RU2814745C1 - Lens fragmentation method using femtosecond laser - Google Patents

Abstract

FIELD: medicine; ophthalmology.

SUBSTANCE: lens is fragmented with the help of a femtosecond laser, the lens is incised and its center is ground. Laser energy is used to incise the lens as in Fig. 1 along four mutually perpendicular lines, which form nine fragments, of which the central fragment of square shape with length of sides in range of 1.0–3.0 mm is crushed by additional cuts, and four rectangular fragments and four triangular fragments are located around the central fragment. Depth and diameter of the incision line area depend on the thickness of the lens and the width of the pupil.

EFFECT: method enables atraumatic destruction of the lens with its subsequent removal within the capsular bag, reducing the load on the lens capsule, its ligamentous apparatus, the iris and the cornea during the operation, absence of intraoperative and postoperative complications associated with the stage of lens removal.

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Description

The invention relates to the field of medicine, namely to ophthalmology and is intended for lens surgery using a femtosecond laser for cataracts or refractive replacement of a transparent lens with an artificial one.

Femtolaser support for lens surgery has become increasingly widespread in recent years. Modern ophthalmic femtosecond lasers are used to perform a pre-division of the lens before ultrasonic emulsification using a phacoemulsifier and provide wide variability in the patterns of fragmentation of the lens nucleus. The pattern is a scheme for applying cuts to the lens with laser pulses within its volume. The main advantage of performing femtolaser lens fragmentation over the manual technique is the reduction in the volume of manipulation to separate the lens into fragments and a significant minimization of the use of ultrasound energy, which leads to a reduced risk of intraoperative complications and a faster recovery of visual functions (Abell RG, Kerr NM, Vote BJ (2013) Toward zero effective phacoemulsification time using femtosecond laser pretreatment. Ophthalmology 120:942–948. https://doi.org/10.1016/j.ophtha.2012.11.045).

The densest part of the lens is its nucleus, so it is advisable to use a pattern where the central part of the lens is subject to the greatest femtolaser fragmentation.

There is a known method for femtolaser fragmentation of the lens, where the lens nucleus is divided into small fragments, which represent many adjacent elongated segments in the lens, which individually taper from the anterior end region to the posterior end region (US application No. 20140135749, https://patents.google.com/ patent/US20140135749A1/en). Using a phacoemulsifier needle, the laser-cut center of the lens is first removed, then the remaining less dense peripheral part is removed.

The disadvantage of this method is the excessive grinding of the lens nucleus with a laser, which leads to the subsequent removal of its dense part, and the less dense part remaining on the periphery in the form of a “bowl” does not allow for its safe fixation on the phacoemulsifier needle with a vacuum, which can lead to uncontrolled displacement (“ failure") of the needle towards the capsule and provoke a complication in the form of its rupture.

The closest, adopted as a prototype, is the method of fragmentation of the nucleus with a femtosecond laser, namely the “cylinder” pattern (S.N. Sakhnov, A.G. Zabolotniy, E.S. Onishko. Comparative analysis of various patterns (models) of femtosecond laser fragmentation of the lens nucleus in uncomplicated senile surgery cataracts // Modern problems of science and education. – 2019. – No. 3.;

URL: https://science-education.ru/ru/article/view?id=28767), where the division of the nucleus is carried out with grinding in the center and the formation of radial cuts around. During subsequent phacoemulsification, the central part that is most crushed by the laser is first removed, then the peripheral trapezoidal fragments are brought into the freed central zone with a phaco needle and removed one by one.

With all the advantages of the known method, adopted as a prototype, disadvantages should be noted. After removing the more crushed nucleus of the lens in the center, the peripheral trapezoidal fragment is fixed on the phaco needle with a vacuum; when trying to remove it into the vacated central zone, the withdrawn fragment becomes jammed between neighboring ones. To wedge, the fixed fragment must be significantly shifted upward, and nearby fragments must be moved apart using an additional tool. At the same time, excessive manipulations place an increased load on the lens capsule, its ligamentous apparatus, iris and cornea, which can provoke intraoperative and postoperative complications.

The objective of the invention is to create an effective and safe method for fragmenting the lens using a femtosecond laser.

The technical result to which the invention is aimed is the atraumatic destruction of the lens with its subsequent removal within the capsular bag, reduction of the load on the lens capsule, its ligamentous apparatus, iris and cornea during surgery, the absence of intraoperative and postoperative complications associated with the stage of lens removal .

The specified technical result in the method of fragmenting the lens using a femtosecond laser is achieved by using laser energy to make incisions in the lens along four mutually perpendicular lines, which form nine fragments, of which the central fragment is square in shape with side lengths ranging from 1.0 to 3.0 mm are crushed by additional cuts, and four rectangular-shaped fragments and four triangular-shaped fragments are located around the central fragment, while the depth and diameter of the cut line area depend on the thickness of the lens and the width of the pupil.

The novelty of the proposed method lies in the fact that femtolaser fragmentation of the peripheral part of the lens nucleus is carried out not by radial, but by parallel incisions, which, after removing the more crushed central part of the lens, makes it possible to fix a peripheral rectangular fragment on a phaco needle with a vacuum and unhindered, without mechanical load on the surrounding structures , push it into the vacated central zone for further emulsification. The remaining rectangular fragments are removed in a similar way.

Using the proposed method, 30 operations were performed, 3 of them for refractive purposes. In all cases, no intraoperative or postoperative complications were identified. In lens surgery for refractive purposes, lens fragments were removed using vacuum aspiration; the use of ultrasound was not required. The load on the lens capsule, its ligamentous apparatus, iris and cornea is reduced. Intraoperative and postoperative complications associated with the stage of lens removal were excluded.

In FIG. Figure 1 shows a diagram of lens fragmentation, where 1 is a central square-shaped fragment, 2 is rectangular fragments, 3 is triangular fragments. In FIG. Figure 2 shows a photograph of the eye immediately after femtolaser exposure. In FIG. Figure 3 shows a photograph of an eye where the central fragment of the square-shaped lens has already been removed, and the peripheral rectangular fragment is pulled out like a “desk drawer” into the vacated central zone for further emulsification.

In practice, the method is carried out as follows. The preparation stage is carried out as standard. Before starting the laser treatment procedure, the proposed lens fragmentation pattern is selected on the screen of the FEMTO LDV Z8 femtolaser device (Ziemer Ophthalmic Systems AG, Switzerland), the laser energy power parameters and the side length of the central square fragment are set. After fixing the contact part of the femtosecond laser on the eyeball and checking the boundaries of the pupil, the front and back surfaces of the lens with an optical coherence tomograph built into the laser device, they begin to determine the boundaries of the laser effect on the lens depending on its thickness and the width of the pupil. Then, using femtosecond laser energy, cuts are made in the lens. In this case, the laser initially makes incisions in the lens along four mutually perpendicular lines, which form nine fragments, of which a central square-shaped fragment with side lengths ranging from 1.0 to 3.0 mm is crushed by additional incisions, and four rectangular-shaped fragments and four triangular fragments the forms are located around the central fragment (Fig. 2). The anterior capsulorhexis and corneal incisions are then created using a laser. Next, the corneal incisions are opened in a standard manner, the anterior chamber is filled with viscoelastic, the anterior capsule is removed within the capsulorhexis, moderate hydrodissection and hydrodelineation of the lens are performed with the release of gas bubbles formed after laser exposure from the capsular bag. During subsequent ultrasonic emulsification of the lens, the central square most fragmented by the laser is first removed to its entire depth. Then the rectangular fragments are alternately fixed on the phaco needle with a vacuum (Fig. 3), pushed into the vacated central zone like a “desk drawer” and emulsified. Next, the remaining triangular fragments are removed one by one, then the surrounding soft lens masses are aspirated without the use of ultrasound.

The advantage of this method is the possibility of separating fragments from each other and their further removal within the capsular bag, which helps reduce the mechanical load on the capsule, the ligamentous apparatus of the lens and the iris.

An additional advantage is that, unlike the method of radial division of the nucleus, where laser cuts pass along the fibers of the lens, the cut lines of the presented pattern partially intersect the fibers, which provides easier further ultrasonic emulsification of fragments and reduces the energy load of ultrasound on surrounding tissues, mechanical load on the lens capsule, its ligamentous apparatus, and also to exclude intraoperative and postoperative complications associated with the stage of lens removal.

The invention is confirmed by the following clinical examples.

Clinical example 1.

Patient V., 73 years old. Diagnosis of the right eye: Incomplete complicated cataract. Before surgery: VisOD 0.1 does not correct. Intraocular pressure (pneumotonometry) OD = 16 mm Hg. Optical biometry OD = 24.21 mm

Anterior chamber depth OD = 2.54 mm. Lens thickness OD = 4.1 mm

Endothelial cell density OD = 1990 cells/mm2.

Status ophthalmicus: OD – The cornea is transparent, smooth, moist. The anterior chamber is of medium depth, the moisture is transparent. The pupil is round, 3.0 mm in diameter, and reacts well to light. Partial opacification of the lens in the region of the nucleus and along the posterior surface, NO/NC 3 (LOCSIII). The optic disc is pale pink, the boundaries are clear, the vessels are of normal caliber, the retina is not changed. The patient underwent femto-assisted cataract phacoemulsification using the lens fragmentation pattern. Using a femtosecond laser, four mutually perpendicular incision lines were made, forming nine fragments. The central square-shaped fragment was crushed with additional cuts. Next, the corneal incisions were opened in a standard manner, the anterior chamber was filled with viscoelastic, the anterior capsule was removed within the capsulorhexis, and moderate hydrodissection and hydrodelineation of the lens was performed with the release of gas bubbles formed after laser exposure from the capsular bag. During subsequent phacoemulsification of the lens, the central square, which was most crushed by the laser, was first removed to its entire depth. Then the rectangular fragments were alternately fixed on the phaco needle with a vacuum and pushed into the vacated central zone, where they were removed using ultrasound. Next, the remaining triangular fragments and surrounding lens masses were removed one by one.

The lens was removed without complications. An Ocuflex intraocular lens (optical power +20.5D) was implanted into the capsular bag.

Upon discharge on the next day: Vis OD 0.9 sph (-) 0.25D = 1.0

Intraocular pressure (pneumotonometry) OD = 15 mmHg

Endothelial cell density OD = 1972 cells/mm2

Status ophthalmicus: OD – The cornea is transparent, smooth, moist, the incision area is clean. The anterior chamber is deep, the moisture is transparent. The pupil is round, 3.0 mm in diameter, and reacts well to light. The IOL is in the capsular bag, the position is correct. The optic disc is pale pink, the boundaries are clear, the vessels are of normal caliber, the retina is not changed. The load on the lens capsule, its ligamentous apparatus, iris and cornea is reduced. Intraoperative and postoperative complications associated with the stage of lens removal were excluded.

Clinical example 2.

Patient V., 39 years old. Diagnosis of the right eye: high degree of hypermetropia, low degree of amblyopia. Before surgery: VisOD 0.05 (+) 6.0D = 0.7

Autorefractometry OD sph (+)6.25Dcyl (-)0.5D ax 92. Intraocular pressure (pneumotonometry) OD = 18 mm Hg. Optical biometry OD = 21.30 mm. Anterior chamber depth OD = 2.62 mm. Lens thickness OD = 4.3 mm. Endothelial cell density OD = 2720 cells/mm2.

Status ophthalmicus: OD – The cornea is transparent, smooth, moist. The anterior chamber is of medium depth, the moisture is transparent. The pupil is round, 3.0 mm in diameter, and reacts well to light. The lens is transparent, NO/NC 0 (LOCSIII). The optic disc is pale pink, the boundaries are clear, the vessels are of normal caliber, the retina is not changed. The patient underwent femto-assisted lens phacoemulsification for refractive purposes using the lens fragmentation pattern. Using a femtosecond laser, four mutually perpendicular incision lines were made, forming nine fragments. The central square-shaped fragment was crushed with additional cuts. Next, the corneal incisions were opened in a standard manner, the anterior chamber was filled with viscoelastic, the anterior capsule was removed within the capsulorhexis, and moderate hydrodissection and hydrodelineation of the lens was performed with the release of gas bubbles formed after laser exposure from the capsular bag. During the subsequent phacoemulsification of the lens, the central square, which was most crushed by the laser, was first removed to its entire depth by aspiration without the use of ultrasound. Then the rectangular fragments were alternately fixed on the phaco needle with a vacuum and advanced into the vacated central zone, where they were then aspirated without the use of ultrasound. The lens was removed without complications. A Rayner intraocular lens (optical power +28.5D) was implanted into the capsular bag.

Upon discharge the next day: Vis OD 0.8 does not correct

Autorefractometry OD sph (+)0.25D cyl (-)0.5D ax 96

Intraocular pressure (pneumotonometry) OD = 16 mmHg

Endothelial cell density OD = 2712 cells/mm2

Status ophthalmicus: OD – The cornea is transparent, smooth, moist, the incision area is clean. The anterior chamber is deep, the moisture is transparent. The pupil is round, 3.0 mm in diameter, and reacts well to light. The IOL is in the capsular bag, the position is correct. The optic disc is pale pink, the boundaries are clear, the vessels are of normal caliber, the retina is not changed. The load on the lens capsule, its ligamentous apparatus, iris and cornea is reduced. Intraoperative and postoperative complications associated with the stage of lens removal were excluded.

Claims (1)

A method for fragmenting a lens using a femtosecond laser, including making incisions in the lens and grinding its center, characterized in that laser energy is used to make incisions in the lens as in FIG. 1 along four mutually perpendicular lines, which form nine fragments, of which a central square-shaped fragment with side lengths ranging from 1.0–3.0 mm is crushed by additional cuts, and four rectangular-shaped fragments and four triangular-shaped fragments are located around the central fragment, in this case, the depth and diameter of the area of the incision lines depend on the thickness of the lens and the width of the pupil.