RU2840446C1 - Method for preparing graft for performing posterior layered keratoplasty - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to ophthalmosurgery, and can be used for preparing a donor graft for posterior layered keratoplasty. During formation of the donor graft, at the initial stage of its separation, the disk is separated from the underlying corneal stroma in the lower segment at 2-3 mm from the edge of the disk. After that, using the corneal scissors in the separated segment, making the marginal guide mark in the form of notches from the outer surface of the disc at angle of 40-60° to the tangent to the transplant circle with a length of not more than 1 mm to the right or left side. That is followed by completing the corneal disk separation over the whole area and moving it into the glide funnel with the endothelium upwards for further transplantation in the recipient’s eye.

EFFECT: invention provides an increase in the effectiveness of the intervention by ensuring the control of the correct orientation of the donor graft, excluding its inverse positioning, creation of optimum conditions for transparent engraftment of a graft due to preservation of endothelial cells, and also obtaining the maximum possible visual functions of the recipient.

1 cl, 2 dwg, 2 ex

Description

The invention relates to medicine, namely to ophthalmic surgery, and can be used in the process of surgical treatment of primary and secondary endothelial dystrophy of the cornea.

Corneal endothelial dystrophy is one of the common eye pathologies associated with a decrease in the density and functional activity of the cells of the posterior epithelium (endothelium) of the cornea and leading to the development of corneal edema, epithelial bullosity, persistent vision loss and the appearance of corneal syndrome in patients, which significantly reduces the quality of life of this group of patients.

A widely used and effective treatment option for primary and secondary endothelial corneal dystrophies is currently recognized as posterior lamellar keratoplasty (PLK), also known as DSEK (Descemets Stripping Endotelial Keratoplasty), which can be performed, in particular, using a femtosecond laser (FSL). The technique involves intraoperative fixation of the graft to the recipient's cornea using sterile air introduced into the recipient's anterior chamber (Busin M., Bhatt P. R., Scorcia V. A. Modified technique for Descemet membrane stripping automated endothelial keratoplasty to minimize endothelial cell loss // Arch. Ophtalmol. - 2008. - Vol. 126. - P. 1133-1137).

The implementation of the ZPK using FSL consists of a femtosecond stage of donor cornea preparation, during which a donor corneal disc of the required diameter and thickness is formed, isolated with a femto spatula, the disc is loaded into a device for introduction into the anterior chamber of the recipient (for example, into a Busin glide) with the endothelium facing up and placed in a sterile bottle with a preservation medium, and a surgical stage, during which, after performing descemetorhexis and removing the excised Descemet membrane (DM) of the recipient, the endothelial-corneal disc is introduced with the help of the device used into the anterior chamber through a corneal tunnel incision, straightened, after which it is centered and fixed on sterile air introduced into the anterior chamber. (Mark S. Gorovoy, MD Descemet-Stripping Automated Endothelial Keratoplasty, Cornea, Vol. 25, Num. 8, September 2006).

When performing the surgical stage of the ZPK, it is critically important to correctly orient the donor transplant in the anterior chamber and fix it with the endothelial layer downwards to ensure adequate physiological processes of transplant engraftment and further effective functioning of the recipient's visual analyzer.

However, there are rare cases of unexpected intraoperative situations, in which the transplant may chaotically fold and turn over from its original position during insertion. Most often, such moments occur during the process of straightening the donor transplant by supplying BSS, and during the introduction of sterile air for centering and fixation of the transplant.

In these cases, in the absence of any reference marks on the transplant after its straightening, one cannot be sure of the correct orientation of the transplant with the endothelium down, and the surgeon is forced to fix the endothelial-corneal disc at random, which can lead to an inverted orientation of the transplant, and, accordingly, to the ineffectiveness of the intervention, and is extremely undesirable given the existing shortage of donor material.

It is known to apply a marginal orienting notch in the form of a non-isosceles triangle when cutting out a donor DM transplant for its transplantation (patent RU No. 2600158), the presence of which allows for monitoring the correct orientation of the DM in the anterior chamber and reducing the risk of inverse positioning of the DM. We have adopted this method as a prototype.

However, when cutting out a triangular notch, the total number of endothelial cells decreases due to the removal of part of the tissue.

The proposed invention solves the problem of developing a new method for preparing a transplant for performing ZPK, devoid of the indicated drawback.

The essence of the method is as follows.

During the femtosecond stage of forming a donor transplant of the required diameter, at the stage of its isolation, the disc is separated with a femtospatula from the underlying corneal stroma in the lower segment at a distance of 2-3 mm from the edge of the disc, after which, with corneal scissors, a marginal orienting mark is made in the separated segment in the form of a notch from the outer surface of the disc at an angle of 40-60 degrees to the tangent of the circumference of the transplant no more than 1 mm long to the right or left side (see Fig. 1).

The technical result of implementing the invention consists in increasing the effectiveness of the intervention by ensuring control of the correct orientation of the donor transplant, eliminating its inverse positioning, increasing the convenience of the surgeon when working with the transplant in the anterior chamber and creating optimal conditions for transparent engraftment of the transplant and obtaining the maximum possible visual functions of the recipient.

When forming an orienting mark in the form of a notch, the total number of endothelial cells is preserved, which helps to obtain the maximum possible visual functions of the recipient. At the same time, the flap obtained after the notch is made does not have excessive mobility due to the presence of a stromal layer, does not require additional manipulations to straighten it, and does not interfere with further surgical manipulations with the transplant to straighten it, center it, and fix it in the recipient's eye.

An angle of 40-60 degrees to the tangent circumference of the transplant for making a marginal orienting mark and its length of no more than 1 mm are optimal and sufficient to provide information for the surgeon when positioning the transplant, and safety for further manipulations with the transplant.

The method is carried out as follows.

The donor corneal transplant is first formed using a femtosecond laser. The native corneoscleral disc of the donor is fixed in the IPC with the endothelial side up. Using a continuous supply of BSS solution, the IPC is filled until the optimal pressure is achieved to maintain the volume of the IPC, smooth out corneal folds and create optimal pressure on the donor cornea during applanation. Next, a viscoelastic solution (methylcellulose) is applied to the endothelium of the donor cornea. After applying the viscoelastic to the surface of the endothelial layer, a time of 30-60 seconds is maintained, which is necessary for its uniform distribution in the form of a layer over the entire surface of the endothelium. A treatment pack for the donor cornea is fixed on the head of the femtolaser. The treatment pack and the donor cornea are docked to the required applanation area. The contact of the cornea and the treatment pack is controlled using intraoperative optical coherence tomography (OCT). According to OCT data, during applanation using a viscoprotector, a smooth continuous interface profile is noted, and the absence of endothelial folds and corneal stroma is determined. Then, a donor corneal disc of the required diameter (6.5 - 8.5 mm) is formed with a femtosecond laser to a depth of no more than 145 μm. After removing the laser head from the surface of the donor cornea, the formed donor corneal disc is isolated with a femtospatula. First, the disc is separated from the underlying corneal stroma in the lower segment at a distance of 2-3 mm from the edge of the disc with a femtospatula. Corneal scissors are used to make a marginal orienting mark in the form of a notch from the outer surface of the disc at an angle of 40-60 degrees to the tangent of the circumference of the transplant no more than 1 mm long to the right or left side, and the surgeon remembers in which direction the notch was made. The direction of the incision depends on the surgeon's convenience in each specific case.

Then, using a femto spatula, the corneal disc is separated over the entire area and moved into the glide funnel (Busin type), with the endothelium facing upward. A strip of viscoelastic preparation is applied to the surface of the endothelium, which serves to protect the endothelial layer of the cornea when the transplant is introduced into the anterior chamber of the eye.

At the surgical stage, after the recipient's surgical field has been treated and anesthesia has been administered, two paracenteses are formed and viscoelastic is introduced into the anterior chamber. A descemetorhexis with a diameter of 8-9 mm is performed, the excised DM is removed from the anterior chamber and the viscoelastic is washed out. A 23 G irrigation port is installed in the anterior chamber and a main tunnel incision of 5.0 mm in length is formed. The tip of the Bead glide is inserted into the main tunnel incision, and with tweezers inserted through the corneal paracentesis opposite to the main incision, the donor transplant is moved from the glide into the anterior chamber under conditions of constant maintenance of its volume by the irrigation flow of BSS solution through the irrigation port. If the transplant does not spontaneously straighten in the correct position with the endothelium down, it is straightened by supplying the irrigation flow through the cannula. The correct position of the graft in the anterior chamber is controlled by the orientation mark. The surgeon controls that the mark is located in the opposite direction from the initial formation, which will be a marker of the correct orientation of the graft. Since after the introduction of the donor graft into the anterior chamber the orientation of the endothelial layer changes (with the endothelium upwards at the femtostage, with the endothelium downwards in the anterior chamber of the recipient), the direction of the orientation mark should change to the opposite when the graft is correctly positioned in the anterior chamber.

Then sterile air is introduced under the graft, which centers the graft and fixes it to the recipient's cornea with the endothelium facing down. At these stages of the operation, the orienting mark also allows the surgeon to confidently control the correct position of the graft. After fixing the graft in the correct position with air, the main incision and paracentesis are sutured with a 10-0 nylon suture.

The invention is illustrated by the following clinical examples.

Example 1. Patient Ch., 73 years old, was an inpatient at the Tambov branch of the Federal State Autonomous Institution "National Medical Research Center "MNTK "Microsurgery of the Eye" named after academician S.N. Fedorov" from 18.09.23 with the main diagnosis of OS: bullous keratopathy. Concomitant diagnosis of OS: primary Fuchs' corneal dystrophy, operated retinal detachment, age-related macular degeneration, cicatricial-atrophic form, descending partial atrophy of the optic nerve, pseudophakia.

Vis OS=0.01 n/c

Pachymetry in the center of the cornea is 741 µm.

Corneal OCT: subepithelial bullae, corneal edema, DM folds. On September 18, 2023, a ZPK operation was performed on OS with femtosecond preparation of a 145-μm-thick donor graft using the proposed invention. At the stage of graft isolation with corneal scissors, an edge orienting mark was made in the form of a notch from the outer surface of the disc at an angle of 40 degrees to the tangent circumference of the graft with a length of 0.8 mm to the right. No complications were observed during the operation or in the postoperative period.

The patient was discharged from the hospital on the seventh day after the operation after complete epithelialization of the cornea according to biomicroscopy data.

Upon discharge:

Vis OS=0.04 n/c

At examination 1 month after surgery:

Vis OS=0.05 n/c

Pachymetry in the center of the cornea is 505 µm.

Corneal OCT: transplant thickness in the center is 68 µm, at the periphery 76 µm. Corneal edema and epithelial bullae are absent (see Fig. 2). The marginal notch (1) is oriented to the left, indicating correct transplant orientation.

At examination 3 months after surgery:

Vis OS=0.05 n/c

Pachymetry in the center of the cornea is 505 µm.

OCT of the cornea: the thickness of the transplant in the center is 68 µm, at the periphery 76 µm.

Example 2. Patient G., 74 years old, was an inpatient at the Tambov branch of the Federal State Autonomous Institution "National Medical Research Center "MNTK "Eye Microsurgery" named after academician S.N. Fedorov" from 02.11.23 with the main diagnosis OD: bullous keratopathy. Concomitant diagnosis OD: primary Fuchs corneal dystrophy, high myopia, macular and posterior pole degeneration, pseudophakia.

Vis OD=0.01 n/c

Pachymetry in the center of the cornea is 645 µm.

OCT of the cornea: subepithelial bullae, thickened cornea

On November 3, 2023, a ZPK operation was performed on the OD with femtosecond preparation of a 145-μm-thick donor graft using the proposed invention. At the stage of graft isolation with corneal scissors, an edge orienting mark was made in the form of a notch from the outer surface of the Disc at an angle of 60 degrees to the tangent circumference of the graft 1.0 mm long. No complications were observed during the operation or in the postoperative period. The patient was discharged from the hospital on the seventh day after the operation after complete corneal epithelialization according to biomicroscopy data.

Upon discharge:

Vis OD=0.1 n/c

At examination 1 month after surgery:

Vis OD=0.2 n/c

Pachymetry in the center of the cornea is 555 µm.

Corneal OCT: transplant thickness in the center is 46 µm, at the periphery 82 µm. Epithelial bullae are absent.

At examination 3 months after surgery:

Vis OD=0.2 n/c

Pachymetry in the center of the cornea is 573 µm.

OCT of the cornea: the thickness of the transplant in the center is 54 µm, at the periphery 92 µm.

Using the proposed method, 4 surgeries of the ZPK were performed in the Tambov branch of the Federal State Autonomous Institution "National Medical Research Center "MNTK "Microsurgery of the Eye" named after academician S.N. Fedorov". In all cases, the correct orientation of the transplant was achieved, and it was possible to achieve an improvement in visual functions.

Claims (1)

A method for preparing a donor transplant for performing posterior lamellar keratoplasty, including forming a donor corneal disc of the required diameter, isolating it and moving the isolated disc into the glide funnel with the endothelium facing upward for subsequent transplantation in the recipient's eye, characterized in that when forming a donor transplant, at the beginning of the stage of its isolation, the disc is separated from the underlying corneal stroma in the lower segment at a distance of 2-3 mm from the edge of the disc, after which, with corneal scissors, an edge orienting mark is made in the separated segment in the form of a notch from the outer surface of the disc at an angle of 40-60° to the tangent circumference of the transplant no more than 1 mm long to the right or left side, after which the corneal disc is isolated over the entire area and moved into the glide funnel.