Safety and efficacy of VisuMax® circle patterns for flap creation and enhancement following small incision lenticule extraction
© Chansue et al. 2015
Received: 24 September 2015
Accepted: 11 December 2015
Published: 26 December 2015
The purpose of this case series is to evaluate the safety and efficacy of VisuMax® Circle patterns in eyes that have undergone small incision lenticule extraction, thus creating a flap to perform an enhancement procedure or residual lenticule extraction.
This prospective, single center, case study series evaluated the use of a VisuMax® Circle pattern to create a corneal flap following small incision lenticule extraction. Patients were treated and followed at TRSC International LASIK Center (Bangkok, Thailand) for 3 months to assess the efficacy and safety of the procedure. Efficacy was determined by the surgeon’s ability to lift the created corneal flap.
The study enrolled 28 eyes. Twenty-seven underwent the VisuMax® Circle pattern procedure for refractive enhancement, and one for residual lenticule extraction. In 100 % of cases (28 eyes) the lifting of the flap was possible, as planned. In all cases of refractive enhancement (27 eyes) by laser in situ keratomileusis (LASIK), the exposure of the stromal bed was sufficient for the necessary excimer laser ablation. No eyes lost two or more Snellen lines of corrected distance visual acuity (CDVA) and no procedure or flap-related complications or serious adverse events occurred.
This initial case series demonstrates that VisuMax® Circle pattern is efficacious and a suitable method to create a corneal flap for enhancement, following small incision lenticule extraction.
KeywordsSmall incision lenticule extraction SMILE Lenticule Residual lenticule extraction Flap creation Circle pattern Refractive enhancement Femtosecond laser Refractive surgery
New technologies such as femtosecond lasers are creating a paradigm shift in the surgeon’s ability to perform refractive correction with improved results [1–5]. The development of small incision lenticule extraction (SMILE) as a new, flapless procedure has been a major innovation in corneal refractive surgery. This technique, performed using Refractive Lenticule Extraction (ReLEx®) on the VisuMax® (Carl Zeiss Meditec, Jena, Germany) platform, allows for refractive correction without the need to create a corneal flap. Rather, a small side cut incision, less than 4 mm in size is created at an approximate depth of 80 to 160 μm in the cornea for lenticule extraction. This gives access to the intrastromal pocket created by the preceding lenticule cuts. By creating an intrastromal pocket rather than the traditional flap, surgeons can eliminate associated complications including incomplete and irregular flap cuts, thin flaps, buttonholes, and free caps.
In the past, enhancement following ReLEx® SMILE was a challenge and a number of possible approaches have been considered. Surgeons may contemplate surface ablation if such ablation does not reach the pocket interface. An intraocular lens could be inserted to correct a larger refractive error if the residual stroma is inadequate for photoablation. Other options for the surgeon can either be laser in situ keratomileusis (LASIK), anterior to the SMILE pocket or an additional SMILE procedure, anterior (or posterior, depending on how deep the SMILE pocket is situated) to the initial one. Carl Zeiss Meditec has recently provided an additional option with the development of a series of four circle patterns, programmed within the VisuMax® platform, which can be utilized to create a corneal flap after previous refractive correction with ReLEx® SMILE. This strategy allows for the original SMILE incision pocket to be converted into a LASIK-like flap that can be easily lifted to allow for stromal ablation of the residual refractive error with an excimer laser. Intrastromal incisions include the creation of a lamellar ring, anterior, posterior or adjacent to the previous SMILE pocket cut; a side cut with a hinge and a junction cut from the inner edge of the lamellar ring to junction depths.
In 2013, Riau et al. investigated the use of four different VisuMax® circle patterns when they performed −6.00 D spherical correction using ReLEx® SMILE on six New Zealand white rabbits (12 eyes), and then 28 days later, one of the four circle patterns was used on each of the 12 eyes and evaluated for ease of flap lift . In that animal model, it was determined that pattern D, a lamellar ring adjacent to the cap cut, was the most optimal pattern for flap creation, and ultimately, SMILE re-treatment .
Here, we describe the four different VisuMax® circle patterns, which have been programmed to create a corneal flap. We also present the efficacy and safety results for 28 patients upon whom circle pattern D was utilized to create a flap for residual lenticule extraction or refractive enhancement by stromal excimer laser ablation after ReLEx® SMILE. We also discuss the other applications for which the circle patterns can be utilized. To our knowledge, this is the first report of the circle pattern use in human eyes.
This prospective clinical case study consisted of participants recruited from TRSC International LASIK Center. Each was provided written informed consent that explained the details of the procedure and study protocol in accordance with the principles of the Declaration of Helsinki. According to the Food and Drug Administration (FDA) Thailand, this study was considered clinical quality control and evaluation under CE mark status and therefore, ethical approval was not necessary. In order to be included, patients had to be a minimum of 18 years of age, had previously undergone ReLEx® SMILE and now had a residual refractive error from undercorrection, overcorrection or regression, including residual and/or consecutive astigmatism, that necessitated planned circle pattern treatment and LASIK touch-up. Additionally, a patient with residual lenticule following ReLEx® SMILE, which required extraction was also included. For patients with a residual refractive error, the current refraction had to be stable for at least 3 months. The determination if the previous SMILE incision could be opened, depended on whether one of the two interfaces above or below the lenticule could successfully be separated. Patients had to have the ability to attend postoperative assessment appointments at 1 day, 1 week, 1 month, and 3 months. Patients were excluded if they had ocular conditions, other than residual myopia, consecutive hyperopia with or without residual or consecutive astigmatism following the original ReLEx SMILE procedure.
Preoperatively, all post-ReLEx SMILE patients underwent a complete eye examination, which included objective and manifest refractions, visual acuity (ETDRS LogMAR chart), scotopic pupil size evaluation (Colvard Light-Amplification Pupillometer, Oasis Medical, San Dimas, CA), computerized corneal topography (Orbscan, Bausch & Lomb, Bridgewater, NJ), pachymetry (DGH Technology, Inc., Exton, PA), wavefront analysis (Wasca Analyzer, Wavefront Sciences, Albuquerque, NM), keratometric measurements (Sim-K values from Orbscan), and slit-lamp examination.
The first day after the circle enhancement procedure, patients had their uncorrected visual acuity assessed, a slit-lamp evaluation performed, and any complications or adverse events examined. At each of the remaining postoperative appointments (1 week, 1 month, 3 months) patients were assessed for corrected distance visual acuity, uncorrected visual acuity, objective and manifest refractions, computerized corneal topography, wavefront analysis, keratometric measurements, and slit-lamp examination.
All patients had previously undergone ReLEx® SMILE for myopic and/or astigmatism correction at our center and it was determined that further correction would be beneficial. Thus, the circle pattern procedure was performed to create a flap from the original SMILE pocket. In one eye the circle pattern procedure was planned to remove residual lenticule that was present.
The primary endpoint of this series was to evaluate the ability of the surgeon to create a flap using the circle pattern and successfully lift this flap to perform refractive enhancement to the original SMILE procedure. In enhancement cases, the stromal bed should be of sufficient quality to perform LASIK. Safety of the use of the circle pattern was also evaluated, and assessments of safety included the loss of 2 or more Snellen lines of CDVA  after 3 months, compared to preoperative assessment, and any procedural or flap complications including rupture or perforation.
All patient demographic and baseline information as well as outcome measurement data were collected on paper case report forms, which subsequently were entered into an Excel spreadsheet (Microsoft Corporation, Redmont, WA). Descriptive analyses were performed using the data analysis features of Excel. Analysis of visual acuity results were performed by calculating the geometric mean with standard deviation into logMAR format from Snellen examination results.
Preoperative demographics of the study population
28 (12 OD/16 OS)
46 % / 54 %
Mean ± SD
36 ± 11 years
19 to 57 years
Manifest Spherical Equivalent (D)
−0.74 ± 0.80
0.375 to −2.875
Manifest Cylinder (D)
−0.7 ± 0.34
0 to −1.25
In one eye in this series, the femtosecond laser was incorrectly programmed, and the plane was cut at an incorrect depth, necessitating the use of micro-scissors to connect the planes. This was performed uneventfully, and healing process and visual results are similar to those of the other cases. There were no serious adverse events or serious side effects reported.
At three months post-operatively, uncorrected visual acuity was 20/40 or better in 100 % of the eyes, and 20/20 or better in 95.8 % of the 24 eyes that were corrected for distance vision. Residual refractive error (spherical equivalent) averaged +0.1 D.
ReLEx® SMILE has been used clinically over the past few years to provide patients with refractive correction by means of lenticule extraction . By leaving the cornea intact, surgeons are able to maintain its biomechanical stability, while protecting more of the nerve fibers. Studies have demonstrated the safety, predictability and efficacy of SMILE in the correction of myopia [1–5, 7, 9]. In a recent study by Hjortdal et al., they found that 3 months after patients were treated with SMILE, 94 % were within ±1.00 D . Similarly, Sekundo and colleagues found that 95.6 % of eyes in their cohort were within ±1.00 D . Reported predictability of LASIK ranges widely from 78.2 % up to 96.7 % [10, 11] with enhancement procedures typically being performed with flap lift LASIK or surface ablation [12, 13]. The higher rates of predictability anticipated with SMILE suggest that enhancement rates will be lower than with LASIK. Because SMILE does not cut a full circumferential flap there is improved maintenance of corneal integrity, and refractive regression is not anticipated to be as common as it is in LASIK. Studies have also shown SMILE procedures deliver stable results with minimal, non-significant refractive regression up to 6 months postoperatively [1–5, 8]. The good predictability, stability and efficacy results suggest that SMILE is a viable choice for refractive correction. Previously, for the few patients that did require enhancement, options were limited to an implantable lens or excimer laser surface ablation (PRK).
In our series, we present the option of using the circle-created flaps for eyes previously treated with SMILE. Riau et al., who first evaluated the use of the circle patterns in rabbit eyes, determined that pattern D, a lamellar ring adjacent to the cap cut, was the most optimal pattern for flap creation and ultimately SMILE re-treatment . In our center, pattern D was also the pattern of choice because choosing to create a flap at the same depth as the original cut seemed to be the most appropriate in all cases.
In all of our patients, lifting the circle-created flap through the use of pattern D could be easily achieved, similar to lifting a femtosecond LASIK flap. The study by Riau et al. also evaluated the ease of flap lift, comparing the four different circle patterns on rabbit eyes. They determined that patterns A and D were the easiest to lift, and the resulting flap bed remained smooth and undisrupted .
Flap thickness compared to settings in previous ReLEx SMILE surgeries
Flap thickness (μm)
Cap thickness setting in the previous SMILE procedure (μm)
As this is the initial report of the clinical use of circle pattern D on human eyes following SMILE, we acknowledge some limitations. Here we only looked at the technical efficacy of the procedure for these patients and the presence of any safety concerns. We intend to further investigate and analyze other variables, such as OCT data, confocal microscopy and patient satisfaction, to provide additional insight into this procedure. We feel that further study needs to be conducted to determine if the time period between the initial SMILE procedure and the Circle procedure influences the ease of flap lift.
Although this initial series only followed 28 eyes for a period of 3 months, we feel that it provides useful initial information and demonstrates that the VisuMax® circle pattern D is technically feasible and is a suitable method to create a corneal flap for enhancement following SMILE.
The authors would like to thank and acknowledge the valuable contributions to this paper of the following colleagues at TRSC International LASIK Center, Bangkok, Thailand: Pavika Thammano, MD, Sabong Srivannaboon, MD, Pichit Naripthaphan, MD, Suchai Woraamornchot, MD, Varintorn Chuckpaiwong, MD, Chareenun Chirapapaisan, MD, and Pimsiri Chamanan, MD.
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