WO2007006466A1

WO2007006466A1 - Device for the treatment of glaucoma

Info

Publication number: WO2007006466A1
Application number: PCT/EP2006/006552
Authority: WO
Inventors: Demetrio Romeo
Original assignee: Demetrio Romeo
Priority date: 2005-07-14
Filing date: 2006-07-05
Publication date: 2007-01-18
Also published as: EP1924229A1

Abstract

This description relates to a device for the treatment of glaucoma composed of: an aspiration cannula (19) adapted to penetrate the anterior chamber (13) of the eye to aspirate the trabecular meshwork (16) and an infusion cannula (18), associated with said aspiration cannula (19), to infuse a sterile poly-saline solution in the anterior chamber (13) of the eye, in order to maintain the original open spaces and to compensate the aspiration action on the trabecular meshwork (16).

Description

DEVICE FOR THE TREATMENT OF GLAUCOMA

DESCRIPTION

The present invention relates to a medical device for the treatment of open angle glaucoma through direct surgery on trabecular meshwork.

About two percent of people in Europe and in the United States have glaucoma. Glaucoma is a group of eye diseases that can damage the eye's optic nerve and can cause corresponding visual field loss resulting in blindness if left untreated.

A considerable rise in intraocular pressure appears to be a major etiologic factor in glaucoma.

The eyeball is basically a rigid sphere filled with fluids. There are three chambers of fluid in the eye: Anterior Chamber (between the cornea and the iris), Posterior Chamber (between iris, zonule fiber and lens) and the Vitreous Chamber (between the lens and the retina). The first two chambers are filled with a clear fluid called aqueous humour whereas the vitreous chamber is filled with a more viscous fluid, the vitreous humour. The aqueous humour or "aqueous" carries nutrients to the lens and cornea, both of which have no blood supply. The aqueous is constantly secreted by the ciliary body (which is located behind the iris and around the lens) and flows from the posterior chamber through the pupil into the anterior chamber and drains out of the eye through a spongy tissue called trabecular meshwork (TM).

TM is located in the drainage angle of the anterior chamber, between the internal periphery of the cornea and the outer rim of the iris at the location where the iris meets the external wall of the eye (sclera). The fluid drains from the TM into a small canal (the Schlemm canal), then into aqueous collector channels and into aqueous veins.

Aqueous is produced by the ciliary body and removed from the eye at a constant rate to maintain a constant pressure in the anterior chamber of the eye. If the resistance to fluid flow increases, pressure inside the eye increases and the circulation of blood to the optic nerve is restricted. If the ocular pressure remains elevated for prolonged periods of time, the fibres of the optic nerve may cause atrophy resulting in loss of vision in the afflicted eye. Glaucoma is roughly classified into two categories: closed angle glaucoma and open angle glaucoma. The closed angle glaucoma is caused by closure of angle of the anterior chamber by contact between the iris and the inner surface of the TM. Closure of this anatomical angle prevents normal drainage of aqueous from the anterior chamber. In open angle glaucoma the angle of the anterior chamber remains open, but the exit of aqueous through the TM is diminished. The source of resistance to outflow is in the TM.

All current therapies for glaucoma are directed at reducing intraocular pressure. This is initially treated using medical therapy with drops or pills that reduce the production of aqueous or increase the outflow of aqueous. However, these various drug therapies for glaucoma are sometimes associated with considerable side effects, such as headaches, blurred vision, allergic reactions, cardiopulmonary complications and potential interactions with other drugs.

When the drug therapy fails, surgical therapy is used.

Surgical therapy for open angle glaucoma consists of the following methods:

1) LASER:

Trabeculopuncture: Neodymium YAG laser has been investigated as an optically invasive technique for creating a hole through the total thickness of the TM. However, the relatively small hole created by this trabeculopuncture technique is subject to a filling in effect, eventually_. causing treatment failure.

Trabeculoplasty: Argon laser can be used to form scar tissue that contracts and pulls on the TM to improve outflow of aqueous. In many cases this technique fails and very often the treatment needs to be repeated after a period of time.

Goniophotoablation: Excimer laser was used to treat glaucoma by ablating the TM, but success rates did not warrant further human trials. Failure again was due to the filling in of the defects in TM created by repair mechanisms.

2) SURGERY:

Goniotomy/trabeculotomy: These are simple and direct microsurgical dissection techniques with mechanical destruction of the TM. Initially this surgery provided favourable responses, however long term results showed only limited success in adults. These procedures probably failed later following repair mechanisms and "filling" processes. The "filling in" effect is the result of the healing process forming scars, which have the detrimental effect of collapsing and closing the opening that has been created in the TM. Once this opening is closed the pressure builds up inside once more and the surgery fails.

Goniocurettage: This is an ab-interno (performed from the inside) mechanical destructive technique. An instrument similar to a cyclodialysis spatula is used with a microcurette on the tip. Initial results are similar to trabeculotomy with subsequential failure following repair mechanisms and the filling in process.

Trabeculectomy: This is the most commonly performed filtering surgery. It involves creating a tiny filtering valve in the sclera. This procedure controls pressure by creating a new drainage channel through the angle structures to the extracellular space beneath the conjunctiva.

Trabeculectomy is a major surgery and is aided with locally applied anticancer drugs such as 5-flurouracil or mitomycin-c to reduce scarring and increase surgical success. Current mortality associated with trabeculectomy consists of failure (10-15%), infections (a life long risk about 2-5%), choroidal haemorrhage (1%, a severe internal haemorrhage from insufficient pressure resulting in visual loss), cataract formation, and hypotony maculopathy (potentially reversible visual loss from insufficient pressure). Another disadvantage of this procedure is that the body's natural healing process may gradually close the filter, causing the pressure to rise again.

Viscocanulostomy (VC) and Non Penetrating Trabeculectomy (NPT) are two new variations of filtering surgery. These are both major surgery procedures in which the Schlemm canal is surgically exposed by making a large and very deep scleral flap. In the VC procedure, the Schlemm canal is canulated and a viscoelastic substance injected (which dilates the Schlemm canal and aqueous collector channels). In the NPT procedure, the inner wall of the Schlemm canal is stripped away after the canal has been surgically exposed.

Trabeculectomy, VC and NPT are performed under a conjunctival and scleral flap so that the aqueous is drained onto the surface of the eye or into the tissues located near the lateral wall of the eye. Normal physiological outflows are not used.

Drainage devices: When Trabeculectomy, VC and NPT are not considered to have good probabilities of success, a number of implantable drainage devices are used to ensure that the desired filtration and outflow of aqueous through the surgical opening can continue. Placing glaucoma drainage implants also increases the risk of haemorrhage, infection and postoperative double vision that is a complication unique to drainage implants. The treatment procedures and variations described above have numerous disadvantages and are generally only moderately successful. They involve considerable trauma to the eye and require great surgical skill to create a hole in the total thickness of the sclera/cornea in the sub-conjunctival space. Furthermore, normal physiological outflow pathways are not used. Procedure is lengthy and requires an operating theatre and the presence of an anaesthesiologist with all the costs involved, and the vision recovery time is also a long process.

The complications of filtration surgery have induced ophthalmic surgeons to look into alternative approaches for lowering intraocular pressure. The TM and the juxtacanalicular tissues both create the main resistance to aqueous outflow and for this reason they are the logical targets for surgical treatment of open angle glaucoma. Trabecular surgery has a much lower potential risk of choroidal haemorrhage, infections and furthermore, it aims at restoring physiologic outflow mechanisms. This surgery can be performed under local anaesthesia with rapid visual recovery.

The aim of the present invention is to eliminate the disadvantages of the prior art by providing a device for the treatment of open angle glaucoma which is efficacious, easily used by the surgeon, while at the same time, being specifically created for operating in the seat of the diseased area.

These aims have been achieved according to the invention as described in the characteristics listed in the appended independent claim 1.

Other advantageous benefits provided by the invention are described in the subordinate claims.

The Applicant has created a device according to the invention based on a simple logical process: a) In order to maintain the normal anatomy of the eye and to prevent the complications induced by trauma to the tissue, it is essential to restore the natural outflow canals rather than destroy them, open new canals or create a by-pass system. b) The outflow canals do not function because they are blocked by matter deposited in the TM over a period of time. c) The delicate removal of this matter restores the natural outflow without damaging the filtering structure.

In order to remove this matter without provoking any damage or inflammation to the TM, the surgeon must follow the procedure described below:

1) Open a small self-closing opening in the cornea, to penetrate inside the anterior chamber of the eye.

2) Infuse saline solution to maintain an open space.

3) Aspirate, using an appropriate instrument that can be placed close to the TM without provoking any damage. In fact the only way matter blocking the TM can be removed is through aspiration.

While step 1) can be performed using a very small scalpel, commonly used in ophthalmic surgery, steps 2) and 3) are carried out using the device according to the invention which comprises:

- an aspiration cannula created to penetrate inside the anterior chamber of the eye to aspirate the ocular TM, and

- an infusion cannula, associated with said aspiration cannula, to infuse a poly-saline solution into the anterior chamber of the eye, in order to maintain the original open spaces and to compensate the aspiration action on the TM.

Currently there are a variety of two-way devices on the market, both coaxial and non coaxial types, which combine infusion and aspiration actions, and which are specifically dedicated to cataract surgery, but none of these permits access to the delicate structure of the TM for two reasons: the size of the tip which is too large, and the rigidity of said tip which therefore can cause trauma. In fact, the tip of these instruments generally has an external diameter of approximately 1.2 mm and tapers to 0.8 mm only at the very end of the tip for a length of about 2 mm.

There are also cannulae on the market, with a silicone and polyamide tip, used for aspiration only during particular stages of retina and cataract surgery, but none of these are connected to an infusion line.

The special two-way cannula according to the present invention, is composed of an associated system of infusion and aspiration, able to penetrate the eye through a very small temporary and self-closing incision in the cornea, made by a small scalpel, (of the type commonly used in ophthalmic surgery). The said two-way cannula is able to attain the TM situated in the angle of the anterior chamber and remove any matter that blocks the TM, by means of aspiration. At this point, the device according to the invention can be extracted from the eye. An expert surgeon is capable of performing this procedure in less than a minute.

This is made possible by the extremely small size of the tip of the instrument, which also possesses a non-rigid tip that provokes no trauma, in this way eliminating any risk of tissue trauma.

The device according to the invention presents several advantages in comparison with recognised prior art:

1) It is able to restore natural outflow canals.

2) It is able to act on the pathogenic causes of the disease. 3) It helps the surgeon perform easy, rapid surgery using local anaesthesia.

4) It permits the surgeon to work with machines (microscopes and phaco- emulsificators) commonly used by all ophthalmic surgeons.

5) It contributes towards very rapid health and sight recovery.

6) It does not provoke permanent anatomic alterations in the eye or any weakening of the eye itself.

7) It does not damage the filtering structure.

8) It leaves no foreign matter inside the eye.

9) It eliminates all the complications associated with filtering surgery.

10) It eliminates all problems associated with scarring and filling up. 11) It cuts intervention costs considerably.

Further characteristics of the invention will be made clearer from the following detailed description in reference to an embodiment provided simply as an example and to be considered by no means limiting, illustrated in the appended drawings, wherein: FIG. 1 is a cross section illustrating the general anatomy of the eye;

FIG. 2 is a view in perspective, showing an enlarged cross section of the angle between the iris and the cornea;

FIG. 3 is a view in axial cross section, showing the device for treating glaucoma according to the invention; and FIG. 4 is a cross section showing the device shown in Fig 3 inserted in the anterior chamber of the eye to aspirate the TM. FIG. 1 shows certain anatomic details of the eye: cornea 1, conjunctiva 2, extrinsic ocular muscle 3, ciliary body 4, lens 5, iris 6, choroid 7, sclera 8, retina 9, optic nerve 10, macula 11, optic papilla 12, anterior chamber 13, posterior chamber 14, and vitreous chamber 15. FIG. 2 shows in greater detail the trabecular meshwork 16, and the Schlemm canal 17.

The device according to the invention comprises two components: an infusion cannula and an aspiration cannula which can be easily connected to each other in parallel mode, overlaid, or placed in coaxial mode.

As an example, FIG. 3 shows the solution where the two cannulae are associated in a coaxial manner. In this case the device according to the invention comprises an external cannula 18 and an internal cannula 19 positioned co-axially inside the external cannula 18. The external cannula 18 is used for infusion and also acts as a handle, while the internal cannula 19 is used for aspiration.

The infusion cannula 18 extends from a proximal end (destined to be held by the surgeon) and a distal end (destined to penetrate inside the anterior chamber of the patient's eye). Beginning from the proximal end, the infusion cannula 18 presents a first section having a larger diameter, and a second section 21 with a narrower diameter. The second section with the lesser diameter 21 can be either formed in a single part or be separated from the first section.

The first section of the external cannula 18 extends for a length that can vary within a range from a minimum of 20 mm as far as a maximum of 150 mm and even more, and has an external diameter ranging between 5 and 12 mm so that it can be easily held in the surgeon's hand. The first section of the external cannula 18 has an internal diameter that can vary (within a minimum between 1.4 and 0.65 mm) so that it can define an adequate infusion canal. Therefore the thickness of the wall in this first section of the external cannula 18 can vary considerably.

A standard female type connection 20 for syringes is foreseen close to the proximal end of the first section of the internal cannula 18. The axis of the female connection 20 is on a slant at an approximate angle of 45°, in relation to the axis of the first section of the external cannula 18, for easy fluid injection. However the axis of the female connection 20 can also be set at a different angle in relation to the axis of the external cannula 18.

The second section 21 which has a narrower diameter than the external cannula 18 is destined to penetrate inside the anterior chamber 13 of the eye, and therefore it is approximately 2.5 cm long with an external diameter ranging from a maximum of 1.6 mm to a minimum of 0.65 mm, preferably less than 1.2 mm. The second section 21 of the external cannula terminates with an opening similar to a truncated needle.

The aspiration cannula 19 is inserted in an axial manner inside the infusion cannula 18. Sealing means 22, such as O-ring seals, can be placed between the two cannulae 18 and 19, preferably close to the proximal end, so that no air or liquid is able to exit from the proximal end.

The external diameter of the aspiration cannula 19 is narrower than the internal diameter of the infusion cannula, in order to generate a toroidal space between the two cannulae through which a fluid can be infused. The external diameter of the aspiration cannula 19 can vary between 0.20 and 0.70 mm. The proximal end of the internal cannula 19 presents a standard male type conical connection which protrudes from the proximal end of the external cannula 18.

The internal cannula 19 presents a distal portion 24 that protrudes from the distal end of the second section 21 of the external cannula for a distance of about 2-3 mm. The distal end 24 of the aspiration cannula 19 can continue with a segment of tubing 25 made from a pliable material (silicone, teflon, polyamide, etc.) that extends from the internal cannula 19 by about a further 2 - 5 mm. In this manner, the distal end 24 of the aspiration cannula 19 protrudes outside the distal end of the section with the narrower diameter 21 of the external cannula, for a distance of about 4 - 8 mm.

The tube 25 must be as small as possible (with a maximum external diameter equal to or less than 0.65 mm, preferably ranging between 0.12 mm and 0.5 mm, and an internal diameter equal to or less than 0.30 mm).

The segment of tube 25 in pliable material can be welded or glued to the distal end 24 of the aspiration cannula 19, and can also be inserted either on the outside or inside of the distal end. As an example FIG. 3 shows the first possibility where the tube 25 is welded or glued to the distal end 24 of the aspiration cannula 19. However, it is possible to obtain good results by inserting the pliable tube 25 hermetically for a short distance into the terminal section 24 of the aspiration cannula 19, or, on the contrary, by inserting the terminal end 24 of the aspiration cannula hermetically inside the pliable tube 25 for a distance of 1-2 millimetres. In this manner, the distal end of the pliable tube 25 is the only part of the instrument which is in contact with the TM 16.

Furthermore, the whole aspiration cannula 19, or the last distal section of the cannula 19 can be made in a semirigid or flexible material, or at least in a material that causes no trauma, while maintaining the same overall length, the same diameters and the same proportions, but eliminating the need for the pliable tube 25.

Naturally, even though they can vary to a great extent, the diameter of the infusion cannula 18 and the aspiration cannula 19, are connected proportionally so that the infused liquid flow which passes through the space between the two cannulae is equal to or more than the liquid aspirated through the canal of the aspiration cannula 19.

The female 20 and male 23 connections mounted on the device permit easy assembly to both manual infusion-aspiration systems as well as the automatic systems used in ophthalmic surgery.

The flow of the fluids into the device according to the invention are shown in Fig. 3 by the arrows. The fine arrows show the direction of the infusion liquid, and the thick arrows show the direction of the aspirated liquid.

The two cannulae 18 and 19 can be made from materials that can be re-sterilized (steel, silicone, and similar materials), or in non-resterilizable disposable material (plastic and similar materials) or partly in metal and partly in synthetic material.

It should be emphasised that the disposable infusion-aspiration systems currently on the market are mounted with female connections for both infusion and for aspiration, and this can cause connection error, making the use of a double male adaptor necessary. In order to prevent dangerous connection error, the automatic aspiration systems used in ophthalmic surgery have been equipped for several years with non-invertible ends which are designed for male-female connection on the aspiration line and female-male connection on the infusion line. But while the re-sterilizable systems on the market have non-invertible connections, the disposable systems sold by the main manufacturers like Becton Dickinson, Oasis Medical, Eagle Laboratories, etc. are equipped with female connections for both lines.

Further on, in reference to Fig. 4, is the description of the method using the device according to the invention, comprising the following steps:

1) Attach the female connection 20 of the infusion cannula 18 to a drip tube that transfers the sterile polysaline solution.

2) Attach the male connection 23 of the aspiration cannula 19 to a manual or automatic aspiration system.

3) Perform a self-sealing incision in the cornea 1 using a pre-calibrated lancet or scalpel (with a width between 2.2 and 3.2 mm) of the type normally used in ophthalmic cataract surgery.

4) Insert the second section 21 of the infusion cannula 18 with the narrower diameter through the incision in the cornea, inside the anterior chamber 13 of the eye until the pliable tube 25 of the aspiration cannula 19 touches the TM 16 very delicately, as shown in FIG. 4. 5) Aspirate the TM 16 through the aspiration cannula 19 covering a curved area between 60° and 180°, and at the same time infuse a sterile poly-saline solution into the anterior chamber 13 of the eye, in order to maintain the same original open space and to compensate the aspiration action on the TM 16. 6) Remove the instrument from the patient's eye.

Numerous variations and changes can be applied to details of the embodiment of the invention, by those skilled in the art, while remaining within the scope of the invention as described in the appended claims.

Claims

1. Device for the treatment of glaucoma comprising:

- an aspiration cannula (19) adapted to penetrate the anterior chamber (13) of the eye to aspirate the trabecular meshwork (16) and

- an infusion cannula (18), associated with said aspiration cannula (19), to infuse a sterile poly-saline solution in the anterior chamber (13) of the eye, in order to maintain the original open spaces and to compensate the aspiration action on the trabecular meshwork (16).

2. Device according to claim 1, characterised in that said infusion cannula (18) has a distal part (21) having a narrow diameter in order to penetrate the anterior chamber (13) of the eye and a proximal part having a larger diameter designed to be held in the user's hand.

3. Device according to claim 1 or 2, characterised in that said aspiration cannula (19) is positioned in a coaxial manner inside said infusion cannula (18), and presents a distal end (24) that protrudes from the distal part (21) of the infusion cannula (18).

4. Device according to any one of the previous claims, characterised in that the distal end (24) of said aspiration cannula (19) or the total aspiration cannula is made from a non-rigid material that will not provoke trauma to tissue.

5. Device according to any one of the previous claims from 1 to 3, characterised in that the distal end (24) of said aspiration cannula (19) is provided with a small tube (25) made of a pliable material which protrudes beyond the distal end of the infusion cannula (18) to make contact with the ocular trabecular meshwork (16).

6. Device according to claim 5, characterised in that said small tube (25) at the distal end of the aspiration cannula is made from a pliable material such as silicone, teflon, polyamide or similar material.

7. Device according to claim 5 or 6, characterised in that said small pliable tube (25) at the distal end of the aspiration cannula has an external diameter equal to or smaller than 0.65 mm, preferably ranging between 0.12 and 0.5 mm and an internal diameter equal to or less than 0.3 mm.

8. Device according to any one of the previous claims characterised in that said infusion cannula (18) presents a standard type female connection (20) on its proximal part, for attachment to syringes or automatic drip tubes .

9. Device according to any one of the previous claims, characterised in that said aspiration cannula (19) presents a conical male connection (23) on its proximal end, for attachment to automatic or manual aspiration systems.

10. Device according to any one of the previous claims, characterised in that said aspiration cannula (19) and/or said infusion cannula (18) are made in re-sterilizable material such as steel or silicon.

11. Device according to any one of the previous claims from 1 to 9, characterised in that said aspiration cannula (19) and/or said infusion cannula (18) are made from disposable materials such as plastic or synthetic materials.