Method of additional correction using lenticular extraction after previously performed keratorefractive lenticule extraction
The VISUMAX800 laser-based method for additional correction after keratorefractive lenticule extraction addresses the limitations of existing methods by increasing cap thickness and reducing lenticule diameter, achieving precise and minimally invasive correction with reduced trauma and rapid recovery.
Patent Information
- Authority / Receiving Office
- RU · RU
- Patent Type
- Patents
- Current Assignee / Owner
- SHILOVA TATYANA YUREVNA
- Filing Date
- 2025-09-11
- Publication Date
- 2026-07-01
AI Technical Summary
Existing methods for additional correction after keratorefractive lenticule extraction, such as SMILE, Femto LASIK, and PRK, increase the risk of dry eye syndrome and reduce corneal biomechanical strength, while methods like SPS require specific laser energy adjustments and are limited by initial cap thickness.
The method uses the VISUMAX800 laser to shape the inferior refractive surface, increase the superior cap thickness by 5-10 microns, decrease the secondary lenticule diameter by 0.2 mm, and program the incision pattern in spiral-in mode, allowing precise extraction through the initial incision without increasing tissue removal or energy, maintaining corneal integrity.
This approach enhances correction accuracy, reduces trauma, and ensures rapid visual recovery by preserving corneal tissue and minimizing procedure duration to less than 4 seconds, applicable to various lenticular extraction methods.
Abstract
Description
[0001] The invention relates to ophthalmology and is intended for additional correction by the lenticular extraction method after previously performed keratorefractive lenticule extraction.
[0002] One of the fundamentally new areas of refractive surgery is the use of femtosecond lasers to form an intrastromal lenticule with a given geometry and then extract it through a 2-4 mm microincision (CRE). The VisuMax500 (CarlZeiss, Germany) was the first such laser, with which W. Sekundo and M. Blum performed the first refractive lenticule extraction (ReLEx - Refractive Lens Extraction) in 2007, calling it SMILE (Small-Incision Lenticule Extraction). In this procedure, instead of a superficial corneal flap, a "cap" consisting of intact superficial layers is formed over the formed lenticule, commonly referred to as a cap.
[0003] The refinement of ZEISS SMILE® (ReLEx SMILE) technology has led to the creation of SMILE pro technology – an innovative method of laser vision correction performed using the VISUMAX® 800 femtosecond laser, equipped with a robotic system. While the SMILE® vision correction procedure lasts 25-30 seconds, the SMILE® pro method takes less than 10 seconds. This rapid intervention significantly reduces the risk of developing dry eye syndrome, while the VISUMAX® 800 laser ensures the highest correction accuracy through the use of innovative CentraLign® and Oculigne® technologies – eye movement tracking and semi-automated centration.
[0004] At the same time, there are already a number of competing femtosecond lasers capable of forming an optical intrastromal lens (lenticule): SmartSight ATOS (from Schwind) and CLEAR ZLDV8 (from Ziemer). A distinctive feature that unites these technologies is the fact that the upper portion of the formed lenticule is refractively neutral, roughly parallel to the patient's corneal surface.
[0005] Thus, after lenticule extraction by any of the above methods, the patient's upper layers of the cornea remain intact, and there is a horizontal plane with a diameter equal to the previously programmed cap size.
[0006] Over time, some patients after CREOL require additional correction of the resulting myopia and astigmatism as a result of regression or increase in the anterior-posterior axis of the eye due to the progression of myopia.
[0007] The following methods are known for additional correction after SMILE:
[0008] Repeat SMILE after SMILE, performed at a higher level by reducing the cap thickness and increasing the neutral optic layer, thereby removing a greater thickness of the stroma and reducing corneal biomechanics. Furthermore, this procedure increases the risk of dry eye syndrome. Furthermore, energy levels must be adjusted to indicate the transition to the superior plane, and this procedure lasts approximately 15 seconds. Patented only for SMILE technology.
[0009] Circle is a standard Zeiss module for additional correction for converting a "cap" into a flap. The micro-incision left after the initial surgery is expanded to the flap using a femtosecond laser, followed by corneal ablation (evaporation) to the desired shape using an excimer laser, similar to the popular Femto LASIK correction method. This method eliminates microinvasiveness, which is why it is associated with decreased biomechanical properties of the cornea, dry eye syndrome, epithelial ingrowth under the flap, micro- and macrostriae of the flap, and other problems, increasing the invasiveness of the procedure.
[0010] If the cap (the cap remaining after SMILE) is sufficiently thick, a classic Femto LASIK procedure is performed to form a new cap within the cap. In this case, the cap diameter can be larger than the cap diameter. Alternatively, a femtosecond laser is used to perform a circumferential incision, converting the cap into a cap of the same diameter. These cases also involve the full range of risks associated with the transition to femtosecond laser valve technology, as described earlier.
[0011] Additional correction can be performed using the well-known and long-established PRK procedure with appropriate corneal parameters (https: / / www.clinicaspectr.ru / ). This technique carries a risk of subepithelial scarring (haze), dry eye syndrome, decreased correction accuracy due to epithelial hyperplasia, and thinning of the upper strong stromal layers.
[0012] However, all of the above methods reduce the signs of microinvasiveness, reduce the biomechanical strength of the cornea and increase the risk of developing dry eye syndrome.
[0013] The closest analogue of the proposed method is the SPS method proposed by O.V. Pisarevskaya and co-authors https: / / cyberleninka.ru / article / n / smile-posle-smile-novyyy-podhod-k-korrektsii-ostatochnoy-miopii?ysclid=mfa4al3t2x742772771. The essence of the technology lies in the use of the interface previously formed during the SMILE operation as the anterior surface of the lenticule. - During the procedure, the neutral optical layer of the cornea is increased from 15 μm to 30 μm, the thickness of the corneal flap is reduced from 130 μm to 115 μm, and the diameter of the optical zone from 7.0 mm to 6.5 mm.
[0014] However, the main drawback of this method is that it requires a 15-micron reduction in corneal flap thickness, which critically reduces the ability to reach the previously formed interface. Since epithelial remodeling always occurs after correction, increasing its thickness, the cap thickness becomes greater than the value programmed for the initial correction. Thus, the reduction leads to profile mismatches even with increasing tissue thickness due to the significant increase in the lateral edge of the lenticule. Furthermore, this method is not applicable to initial cap thicknesses of 110 microns or less, since minus 15 microns in this case amounts to less than 100 microns, which is unprogrammable. This method is also only applicable to the VisuMax500 and SMILE technology and requires changing the laser energy parameters to stop the laser between stages, increasing the duration of the procedure.
[0015] The objective of the proposed invention is to develop a method for additional correction of postoperative ametropia after keratorefractive lenticule extraction using the SMILE Pro method.
[0016] The technical result of the proposed method is to increase the accuracy of additional correction while reducing trauma. This is achieved by shaping the inferior refractive surface using the VISUMAX800 laser, increasing the superior cap thickness by 5-10 microns depending on epithelial hyperplasia, decreasing the secondary lenticule diameter by 0.2 mm, and programming the incision pattern of the superior lenticule profile in spiral-in mode.
[0017] The technique maintains the principle of microinvasiveness and allows for the extraction of newly formed lenticule after primary correction using any lenticular extraction method with a refractively neutral upper surface. This preserves corneal tissue without increasing the amount of tissue removed or the energy applied to it. The incision formation mode, from outside to inside, allows for visualization of the beginning of stage 3 and timely laser interruption, which takes no more than 3-4 seconds, depending on the diameter of the newly formed lenticule. Removal is performed through the incision previously created during primary correction. This, in addition to more precise correction, reduces the trauma of the method.
[0018] The residual stromal thickness (RST) should be no less than 250 microns after additional lenticule extraction, and the total thickness of the removed stroma should not exceed 40%, which is a requirement for all lenticular surgery methods. The method is performed as follows.
[0019] The secondary lenticule is removed through the previously made lenticule extraction incision using a VISUMAX® 800 femtosecond laser. The upper profile of the secondary lenticule is the junction of the upper and lower profiles after removal of the primary lenticule. The cutting pattern for the upper profile of the secondary lenticule is programmed in spiral-in mode. The secondary lenticule diameter is reduced by 0.2 mm relative to the primary lenticule diameter, and the cap thickness is increased by 5-10 microns depending on the extent of epithelial hyperplasia.
[0020] The method was tested on five patients. The results demonstrated its versatility, clinical efficacy, safety, repeatability, and rapid visual recovery.
[0021] Example 1.
[0022] Patient L., 30 years old. A year ago, CLEAR refractive surgery was performed.
[0023] The patient complained of decreased quality and acuity of distant vision and deterioration of night vision.
[0024] Initial refraction before KREL:
[0025] OD: sph -4.5 cyl-1.5ax 100°
[0026] OS: sph -4.75 cyl -1.25 ah 90°
[0027] At the time of preoperative examination:
[0028] OD: sph-1.0 cyl -0.5 ah 105°
[0029] OS: sph-1.5 cyl -0.25 ah 95°
[0030] UCVA OD=0.1, BCVA=1.0, UCVA OS=0.05, BCVA=1.0
[0031] OD Keratometry: K1 40.50 D, K2 41.00 D, K average 40.75 D
[0032] OS Keratometry: K1 40.75 D, K2 41.00 D, K average 40.88 D
[0033] Pachymetry: OD=509 microns, OS=512 microns.
[0034] Primary correction data:
[0035] Both eyes: cap thickness 120 microns, optical zone 6.5 mm, cap diameter 7.5 mm. Pachymetry OD - 587 microns, OS - 596 microns, residual stroma OD -384 microns, OS - 383 microns.
[0036] Since the patient had undergone primary CLEAR correction in another clinic and there was no primary data, the thickness of the “cap” was measured in one block - stroma and epithelium on the OCT Triton device.
[0037] Correction of myopia and astigmatism regression (additional correction) was performed on both eyes using the stated method.
[0038] Further correction was performed: the secondary lenticule was removed using a VISUMAX® 800 femtosecond laser, with the upper profile of the secondary lenticule being the junction of the upper and lower profiles after the removal of the primary lenticule. The cutting pattern of the upper profile of the secondary lenticule was programmed in the spiral-in mode, the diameter of the secondary lenticule was reduced by 0.2 mm compared to the diameter of the primary lenticule, and the cap thickness was increased by 56 microns.
[0039] Data after correction:
[0040] Both eyes: cap thickness 125 microns, optical zone 6.3 mm, cap diameter 7.5 mm. Lateral lenticule thickness 15 microns. Lenticular thickness for additional correction: OD - 40 microns, OS - 45 microns.
[0041] Residual stroma OD - 344 microns, OS - 338 microns.
[0042] Spherical component and astigmatic component are enhanced by +10%.
[0043] Programming the cutting pattern of the upper profile of the lenticule in the spiral-in mode, stop at 4 seconds.
[0044] Observation on the 1st day after correction
[0045] Vis OD - 1.0
[0046] Vis OS-1.0
[0047] Autorefractometry:
[0048] OD: sph 0.25 cyl -0.25 ah 100°
[0049] OS: sph 0.0 cyl -0.25 ah 93°
[0050] The cornea is clear in both eyes, with a stromal reaction of grade 0. Subjectively, the patient is highly satisfied. Refraction is stable over a 6-month follow-up period. Example 2.
[0051] Patient K., 37 years old. Correction of myopia and astigmatism regression was performed on the right eye 6 years after SMILE surgery performed in another clinic.
[0052] Initial refraction before KREL:
[0053] OD: sph -7.0 cyl-1.0 ah 55°
[0054] OS: sph -4.5 cyl-1.5 ah 95°
[0055] At the time of preoperative examination before further correction:
[0056] OD: sph -2.5 cyl-1.0 ah 35°
[0057] OS: sph 0.5 cyl-1.0 ah 95°
[0058] UCVA OD=0.1, BCVA=1.0, UCVA OS=0.8, BCVA=1.0
[0059] OD Keratometry: K1 39.75 D, K2 40.50 D, K average 40.25 D
[0060] Pachymetry: OD=510 microns.
[0061] Primary correction data:
[0062] Both eyes: cap thickness 100 microns, optic zone 6.6 mm, cap diameter 7.6 mm. Pachymetry OD - 612 microns, residual stroma OD - 402 microns. Additional correction was performed: the secondary lenticule was removed using a VISUMAX® 800 femtosecond laser, while the upper profile of the secondary lenticule was the junction of the upper and lower profiles after removal of the primary lenticule. The cutting pattern of the upper profile of the secondary lenticule was programmed in the spiral-in mode, and the diameter of the secondary lenticule was reduced by 0.2 mm relative to the diameter of the primary lenticule, and the cap thickness was increased by 10 microns. In the second case, the initial parameters were known, so the thickness of the epithelium measured on the SOLIX OST was added to the known thickness of the previously specified cap.
[0063] SMILE PRO post KLEX data:
[0064] OD: cap thickness 105 microns, optical zone 6.3 mm, cap diameter 7.6 mm. Lateral lenticule thickness 15 microns. Lenticule thickness for additional correction: OD - 62 microns
[0065] Residual stroma OD - 360 microns.
[0066] Spherical component and astigmatic component are enhanced by +10%.
[0067] Programming the cutting pattern of the upper profile of the lenticule in the spiral-in mode, stopping at 4.5 seconds.
[0068] Observation on the 1st day after correction
[0069] Vis OD-1.0
[0070] Autorefractometry:
[0071] OD: sph 0.5 cyl -0.5 ah 30°
[0072] The cornea is transparent, the stromal reaction is grade 0.
[0073] Subjectively, high patient satisfaction. Refraction is stable after a 4-month follow-up.
[0074] Thus, the proposed method provides the possibility of additional correction of refractive errors in patients after previously performed keratorefractive lenticule extraction using the microinvasive SMILE PRO method.
Claims
A method of additional correction by the lenticular extraction method after previously performed keratorefractive extraction of the lenticule, characterized in that the secondary lenticule is removed through a previously performed incision for lenticule extraction using a VISUMAX® 800 femtosecond laser, wherein the upper profile of the secondary lenticule is the junction of the upper and lower profiles after removal of the primary lenticule, programming the pattern of cuts of the upper profile of the secondary lenticule is carried out from the outside inward in the spiral-in mode, the diameter of the secondary lenticule is reduced by 0.2 mm relative to the diameter of the primary lenticule, and the thickness of the cap is increased by 5-10 microns depending on the magnitude of epithelial hyperplasia.