical composition contains a tissue plasminogen activator as an active ingredient and is for use in hematoma removal therapy in the cerebral cistern to remove a dislodged hematoma by suction by using the tissue plasminogen activator in an aqueous solution state as a cleansing agent, said therapy being performed at the same time as treatment of a cerebral aneurysm by means of craniotomy with clipping during the acute phase of a subarachnoid hemorrhage associated with a ruptured cerebral aneurysm.

The invention relates to a device (1) for draining cerebrospinal fluid, wherein: the device (1) comprises a shaft (2) which can be implanted into a cranial bone (14) of a human or animal; the device (1) is suitable for draining cerebrospinal fluid from the subarachnoid space and / or a cerebral ventricle (15) into the diploe of the cranial bone (14), and the shaft (2) has outlet openings (4) pointing in the radial direction; a valve (17) is arranged in the interior of the shaft (2) and connects a first chamber (21) to a second chamber (22); the second chamber (22) is fluidically connected to the outlet openings (4), and a tube (5) joins the shaft (2) at the distal end face of the shaft (2) or a conduit (20) to which a tube (5) is connected is arranged on the distal end face of the shaft (2); the tube (5), in its proximal portion, or the conduit (20) is fluidically connected to the first chamber (21), and the tube (5) distally has at least one inlet opening (8) for cerebrospinal fluid; the inlet openings (8) can be placed in the subarachnoid space (6) and / or in the region of a cerebral ventricle (15), and the tube (5) has a lumen (9) into which a wire (6) can be introduced; the wire (6), in the introduced state, protrudes from the device (1) at the proximal end face thereof. The invention allows the treating doctor to place and adjust the device (1), according to requirements, in order to conduct the cerebrospinal fluid into the diploe of the cranial bone (14). Placement is possible under local anaesthesia.

The invention provides a construction method of a spinal cord injury animal model for maintaining the integrity of subarachnoid space, which comprises the following steps: adopting a mammal with spinal cord injury, clamping and closing the opening of the dura mater of the mammal, dripping biological glue in alignment with the clamped and closed position, and suturing after the biological glue becomes frost and the dura mater is adhered together. The invention also provides application of the spinal cord injury animal model for maintaining the integrity of the subarachnoid space in research on motor function, nervous tissue recovery or tissue morphology recovery of animals after spinal cord injury. The application shows that after experimental spinal cord injury is caused, the motion function and histomorphological recovery of a mouse can be improved by tightly suturing the dura mater.

The subject invention pertains to a novel causal effect estimation approach for aneurysmal subarachnoid hemorrhage treatment and treatment related decision support based on multi-modality imaging and non-imaging clinical data. The provided embodiments are shown to effectively estimate the treatment effect; and to utilize multi-modality data to perform this estimation. Embodiments provide a novel scheme that uses multi-modality confounders distillation architecture to predict the treatment outcome and treatment assignment simultaneously. The distilled confounder features provide an imaging and non-imaging interaction representation learning strategy to use the complementary information extracted from different modalities to balance the representation distribution of different treatment groups. Extensive experiments have been performed on a subarachnoid hemorrhage clinical dataset, which is collected from the Hospital Authority Data Collaboration Lab and contains 656 cases. The provided method shows consistent improvements on the evaluation metrics of treatment effect estimation, achieving state-of-the-art results over related art competitors.

The utility model relates to the technical field of anesthetic needles, and discloses a low-damage easy-to-puncture subarachnoid space anesthetic needle, which comprises a lumbar anesthesia needle main body, the lumbar anesthesia needle main body comprises a main needle body and a needle tip, the needle diameter of the main needle body ranges from 0.5 mm to 0.8 mm, the needle diameter of the main needle body is 0.7 mm, the length of the main needle body is 50mm, the length of the needle tip is 5mm, the needle diameter of the needle tip is 0.3 mm, and the needle tip of the main needle body is 0.5 mm. The needle diameter of the needle tip ranges from 0.3 mm to 0.5 mm, and the needle tip is designed to be provided with an inclined opening. On the basis of a traditional lumbar anesthesia needle, the needle point part of the lumbar anesthesia needle is improved, so that the needle point part is specially refined, the advantages of the traditional lumbar anesthesia needle and the specially-refined lumbar anesthesia needle are combined, the puncture smoothness can be guaranteed, leakage of cerebrospinal fluid can be reduced, and the occurrence rate of postoperative anesthesia headache can be prevented.

The invention relates to the technical field of medical instruments, and particularly discloses a puncture outfit for subarachnoid space block anesthesia. The limiting mechanism is inserted into the guiding device; the puncture needle core seat is inserted into the limiting mechanism; through the arrangement of a mounting plate, a coil spring, a limiting plate and a winding wheel, when an operator pushes a limiting insertion rod, the limiting insertion rod breaks away from the limiting effect on the limiting plate, at the moment, elastic potential energy stored between the winding wheel and the coil spring is released, and the winding wheel starts to automatically and rapidly rotate under the driving of torsional force of the coil spring; by means of the automatic winding mechanism, the stabbing injury risk caused by accidental falling or collision of the needle core is fundamentally eliminated, reliable safety protection is provided for medical staff, and occupational exposure hidden dangers are remarkably reduced.

The invention relates to an anchoring mechanism and a device for percutaneous interventional therapy of hydrocephalus, the device comprises a shunting unit, the shunting unit comprises a shunting tube body, a one-way valve and an anchoring mechanism, the anchoring mechanism comprises a fixing part and an anchoring rod, one end of the anchoring rod is connected with the fixing part, the other end of the anchoring rod is a free end, and the anchoring mechanism is connected with the other end of the anchoring rod in an anchoring state. And the anchoring rod deviates relative to the fixed part, or the anchoring rod deviates from the shunting pipe body, so that a space for anchoring is formed. The invention provides a brand new anchoring mechanism which does not relate to an expansion structure, so that the volume of the device in the subarachnoid space can be reduced, and the intracranial occupation is reduced; the device can be used for treating hydrocephalus through an intervention method, open surgical operation is not involved, trauma is reduced during operation, surgical operation time is saved, the contact area of the device and blood is reduced, and therefore the risk of central nervous system injury and blood-related complications is reduced; and the possibility of postoperative infection can be greatly reduced by matching with an anchoring mechanism.

Systems and methods for implanting an endovascular shunt in a patient is disclosed. The system having an expandable anchor configured for being deployed in a dural venous sinus of a patient at a location distal to a curved portion of a wall of an inferior petrosal sinus (IPS) of the patient; an elongate guide member coupled to, and extending proximally from, the anchor; a shunt delivery catheter having a first lumen configured to receive the guide member, and a second lumen extending between respective proximal and distal openings in the shunt delivery catheter, the shunt delivery catheter further having a penetrating element coupled to a distal end of the catheter; and the system further having a guard at least partially disposed over, and movable relative to, the penetrating element.

The utility model discloses a novel lumbar puncture needle, and relates to the technical field of lumbar puncture needles. The syringe comprises a needle tube used for puncture operation, and the tail end of the needle tube is connected with a first duckbilled silica gel one-way valve; the needle core can be inserted into the needle tube and is used for puncturing, a groove is formed in the surface of the needle core, and cerebrospinal fluid can flow out through the groove. Due to the design that the groove is formed in the surface of the needle core, cerebrospinal fluid can still flow out through the groove even if the needle core is completely inserted into the needle tube, so that a doctor can immediately judge whether the cerebrospinal fluid flows out or not and confirm whether the needle core correctly enters the subarachnoid space or not. By means of the design, operation is greatly simplified, the step of repeatedly pulling out the needle core is reduced, the efficiency and accuracy of the puncture process are improved, and discomfort of a patient is reduced.

The invention relates to the technical field of augmented reality medical training, in particular to a subarachnoid space puncture training system based on augmented reality, which comprises a scene loading module, a process control module, a visualization processing module, a synchronous explanation module and an interaction control module. The system loads a three-dimensional anatomical or panoramic video training scene according to the selection of a user, and starts a four-stage progressive training process. And carrying out transparency gradient processing on the three-dimensional human body model through material rendering control, and dynamically generating an anatomical structure visualization effect from the skin to the deep tissue. And the synchronous explanation module activates the dynamic annotation system, displays the corresponding anatomical annotation according to the training stage, and synchronously plays voice explanation and subtitles based on the time axis. The interaction control module responds to the user operation instruction and controls the playing state of the training process. According to the system, progressive visualization of an anatomical structure and accurate and synchronous explanation of training content are realized, and the immersion, coherence and teaching effect of training are improved.

The invention discloses a syringomyelia-subarachnoid space shunt tube, and relates to the technical field of syringomyelia surgery, the syringomyelia-subarachnoid space shunt tube comprises a first assembly and a second assembly, the first assembly comprises an embedding part and a leading-out part, the embedding part is communicated with the interior of the leading-out part, and the embedding part is fixedly connected with the leading-out part; sieve holes are formed in the embedding part and the leading-out part, and the end parts of the embedding part and the leading-out part are closed; and the second assembly can be sleeved on the surface of the lead-out part to change the shape of the first assembly. By arranging the second assembly, the h-shaped shunt tube is formed after combination, surgical implantation is facilitated, meanwhile, stress is prevented from pressing peripheral spinal cord tissue when the tube is bent, the position of the second assembly is adjustable, the second assembly can be individually placed according to the thickness of a syringomyelia wall, in addition, the tail end of the tube is closed, sieve holes are formed, and tissue debris is prevented from entering the tube to cause blockage.

Disclosed herein are methods and systems configured to distribute multiple fluids towards a target area. The target area may comprise a nerve ending within a patient's intrathecal space retaining cerebrospinal fluid (CSF). At least one fluid of the multiple fluids may be a therapeutic fluid comprising a medication. The distribution may be controlled to adjust a baricity of the therapeutic fluid with respect to the CSF, to provide more effective distribution towards the target area. An implementation may consider fluid densities, fluid flow rates, relative position and spatial orientation of the target area with respect to a point of fluid distribution to determine and control the fluid distribution toward the target area. An implementation may individually adjust fluid flow rates from multiple reservoirs to adjust therapeutic fluid baricity, dynamically modulate fluid extraction and aspiration through the intrathecal space using barbotage and respond to device or patient spatial orientation, permitting precise therapeutic fluid distribution prescriptions.

A shunt 200 for treating glaucoma in a patient during and / or after vitreoretinal surgery involving the use of a tamponading agent comprising a gas or oil bubble 50. The shunt includes a tubular body 12 having a proximal end 14 which is implantable in the vitreous cavity C of a patient and a distal end which is implantable in the subarachnoid space of the patient. The tubular body defines a lumen 18 extending between the distal and proximal ends. The shunt includes an occlusion body 32 defining a number of micro-passages 34 inflow communication with the lumen 18. The micro-passages are configured in terms of their size and number to provide sufficient surface tension and viscosity resistance in order to prevent the tamponading agent from passing through the micro-passages into the lumen, yet allow sufficient aqueous fluid from the vitreous cavity to travel along the micro-passages into the lumen 18 in order to regulate intraocular pressure.