System for surgically correcting presbyopia

Device and method for corrective surgery for presbyopia

Full description

Background of the invention

This invention relates to a device and method for surgically correcting presbyopia. The system used according to the invention (named PRESBYSYSTEM) includes several different elements which, when used in combination, modify the front corneal curvature, thereby creating a multifocal surface that allows the patient to see normal vision with respect to objects at a distance, while allowing At the same time, the patient can see nearby objects normally. This simultaneous correction of near and far vision is done using only part of the comeal surface of the cornea (the middle part). This means that the part of the cornea used for near vision is not the same part that is used for distance vision. As they grow older, most people suffer from presbyopia. The natural method used to correct this issue is by using bifocal lenses. But some individuals do not prefer wearing glasses, especially bifocal glasses, for many reasons. Bifocal lenses have lines where the parts of the two lenses meet. In addition, people have to get used to reading through a relatively small part of the lens while looking at distant objects through another part of the lens. Bifocal lenses also have the same disadvantages as regular lenses. These disadvantages include that the lenses are breakable and fogged when moving from a cold place to a warm place, and that they become covered with steam in hot places, and they require periodic cleaning.

The invention relates to a device and method for correcting presbyopia problems directly on the patient's eye so that the use of lenses is avoided and so that the patient's eye is automatically prepared to highlight the focus

Seeing up close and far.

General description of the invention

The invention relates to a process for surgical correction of presbyopia. The procedure involves anesthetizing the patient and marking the part of the eye that will be removed. At least part of the cornea is cut to expose the underlying corneal connective tissue. An annular portion of the underlying connective tissue of the cornea is then removed using radiation from a laser beam. After excision it is repositioned

The cornea on the eye.

In the operation according to the invention, the cornea can be cut so that part of it remains intact, and the cornea can then be bent to expose the underlying connective tissue of the cornea. Alternatively, the cornea can be sectioned so that an entire disk of the cornea is removed, thus exposing the underlying connective tissue of the cornea. The corneal disc can then be placed back on the eye.

The underlying corneal connective tissue must be dried after being cut and before the ablation procedure, otherwise an uneven excision may result due to the presence of fluids on the underlying corneal connective tissue.

During the ablation, the laser beam can be directed circularly until an annular ablation with a predetermined width and depth is obtained. Alternatively, a mask can be placed over the central area of the underlying connective tissue of the cornea to prevent radiation from reaching

Laser beam to the central part. In this case the mask diameter is controlled (and somewhat larger than the mask diameter) so that an annular resection of predetermined width and depth is obtained. The mask can be made of polymethyl methacrylate or another suitable synthetic resin. The laser can be a conventional pulsed laser. Conventional pulsed laser: After excision, the excised part must be washed to prevent edema. This can be done by washing with a brush and irrigating the excised part. When the corneal fragment is put back in place correctly, it can be reattached to the eye by blowing air onto the cornea.

The invention also relates to a system for surgically correcting presbyopia. The system includes a means for marking the portion of the patient's eye to be resected. It also includes a means of cutting at least part of the cornea of the patient's eye for the purpose of exposing the underlying connective tissue of the cornea. The system also includes a means to remove an annular portion of the underlying connective tissue of the cornea. This ablation method includes a laser device (such as a pulsed laser), where the ablation is performed by shining an irradiating beam on the underlying connective tissue of the cornea from the laser device. It is possible to provide a corneal shaping tool as a means of cutting, as the corneal shaping tool either partially cuts the cornea so that part of the cornea remains as it is without removing it, or it removes a disk from the cornea completely, as mentioned above. The system may further include a means of drying the underlying corneal connective tissue after exposing it by cutting, for example by exposing it to an air current.

In order to remove the underlying connective tissue of the cornea in an annular fashion, a mask can be provided with the ablation method to place it on a central area of the underlying connective tissue of the cornea to block the radiation from the laser device. This mask can be made of a laser-blocking material such as polymethyl methacrylate (PMMA) or another suitable synthetic resin. This embodiment is provided with a means of delivering a laser beam of a predetermined diameter from the laser beam emanating from the laser in order to determine the beam width in order to obtain an annular ablation of a predetermined width and depth.

According to the invention, it is preferable for the system to be equipped with a means of cleaning the underlying connective tissue portion of the cornea from which it is removed. This cleaning method may include a fine brush or a means of irrigating the removed part, or both.

Brief explanation of the drawings

The invention will be described in greater detail with the help of the attached drawings where:

Figure (1): A schematic view of part of an Excimer laser where the beam axis is tuned.

Figure (2): A schematic view of the laser beam path and the optical devices used in an embodiment of the device according to the invention.

Figure (3a): The laser beam is shown performing the ablation procedure on the cornea while the mask protects the central area of the cornea.

Figure (3b): shows a ring of the resection area.

Figure (3c): The final appearance of the keratectomy is shown.

Detailed description

The system according to the invention includes an Excimer laser, an automatic corneal shaper, a pneumatic fixation ring, a mask, and an air source. A preferred automated corneal shaping tool for use in the system according to this invention is the automated corneal shaping tool described in U.S. Patent No. 5,133,726 by the same inventor of this application, issued on July 27, 1992. This entire patent is incorporated herein by reference. Using only local anesthesia, the eye is fixed with a retaining ring, which also serves as a guide for the automated corneal shaping instrument. A retaining ring as described in the above US patent allows complete control of eye movement. The pupil of the eye will be the reference point for performing a completely central excision of the underlying corneal connective tissue. When the eye is fixed, a partial keratectomy is performed using an automated corneal shaping tool. The cornea may be partially removed, which means using the cornea flap technique. This means that a peripheral part of the corneal disc remains attached to the base of the cornea, which allows it to be returned to its position more easily and accurately when the ablation is completed. When the flap is retracted, the underlying connective tissue of the cornea, the comeal stroma, is exposed, which is an ideal tissue for performing the ablation on. The superficial layers of the cornea remain without any changes occurring on them. In this way, the undesirable healing is avoided, and inaccuracy in the post operative correction and regression is also avoided.

Using an Excimer laser, which allows ablation with a precision of 0.24 micrometers/pulse, annular ablation is performed on the underlying connective tissue of the cornea with a diameter not exceeding 3.5 millimeters with a central area ranging between 2 and 3 millimeters. Annular ablation produces a central protrusion of the underlying connective tissue of the cornea, such that when the flap is repositioned in its original position, the change in curvature of the underlying connective tissue is transmitted to the anterior surface of the cornea, thus turning into a multifocal surface myopic in its central part. This enables the patient to read without optic correction lenses after this surgery, regardless of the patient’s age or loss of accommodation. Cycloplasty can be done separately to correct presbyopia, or it can be done with surgeries for hyperopia, myopia, or astigmatism, either separately or in combination. After resection, the process continues with a very careful cleaning of the interface using a balanced saline solution, a brush, and aspiration to ensure that the interface is free of impurities, epithelial cells, and foreign particles. The chip is then returned to its previous position, properly oriented to avoid changing its normal position. The edges of the flap are dried using air for several seconds to obtain adhesion of the flap so that the patient can leave the operating room without bandages and to achieve a recovery time of less than 24 hours. The following is a more detailed description of an example of the device and method for performing presbyopia correction surgery. A conventional local anesthetic (i.e. in the form of eye drops) is administered to the eye

the patient. This local anesthetic is sufficient for the surgical method according to the invention to perform the surgery without pain. The pneumatic retainer ring is then placed over the eye. In this type of surgery, positioning the instrument on the pupil in a centering manner is very important. In addition, it is desirable to have the pupil as small as possible. For this reason, it is useful to apply a drop of 2% Isopto-Caprine half an hour before surgery. From this time on you will use this small pupil as a reference point for making the ablation.

Surgery according to the invention must be performed in a sterile area (ie an operating room) because the cornea will be touched not superficially as in photo-ablation for the correction of myopia. However, in the method of presbyopia correction surgery according to the invention, a corneal flap is lifted in the form of a thin laminar flap in order to work directly on the underlying connective tissue of the cornea. This is why surgical fields exist to isolate the working area, and a blepharostat eyelid retractor (eye opener) is provided to keep the eye open enough so that surgery can be performed.

As a feature a marking and positioning tool is used in implementing the invention. The marking and positioning tool used in this new method has a bnllock eye shape with two concentric circles in the center (thereby forming an inner ring and an outer ring) so that the outer part has a diameter of about 10.5 millimeters and the

The inner diameter is from about 3 to about 5 millimeters.

This marking and locating device shall be impregnated with a coloring product such as gentian violet, methylene blue, or the like. The marker and positioner is placed on the patient's eye. The inner ring has the function of keeping the marker and positioner in a central position with the reference point being the pupil. The outer ring is thus determined automatically and will therefore be used as a reference for positioning the pneumatic mounting ring. In addition to these two rings, the Markers and Places tool has a diagonal para-radial line connecting these two rings. Diagonal alignment lines are useful in guiding the corneal flap with sufficient accuracy. Alternatively, if a disc is completely removed from the cornea in surgery instead of using a flap in the cornea, alignment lines are used to help place the disc in the correct place, i.e. the epithelial towards the outside and the underlying connective tissue of the cornea towards the inside. When present in this form, it It can be directed appropriately.

The pneumatic grommet has two main components. The ring itself is attached to the eye via a bottom vacuum chamber, which allows it to hold the eye in place and raise interocular pressure. This facilitates the necessary cuts in the cornea on a regular basis. The fixation ring also has a central orifice from which the cornea protrudes. At its upper part is the most important component of the fixation ring, which is a line of toothed protrusions that contact the pinions of the mechanical corneal shaping device (see US Patent No. 5,133,726). This allows the corneal shaper to be positioned horizontally to perform a thin laminar cut of the retina. The second component of this ring is a handle

The vacuum chamber is connected to the vacuum pump mounting ring. The air pump is responsible for suction fitting the ring on the patient's eye. The handle is also used to move the eye when the ring is attached to the eye.

The next step of the surgical procedure is done with an automated corneal shaping instrument as discussed above. The shaping tool is placed over the fixing ring, and when the shaping tool's gears touch the serrated protrusions of the ring, the shaping tool's motor starts to work and the shaping tool moves horizontally and uniformly over the retina. The cutting tool of the forming tool will make thin laminar cuts very precisely relative to the thickness in the manner described in U.S. Pat. No. 5,133,726.

It is preferable to stop the motor of the shaping tool in a pre-determined cutting position so that a small portion of the cornea is still attached to one side. When this thin section is lifted, the underlying connective tissue of the cornea will be exposed. The underlying connective tissue of the corneal stroma is where the surgery will be performed. Because it has a great advantage, which is that once the corneal flap is repositioned after removing the basic connective tissue of the cornea, all the natural structures of the eye will be preserved in their original place, but with a change in the surface features (topography). Thus, the need for unwanted healings and other changes that may be avoided. Occurs when this system is not being used.

When examining the surface of the underlying connective tissue of the cornea, it must be dried before ablation with the Excimer laser device is performed because any fluid remaining on the underlying connective tissue of the cornea will be considered

By laser device it is corneal tissue. This will lead to irregular ablation, meaning that different depths of ablation will be produced on the underlying connective tissue of the cornea. One of the key components of this new system for correcting presbyopia is the Excimer laser. The Excimer laser system, as shown in Figures (1) and (2), will be used to correct this visual defect by allowing the ablation of the underlying connective tissue of the retina in the required manner, location and depth to create a multifocal surface. The multifocal surface of the cornea allows for good farsightedness as well as good nearsightedness. This vision is usually lost during aging as a result of loss of physical accommodation and loss of elasticity of the lens.

The system includes a novel combination of the above elements to achieve a ring-shaped ablation within the area of the cornea that is not used in farsightedness. These are the theoretical and real foundations of the system according to the invention for correcting presbyopia. There may be different ways to obtain results as will be described below.

In one embodiment the laser device is directed toward the area where the ablation is to be performed. The laser device directs the laser beam in a circular motion so that the ablation is done to the required width and depth to obtain the desired curvature. For this purpose, the device that sends the laser beam includes an eye follower system to follow any eye movement so as not to produce an irregular annular ablation.

In another embodiment as shown in Figure 3a, the light of the laser beam is sent toward the center of the selected area using the small pupil of the eye as a reference point. A mask is placed on the central space

To prevent the laser beam from touching the underlying connective tissue of the cornea in the central area. In this way, the ablation will be delimited outside by the chosen diameter of the laser beam and inside by the borders of the mask, thus obtaining an annular area as shown in Figures (3b) and (3c). By using the mask, the cornea above the pupil area will not be affected at all.

Taking the above into account, the surgical method for correcting presbyopia proceeds as follows: When the underlying connective tissue becomes completely dry, the area that will not be touched by the laser beam is determined. This area will be called the optic zone, taking into account that the main factor in the success of the operation lies in precisely determining the center of this visual zone. The diameter of this visual area should be between 2 and 3 millimeters.

Now a mask made of a material that stops laser rays is placed on the selected area. For the mask, a material called polymethyl methacrylate (PMMA) is usually used, and it must have the same dimensions as the specified marks.

Then the laser device is placed to deliver laser beams to the cornea. These laser systems are commercially available as those supplied by Chiron Thechnolas GmbH. The laser device has been pre-configured to produce a laser beam of the desired diameter. It can also be pre-adjusted to provide the number of pulses required to obtain an ablation of the appropriate depth to obtain the necessary change in corneal curvature to obtain the multifocal effect. During the period of operation of the laser equipment on the cornea, and mainly when the laser equipment is not equipped with an eye-tracking system, it is convenient to fixate the eye with a pneumatic fixation ring because this allows regular excision of the ablated ring.

When the excision step is completed, the mask is removed and the treated area is examined and cleaned completely, making sure that there are no epithelial cells or foreign particles on the surface. The cleaning step is usually done using a very fine brush with continuous irrigation with a neutral saline solution that has an osmolarity similar to that of the cornea. This avoids the occurrence of large edema, which will require a longer recovery time for the patient.

Now the treated surface is ready to receive the flap, which must be put back in its position with absolutely correct orientation and without folds, which will result in comeal astigmatism and reduced visual acuity. When the corneal flap is returned to its position, the tissue is dried using filtered air directed primarily at the edges of the flap to ensure good adhesion of the flap to the treated surface. This adhesion can be confirmed or checked using small tweezers.

When tissue adheres, the blepharostat eyelid retractor and surgical fields are removed and the patient is asked to blink several times and close his eyes forcefully to further indicate tissue adherence. If no complications are observed, the operation is now completed successfully. While the invention is described using several embodiments and preferred methods of performing surgery, those with experience in this scientific field will recognize that numerous changes and modifications can be made without departing from the spirit and scope of the invention as specified in the appended claims.