Safety and efficacy of VisuMax® circle patterns for flap creation and enhancement following small incision lenticule extraction

Central corneal distortion after small-incision lenticule extraction

A 33-year-old woman with a prior history of small-incision lenticule extraction (SMILE) presented with gradual deterioration of vision in her right eye since the surgery. She had undergone bilateral SMILE for myopic correction (-7.00 diopters [D] in the right eye and -6.00 D in the left eye) 3 weeks prior. SMILE was performed with a Zeiss VisuMax femtosecond laser system, with a cap thickness of 120 µm, a cap diameter of 7.50 mm, and a lenticule diameter of 6.50 mm. At the completion of the surgery, loose epithelium was noted at the SMILE incision bilaterally, and bandage contact lenses were placed in both eyes. On the first postoperative day, the patient's uncorrected distance visual acuity (UDVA) was 20/40 in both eyes. The bandage lenses were removed from both eyes, with the epithelium intact. At the first-week postoperative visit, her visual acuity was recorded as 20/30 in the right eye and 20/20 in the left eye. She noticed her vision in the right eye was not as sharp as that in her left eye. She denied experiencing any pain, redness, or ocular surface irritations. She was advised to return to the clinic for a 1-month postoperative visit and continue with aggressive lubrication in both eyes. However, a week later, the patient returned for an emergency visit, citing significant central visual distortion in the right eye and difficulty working on the computer. At this visit, her UDVA and corrected distance visual acuity (CDVA) was 20/50 in the right eye and 20/15 in the left eye at both near and far distances. A slitlamp examination revealed mild central changes in the right eye. She once again denied any pain, redness, or irritation. She was advised to continue with artificial tears and return to the office in 1 week for further observation of the central distortion in her right eye. Upon returning to the clinic at the third postoperative week, the patient still complained of central visual changes in the right eye, with a visual acuity of 20/70. Further slitlamp examination revealed a nonspecific central haze in the same eye, but there was no corneal staining or signs of epithelial defects. Anterior segment ocular coherence tomography (AS-OCT) and NIDEK topography were performed, showing the same central distortion in the right eye (Figures 1 and 2JOURNAL/jcrs/04.03/02158034-202311000-00016/figure1/v/2023-10-18T004638Z/r/image-tiffJOURNAL/jcrs/04.03/02158034-202311000-00016/figure2/v/2023-10-18T004638Z/r/image-tiff). Based on the examination and images provided, what is your working medical diagnosis? What other medical conditions are in your differential diagnosis? What medical and/or surgical interventions would you recommend, if any?

Visual outcomes of early enhancement following small incision lenticule extraction versus laser in situ keratomileusis

Purpose

To compare visual outcomes of early enhancement following small incision lenticule extraction (SMILE) versus laser in situ keratomileusis (LASIK).

Methods

Retrospective analysis of eyes (patients operated in the setting of a tertiary eye care hospital between 2014 and 2020) requiring early enhancement (within one year of primary surgery) was conducted. Stability of refractive error, corneal tomography, and anterior segment Optical Coherence Tomography (AS-OCT) for epithelial thickness was performed. The correction post regression was done using photorefractive keratectomy and flap lift in eyes, wherein the primary procedure was SMILE and LASIK, respectively. Pre- and post enhancement corrected and uncorrected distance visual acuity (CDVA and UDVA), mean refractive spherical equivalent (MRSE), and cylinder were analyzed. IBM SPSS statistical software.

Results

In total, 6350 and 8176 eyes post SMILE and LASIK, respectively, were analyzed. Of these, 32 eyes of 26 patients (0.5%) post SMILE and 36 eyes of 32 patients (0.44%) post-LASIK required enhancement. Post enhancement (flap lift in LASIK, and PRK in SMILE group) UDVA was logMAR 0.02 ± 0.05 and 0.09 ± 0.16 (P = 0.009), respectively. There was no significant difference between the refractive sphere (P = 0.33) and MRSE (P = 0.09). In total, 62.5% of the eyes in the SMILE group and 80.5% in the LASIK group had a UDVA of 20/20 or better (P = 0.04).

Conclusion

PRK post SMILE demonstrated comparable results to flap lift post LASIK and is a safe and effective approach for early enhancement post SMILE.

The impact of different corneal refractive surgeries on binocular dynamic visual acuity

Purpose

To investigate the influence of different corneal refractive surgeries on dynamic visual acuity (DVA), and explore its potential influence factors.

Methods

This was a prospective non-randomized study. Adult myopic patients undergoing bilateral laser-assisted sub-epithelial keratomileusis (LASEK), femtosecond laser-assisted in situ keratomileusis (FS-LASIK), or small incision lenticule extraction (SMILE) with Plano refraction target were enrolled. Uncorrected and corrected distance visual acuity (UDVA/CDVA), manifest refraction and binocular optotype-moving DVA of 40 and 80 degrees per second (dps) were evaluated pre-operatively and post-operatively up to 3 months.

Results

The study included 264 eyes of 132 subjects, with an average age of 27.0 ± 6.7 years, and females accounted for 59% of the participants. Significant improvement was observed at the 3-month visit for 40 dps (SMILE, P = 0.001; LASEK, P = 0.006; FS-LASIK, P = 0.010) and 80 dps (SMILE, P = 0.011; LASEK, P = 0.025; FS-LASIK, P = 0.012) DVA. Adjusting for pre-operative DVA, there was no significant difference in DVA among groups at 3 months post-operatively (P > 0.05 for multiple comparisons). Overall, multiple linear models demonstrated that post-operative DVA at 3 months was correlated with pre-operative DVA (40 dps, β = 0.349, P = 0.001; 80 dps, β = 0.447, P < 0.001), pre-operative spherical equivalent (40 dps, β = 0.311, P = 0.003; 80 dps, β = 0.261, P = 0.009) and post-operative UDVA (40 dps, β = -0.224, P = 0.024; 80 dps, β = -0.188, P = 0.05).

Conclusion

Dynamic visual acuity at 3 months post-operatively of the three corneal refractive surgeries was better than that before the surgery in adult myopic patients, and there was no significant difference among different surgical techniques. Post-operative DVA at 3 months was found correlated with pre-operative DVA, pre-operative SE, and post-operative UDVA. With further improvement, DVA could be a promising functional visual indicator for myopic patients undergoing refractive surgeries.

Photorefractive Keratectomy Enhancement (PRK) After Small-Incision Lenticule Extraction (SMILE)

Purpose

To determine rates of enhancement and visual prognosis following photorefractive keratectomy (PRK) enhancement of small-incision lenticule extraction (SMILE).

Patients and Methods

This retrospective, single-site study reviewed all cases of primary SMILE at Hoopes Vision in Draper, Utah between March 14, 2017 and April 8, 2022 to identify any cases that required follow-up enhancement. Primary SMILE was performed using Visumax 500 kHz femtosecond laser (Carl Zeiss Meditec, Jena, Germany). All enhancements were performed with alcohol-assisted PRK, using a WaveLight EX500 excimer laser (Alcon Laboratories, Inc., Fort Worth, TX).

Results

Four hundred and five eyes underwent primary SMILE, of which 15 later underwent PRK enhancement (enhancement rate of 3.7%). No significant difference in pre-SMILE data was identified between the enhancement and non-enhancement groups. The average age of those who underwent PRK enhancement was 33.8±6.3 years old and ranged from 25 to 45. Following primary SMILE, 13 eyes (87%) had an uncorrected distance visual acuity (UDVA) of 20/40 or better, and none had a UDVA of 20/20 or better. After one year of post-enhancement follow-up, all eyes had a UDVA of 20/40 or better, and 13 eyes (87%) had a UDVA of 20/20 or better (Figure 1). All were within one diopter of target spherical equivalent (SEQ), 13 (87%) were within 0.50 D, and 10 (67%) were within 0.25 D. Of those with 12-month follow-up data, none had UDVA worse than corrected distance visual acuity (CDVA), and none had lost lines of CDVA. Efficacy and safety indices were 1.03 and 0.99, respectively.

Conclusion

Following SMILE, ophthalmologists may anticipate an enhancement rate of one to seven percent. In these cases, PRK is a safe and effective procedure for enhancement of SMILE.

SmartSurfACE transepithelial photorefractive keratectomy with mitomycin C enhancement after small incision lenticule extraction

Background

To evaluate predictability, stability, efficacy, and safety of transepithelial photorefractive keratectomy (TPRK) using smart pulse technology (SPT) (SmartSurface procedure) of Schwind Amaris with mitomycin C for correction of post small incision lenticule extraction (SMILE) myopic residual refractive errors.

Method

This study is a prospective, non-comparative case series conducted at a private eye centre in Ismailia, Egypt, on eyes with post-SMILE myopic residual refractive errors because of undercorrection or suction loss (suction loss occurred after the posterior lenticular cut and the creation of side-cuts; redocking was attempted, and the treatment was completed in the same session with the same parameters) with myopia or myopic astigmatism. The patients were followed up post-SMILE for six months before the SmartSurface procedure, and then they were followed up for one year after that. TPRK were performed using Amaris excimer laser at 500 kHz. The main outcomes included refractive predictability, stability, efficacy, safety and any reported complications.

Results

This study included 68 eyes of 40 patients out of 1920 total eyes (3.5%) with post-SMILE technique myopic residual refractive errors. The average duration between the SMILE surgery and TPRK was 6.7 ± 0.4 months (range 6 to 8 months). The mean refractive spherical equivalent (SE) was within ± 0.50 D of plano correction in 100% of the eyes at 12 months post-TPRK. Astigmatism of < 0.50 D was achieved in 100% of the eyes. The mean of the residual SE error showed statistically significant improvement from preoperative − 1.42 ± 0.52 D to 0.23 ± 0.10 D (P < 0.0001). Uncorrected distance visual acuity (UDVA) (measured by Snellen's chart and averaged in logMAR units) was improved significantly to 0.1 ± 0.07 (P < 0.0001). UDVA was 0.2 logMAR or better in 100% of the eyes, 0.1 logMAR or better in 91.2% of the eyes, and 0.0 logMAR in 20.6% of the eyes. Corrected distance visual acuity (CDVA) remained unchanged in 79.4% of eyes. 14.7% of eyes gained one line of CDVA (Snellen). 5.9% of eyes gained two lines of CDVA (Snellen).

Conclusion

Transepithelial photorefractive keratectomy using smart pulse technology with mitomycin C enhancement after SMILE is a safe, predictable, stable, and effective technique.

CIRCLE Software for Management of Epithelial Ingrowth After SMILE

PURPOSE

To report a novel therapeutic use of CIRCLE software (Carl Zeiss Meditec) to manage visually significant epithelial ingrowth following small incision lenticule extraction surgery (SMILE).

METHODS

Case series.

RESULTS

In this case series, the authors describe three eyes with progressive and visually significant epithelial ingrowth following an uneventful SMILE procedure. The management of epithelial ingrowth following SMILE is challenging, given the small access incision to the interface and the risk of incomplete removal. All cases were successfully managed by converting the SMILE cap into a flap using the CIRCLE software, which provided the necessary access to the original SMILE interface. Once the flap was lifted, the epithelial in-growth was completely debrided from the underlying stroma and undersurface of the flap, followed by a thorough interface wash. Postoperative recovery was uneventful, with no recurrence noted in any of the eyes.

CONCLUSIONS

Use of CIRCLE software provides a novel and unique approach to successfully treating vision-threatening epithelial ingrowth after SMILE. [J Refract Surg. 2021;37(11):776-780.].

Epithelial ingrowth following small incision lenticule extraction

A 27-year-old female patient came for a routine postoperative check-up, with a history of bilateral ReLEx small incision lenticule extraction (SMILE) surgery done 1.5 years back. On examination, epithelial ingrowth was noticed in the left eye at 8-9'o'clock position. Topography showed excess flattening in the area of ingrowth. Anterior Segment OCT showed hyper-reflectivity and was measured to be at a depth of 120 microns from the corneal surface. As the ingrowth appeared non-progressive, with no involvement of the pupillary axis and no visual complaints, no active intervention was done. Nonetheless, treatment options available include mechanical scraping and Nd:YAG laser procedure.

Surgical options for retreatment after small-incision lenticule extraction: Advantages and disadvantages

Since the inception of small-incision lenticule extraction (SMILE), many surgeons have speculated the lack of an adequate and standard retreatment procedure will impede its popularity. However, more than 1 million patients worldwide have had this surgery, with visual outcomes nearly equivalent to current laser in situ keratomileusis (LASIK) results. With the procedure's growing popularity, some patients will inevitably have a postoperative residual refractive error from regression, overcorrection, undercorrection, and astigmatic induction and will require retreatment. To our knowledge, literature reviewing major retreatment options is limited. Options include surface ablation, thin-flap LASIK, secondary small-incision lenticule extraction, and a cap-to-flap procedure (CIRCLE) in which a femtosecond laser is use to create cuts that convert the small-incision lenticule extraction cap into a LASIK flap. This review discusses major advantages and disadvantages of these options and compares the visual outcomes based on the existing literature. An algorithmic approach created from this analysis is presented to guide retreatment decision-making.

Refractive surprise: twice the SMILE

A 35-year-old man presented with decreased vision in his left eye following small incision lenticule extraction (SMILE) surgery. The refractive error after surgery was nearly twice his preoperative refractive error in the left eye. The patient was diagnosed as having a retained lenticule after SMILE surgery, which was folded on itself and was successfully managed by conversion to a flap. Postoperatively, the patient maintained good uncorrected visual acuity and a low refractive error, with the best spectacle corrected acuity of 20/20.

Astigmatism Correction Using SMILE

Small incision lenticule extraction (SMILE) was introduced in the recent decade for the treatment of myopia and myopic astigmatism. This flap-free technique has a high efficacy and safety profile and also carries potential advantages over laser in situ keratomileusis such as a better corneal biomechanical stability, reduction in dry eyes rate, and the avoidance of flap complications. However, there have been concerns regarding the precision of astigmatism correction that undercorrection has been reported to be apparent. Various factors that affect astigmatism correction have been identified in the literature. The purpose of this review is to discuss the factors that affect astigmatism correction in SMILE and several techniques to improve the refractive outcomes.

Enhancement Options After Myopic Small-Incision Lenticule Extraction (SMILE): A Review

PURPOSE

To provide an overview of the currently available retreatment methods after myopic small-incision lenticule extraction (SMILE).

DESIGN

Systematic literature review.

METHODS

The PubMed library was searched for articles containing the terms "small-incision lenticule extraction" and "enhancement" or "retreatment". The last search was performed on May 1, 2019.

RESULTS

In contrast to laser in-situ keratomileusis (LASIK), which can be retreated by a flap relift, repeat SMILE retreatment is currently not approved and only seldomly performed. As substitutes, surface ablation, cap-to-flap conversion using the CIRCLE program in the VisuMax platform, and thin-flap LASIK have been recently established. While all options offer safety and efficacy comparable to LASIK retreatments, each has its patient-specific advantages and disadvantages. While surface ablation preserves the flap-free approach of the primary procedure, the aspect of pain and a slow visual recovery might render it less attractive as compared with CIRCLE and thin-flap LASIK which offer quick recovery, however at the price of flap creation. Besides, each retreatment method generates specific tissue responses and has a different impact on corneal biomechanics, which is strongly dependent on the previous SMILE parameters, especially the cap thickness.

CONCLUSIONS

Refractive enhancement after SMILE is currently mostly performed by surface ablation, CIRCLE cap-to-flap conversion or thin-flap LASIK, which all offer safety and efficacy comparable to LASIK retreatments. In this review, a detailed overview over each method, its technical aspects, and specific advantages and disadvantages is given.

15-Month Visual Outcomes and Corneal Power Changes of SMILE in Treating High Myopia With Maximum Myopic Meridian Exceeding 10.00 D

PURPOSE

To evaluate the long-term visual and refractive outcomes, optical quality, and stability of the cornea and axial length after small incision lenticule extraction (SMILE) for the correction of high myopia with a maximum myopic meridian exceeding 10.00 diopters (D).

METHODS

Via a prospective cohort study, 53 eyes (53 patients) with a maximum myopic meridian exceeding 10.00 D were corrected with a VisuMax femtosecond laser (version 3.0; Carl Zeiss Meditec AG, Jena, Germany) at the Zhongshan Ophthalmic Center of Sun Yat-sen University. Refractive outcomes, aberrations, axial length, and corneal curvature were evaluated preoperatively and at 1, 3, and 15 months postoperatively.

RESULTS

At 15 months postoperatively, the efficacy and safety indexes were 0.91 ± 0.25 and 1.15 ± 0.18, respectively. A total of 72% of eyes were within ±0.50 D and 89% were within ±1.00 D of the attempted spherical equivalent, respectively. From 1 to 15 months postoperatively, the significant regression was -0.24 ± 0.28 D (P < .001) on manifest refraction and -0.43 ± 0.54 D (P < .001) on anterior corneal curvature. In addition, a significant increase of 0.20 µm (P = .016) was observed in the spherical aberration. No significant change was observed in posterior corneal curvature (P > .999), including mean keratometry or astigmatism, or in the ocular axis length from 1 to 15 months postoperatively (26.82 ± 0.93 and 26.82 ± 0.95 mm, respectively, P > .99).

CONCLUSIONS

SMILE had long-term safety, efficacy, and predictability when treating high myopia with a maximum myopic meridian exceeding 10.00 D. Both a manifest refraction regression of -0.24 D and a significant spherical aberration increase of 0.20 µm were observed between 1 and 15 months postoperatively, due to the increased anterior corneal curvature. [J Refract Surg. 2019;35(1):31-39.].

Corneal aberrations after small-incision lenticule extraction versus Q value-guided laser-assisted in situ keratomileusis

Previous studies compared ocular aberration and visual quality after small-incision lenticule extraction (SMILE) and Q value-guided femtosecond laser-assisted in situ keratomileusis (Q-FS-LASIK), but anterior corneal surface aberration properties are poorly known. This study aimed to compare the changes in anterior corneal surface aberration after SMILE versus Q-FS-LASIK.This was a prospective, observational cohort study. Patients with myopia and myopic astigmatism underwent SMILE or Q-FS-LASIK at Hangzhou MSK Eye Hospital between January 2015 and November 2015. High order aberration (HOA), primary spherical aberration (PSA), primary coma aberration (PCA), primary vertical coma aberration (PVCA), and primary horizontal coma aberration (PHCA) were assessed using pre- and postoperative Sirius scanning.Both surgery were associated with significant increases in postoperative HOA, PSA, and PCA (both groups P < .01). In the SMILE group (n = 51), the variations in HOA, PSA, and PCA were no longer significant after postoperative week 2 (P > .05). In the Q-FS-LASIK group (n = 73), the variations in HOA and PCA were no longer significant after postoperative day 1 (P > .05). In the SMILE group, the 3-month changes in PCA were not correlated with spherical, spherical equivalent (SE), and spherical plus cylinder measurements. Cylinder measurements were not correlated with HOA, PSA, and PCA. In the Q-FS-LASIK group, the 3-month changes in PCA correlated with spherical, SE, and spherical plus cylinder measurements.Both SMILE and Q-FS-LASIK resulted in an increase in HOA, PSA, and PCA at postoperative day 1, but Q-FS-LASIK introduced lower HOA and showed better stability. Spherical measurement was related to PSA.

CIRCLE Software for the Management of Retained Lenticule Tissue Following Complicated SMILE Surgery

PURPOSE

To describe the therapeutic use of CIRCLE software (Carl Zeiss Meditec, Jena, Germany) for the management of retained lenticule tissue after complicated small incision lenticule extraction (SMILE).

METHODS

Two patients were referred for consultation and treatment due to intraoperative complications during SMILE. In case 1, a black patch during laser delivery caused the lenticule to be torn irregularly from the undersurface during extraction and a sliver of it was retained in the pocket. Case 2 presented with false plane dissection and a completely retained lenticule on anterior segment optical coherence tomography. Both cases were managed using the CIRCLE software by converting the cap into a flap, thus making access to the interface possible.

RESULTS

In case 1, after lifting the flap a small sliver of tissue was found in the interface, which was dissected, following which a 20-µm phototherapeutic keratectomy was done to smooth the interface. In case 2, after lifting the flap the edge of the retained lenticule was identified by using an endoilluminator and the lenticule was separated and subsequently removed. Both cases showed significant improvement in uncorrected distance visual acuity, corrected distance visual acuity, and Objective Scatter Index score on day 1 after repair surgery.

CONCLUSIONS

CIRCLE software may be successfully used for managing retained lenticule tissue apart from performing enhancement after SMILE. [J Refract Surg. 2019;35(1):60-65.].

Outcomes of Re-treatment by LASIK After SMILE

PURPOSE

To report the outcomes of LASIK re-treatments after small incision lenticule extraction (SMILE).

METHODS

Retrospective review of all eyes to have undergone a re-treatment by LASIK after primary SMILE between September 2013 and January 2016. Thin-flap LASIK was used in most cases as long as sufficient tissue was available for safe flap creation between the maximum epithelial thickness and minimum cap thickness. Otherwise, the SMILE interface was converted into a LASIK flap by the Circle technique or side cut only. The multivariate nomogram for LASIK re-treatments was used, including sphere, cylinder, age, and primary spherical equivalent (SEQ) as variables. Patients were observed for 1 year after surgery and standard outcomes analysis was performed.

RESULTS

A total of 116 LASIK re-treatments were performed in a population of 2,643 consecutive SMILE procedures, indicating a re-treatment rate of 4.39%. Mean attempted SEQ was -0.05 ± 0.99 diopters (D) (range: -1.88 to +1.50 D). Mean cylinder was -0.70 ± 0.55 D (range: 0.00 to -2.25 D). Postoperative uncorrected distance visual acuity was 20/20 or better in 81% of eyes, for a population with corrected distance visual acuity (CDVA) of 20/20 or better in 95% before re-treatment. Mean postoperative SEQ relative to the target was +0.19 ± 0.49 D (range: -0.88 to +2.13 D), with 74% within ±0.50 D. Mean postoperative cylinder was -0.29 ± 0.24 D (range: 0.00 to -1.25 D). There was one line loss of CDVA in 15% of eyes, but no eyes lost two or more lines. There was a small increase in contrast sensitivity (P < .05). Overcorrection was identified in myopic re-treatments (n = 20) of -1.00 D or more; mean postoperative SEQ was +0.59 ± 0.64 D (range: -0.63 to +2.13 D).

CONCLUSIONS

Re-treatment after SMILE by LASIK achieved excellent visual and refractive outcomes, although these results indicate that myopic LASIK retreatment after primary myopic SMILE requires a different nomogram than for myopic LASIK re-treatment after primary myopic LASIK. [J Refract Surg. 2018;34(9):578-588.].

Inferior pseudo-hinge fulcrum technique and intraoperative complications of laser in situ keratomileusis retreatment after small-incision lenticule extraction

PURPOSE

To describe the evolution of a flap-lift technique for laser in situ keratomileusis (LASIK) retreatment after small-incision lenticule extraction (SMILE) and report the incidence of complications.

SETTING

London Vision Clinic, London, United Kingdom.

DESIGN

Retrospective case series.

METHODS

All retreatments between September 2013 and January 2017 were included. A bimanual inferior pseudo-hinge fulcrum flap-lift technique was developed to minimize the chance of tearing or entering the small incision. A flap lifter and a McPherson forceps were inserted into the inferior one third of the flap, slightly angled up to avoid perforating the small-incision lenticule extraction interface. One instrument provided countertraction, and the second separated the interface superiorly, keeping the tip away from the incision. One instrument was held against the hinge for the second instrument to separate the inferior one third. The incidence of intraoperative complications was analyzed.

RESULTS

The study evaluated 162 retreatments (4.12%) for 3933 small-incision lenticule extraction treatments (1-year maturity). The retreatment was LASIK (n = 135), side-cut only (n = 1), cap-to-flap procedure (CIRCLE) (n = 3), or photorefractive keratectomy (n = 23). Two eyes (1.4%) had a tear to the small incision. The small-incision lenticule extraction interface was accessed in 8 eyes (5.8%), 1 (0.7%) centrally, and the interface was lifted in 1 eye (0.7%). There were no complications in the last 84 consecutive procedures (60%) using the finalized technique.

CONCLUSION

The bimanual inferior pseudo-hinge fulcrum decreased the risk for accessing the small-incision lenticule extraction interface or tearing the small incision.

Small incision lenticule extraction (SMILE) techniques: patient selection and perspectives

Refractive lenticule extraction is becoming the procedure of choice for the management of myopia and myopic astigmatism owing to its precision, biomechanical stability, and better ocular surface. It has similar safety, efficacy, and predictability as femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and is associated with better patient satisfaction. The conventional technique of small incision lenticule extraction (SMILE) involves docking, femtosecond laser application, lenticule dissection from the surrounding stroma, and extraction. It has a steep learning curve compared to conventional flap-based corneal ablative procedures, and the surgical technique may be challenging especially for a novice surgeon. As SMILE is gaining worldwide acceptance among refractive surgeons, different modifications of the surgical technique have been described to ease the process of lenticule extraction and minimize complications. Good patient selection is essential to ensure optimal patient satisfaction, and novice surgeons should avoid cases with low myopia (thin refractive lenticules), difficult orbital anatomy, high astigmatism, or uncooperative, anxious patients to minimize complications. A comprehensive MEDLINE search was performed using “small incision lenticule extraction,” “SMILE,” and “refractive lenticule extraction” as keywords, and we herein review the patient selection for SMILE and various surgical techniques of SMILE with their pros and cons. With increasing surgeon experience, a standard technique is expected to evolve that may be performed in all types of cases with optimal outcomes and minimal adverse effects.

[SMILE (Small Incision Lenticule Extraction) among the corneal refractive surgeries in 2018 (French translation of the article)]

Refractive surgery is a field in constant evolution. In recent years, a new procedure has appeared under the name SMILE (Small Incision Lenticule Extraction). This technique, carried out solely with a femtosecond laser, should make it possible to better preserve corneal innervation and biomechanics. After a detailed review of the technique itself, we then focus on the scientific evidence for the safety and efficacy of SMILE and its current indications. Advantages of SMILE will be discussed in comparison to disadvantages of the conventional techniques, particularly concerning dry eye and the risk of corneal ectasia with LASIK. Lastly, the current limitations of SMILE (indications, retreatment) are discussed, and future applications are considered regarding improvements in the technique.

CIRCLE Enhancement After Myopic SMILE

PURPOSE

To report the outcomes of enhancement after small incision lenticule extraction (SMILE) using the VisuMax CIRCLE option (Carl Zeiss Meditec AG, Jena, Germany), which converts the SMILE cap into a femtosecond LASIK flap for secondary excimer laser application.

METHODS

Of 2,065 SMILE procedures, 22 eyes (1.1%) re-treated with CIRCLE with a follow-up of 3 months were included in the analysis. SMILE was performed in the usual manner. For re-treatment, the CIRCLE procedure was performed with pattern D flap creation on the VisuMax system and subsequent excimer laser ablation with a Zeiss MEL 90 laser (Carl Zeiss Meditec) with plano target in all cases.

RESULTS

Spherical equivalent was -5.56 ± 2.22 diopters (D) before SMILE and -0.51 ± 1.08 D before CIRCLE. CIRCLE enhancement was performed after a mean of 10.0 ± 7.9 months, allowed for safe flap lifting in all eyes, and resulted in a final manifest refraction spherical equivalent of 0.18 ± 0.31 D at 3 months (P < .008). The number of eyes within 0.50 and 1.00 D from target refraction increased from 31.8% to 90.9% and from 77.3% to 100%, respectively. Mean uncorrected distance visual acuity (UDVA) had already improved from 0.37 ± 0.16 to 0.08 ± 0.16 logMAR at 1 week (P < .0001), resulting in 0.03 ± 0.07 logMAR at 3 months (P < .0001). All eyes gained at least one line of UDVA. Corrected distance visual acuity (CDVA) remained unchanged at all time points (before vs after CIRCLE, P = .40). Two eyes (9.1 %) lost one line of CDVA; no eye lost two or more lines. The safety and efficacy indices were 1.03 and 0.97 at 3 months.

CONCLUSIONS

The CIRCLE procedure represents an effective re-treatment option after SMILE. Compared to surface ablation re-treatment after SMILE, CIRCLE seems to offer advantages in respect to speed of visual recovery, safety, and predictability, but at the price of flap creation. [J Refract Surg. 2018;34(5):304-309.].

Initial Single-Site Surgical Experience with SMILE: A Comparison of Results to FDA SMILE, and the Earliest and Latest Generation of LASIK

Introduction

The primary objective was to show our initial surgical single-site experience with small incision lenticule extraction (SMILE) after the official enrollment in March 2017 following Food and Drug Administration (FDA) approval for simple myopia in late 2016 in the United States and, subsequently, compare our results to the earliest and most advanced generation of excimer platforms for laser-assisted in situ keratomileusis (LASIK) surgery.

Methods

This was a retrospective single-site study of 68 eyes from 35 patients who had SMILE surgery. The patients’ preoperative and postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest sphere, manifest cylinder, intraoperative complications, and preoperative and postoperative visual symptoms were collected. We compared our findings to the results from the FDA SMILE study, and to the three earliest (1999–2000) and three of the most updated (2013–2016) platforms for LASIK.

Results

The cumulative UDVA was 20/20 and 20/40 or better in 74% and 100% of patients, respectively. The intended target refraction was within ± 0.5 and ± 1.00 D in 80% and 93% of cases, respectively. The prevalence of dry eyes decreased by nearly half from 1-week to the 6-month postoperative interval. Patients noted improvement in glare (17%), halos (17%), fluctuation (25%), and depth perception (8%) at the 6-month interval compared to preoperative levels.

Conclusions

This study’s findings are consistent with current SMILE reports. Notably, the results are superior to the earliest generation of LASIK, however inferior to the latest excimer platforms. SMILE does meet the efficacy and safety criteria met by FDA; however, there is a definite need for further improvement to reach the superior refractive outcomes produced by the latest generation of LASIK platforms.

SMILE (Small Incision Lenticule Extraction) among the corneal refractive surgeries in 2018

Refractive surgery is a field in constant evolution. In recent years, a new procedure has appeared under the name SMILE (SMall Incision Lenticule Extraction). This technique, carried out solely with a femtosecond laser, should make it possible to better preserve corneal innervation and biomechanics. After a detailed review of the technique itself, we then focus on the scientific evidence for the safety and efficacy of SMILE and its current indications. Advantages of SMILE will be discussed in comparison to the conventional techniques, particularly concerning dry eye and the risk of corneal ectasia related to LASIK. Lastly, the current limitations of SMILE (indications, retreatment) are discussed, and future applications are considered regarding new improvements in the technique.

A Modified Small-Incision Lenticule Intrastromal Keratoplasty (sLIKE) for the Correction of High Hyperopia: A Description of a New Surgical Technique and Comparison to Lenticule Intrastromal Keratoplasty (LIKE)

Patients with high hyperopia are generally confined to either spectacle wear or contact lenses as a primary means of refractive correction. For this patient population, the surgical corrective methods, such as hyperopic laser assisted in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) are imperfect options due to induction of higher-order aberrations, optical regression, and loss of best corrected distance visual acuity. Recently, there has been growing interest in lenticule implantation underneath a flap via lenticule intrastromal keratoplasty (LIKE) for high hyperopia correction (+3 diopters to +10 diopters). We instead propose a modified surgical technique (small-incision lenticule intrastromal keratoplasty, sLIKE), in which the lenticule is implanted inside an intrastromal pocket thereby causing less injury to the subbasal nerve plexus injury, less postoperative dry eye symptoms, less reduction in biomechanical strength, and lower chances for epithelial ingrowth. We provide an overview of these novel surgical techniques to treat high hyperopia, and compare the associated advantages and disadvantages. In addition, we will discuss the enhancement options and methods of optimization for both surgical techniques.

Retreatment strategies following Small Incision Lenticule Extraction (SMILE): In vivo tissue responses

With any refractive correction, including Small Incision Lenticule Extraction (SMILE), there may be a residual refractive error that requires a retreatment. Here, we investigated the tissue responses following various retreatment procedures in a rabbit model of SMILE. All rabbits underwent a -6.00D correction with SMILE. Two weeks later, they underwent -1.00D enhancement by: (i) VisuMax Circle, followed by excimer ablation (S+C); (ii) secondary SMILE anterior to the primary procedure (S+SE); or (iii) surface ablation (S+P), and were examined for 28 days. S+P induced corneal edema and haze, and more CD11b- (23±6 cells) and TUNEL-positive (36±4 cells) cells in the central stromal superficial layers early post-operatively (p<0.001 compared to other procedures). The corneas appeared normal on day 28 after S+P, but had a lower number of keratocytes near the laser ablated plane compared to other procedures. S+SE and S+C did not induce corneal haze and resulted similar level of fibronectin. However, S+C resulted in more inflammatory (10±2 cells; p = 0.001) and apoptotic cells (25±2 cells; p<0.001) compared to S+SE (7±1 inflammatory cells and 21±3 apoptotic cells) early post-operatively. In conclusion, each SMILE retreatment method resulted in unique tissue responses. S+SE offers advantages, such as minimal inflammation and cell death, as well as maintaining a ‘flap-less’ surgery, over other procedures. However, depending on the degree of enhancement, the lenticule may become too thin to be extracted and the procedure becomes more difficult to perform than S+C and S+P. S+P can maintain corneal integrity by avoiding flap creation and is technically more simple to perform than the others, but the surgery needs to be supplemented with mitomycin-C in order to reduce inflammation and modulate better wound healing.

Postoperative Efficacy, Predictability, Safety, and Visual Quality of Laser Corneal Refractive Surgery: A Network Meta-analysis

PURPOSE

To compare the postoperative efficacy, predictability, safety, and visual quality of all major forms of laser corneal refractive surgeries for correcting myopia.

DESIGN

Systematic review and network meta-analysis.

METHODS

Search of MEDLINE, EMBASE, Cochrane Library, and the US trial registry was conducted up to November 2015. Randomized controlled trials (RCT) reporting in accordance with the eligibility criteria were included in this review. We performed a Bayesian random-effects network meta-analysis.

RESULTS

Forty-eight RCTs were identified. For efficacy (uncorrected visual acuity [UCVA]), there were no statistically significant differences between any pair of treatments analyzed. The SUCRA (surface under the cumulative ranking curve) ranking (from best to worst) was femtosecond-based laser in situ keratomileusis (FS-LASIK), LASIK, small-incision lenticule extraction, femtosecond lenticule extraction (FLEx), photorefractive keratectomy (PRK), laser epithelial keratomileusis (LASEK), epipolis (Epi)-LASIK, transepithelial PRK (T-PRK). For predictability (refractive spherical equivalent [SE]), a statistically significant difference was found when FS-LASIK was compared with LASIK (odds ratio [OR] 2.29, 95% credible interval [CrI] 1.20-4.14), PRK (OR 2.16, 95% CrI 1.15-4.03), LASEK (OR 2.09, 95% CrI 1.08-4.55), and Epi-LASIK (OR 2.74, 95% CrI 1.11-6.20). The SUCRA ranking (from best to worst) was FS-LASIK, T-PRK, LASEK, PRK, LASIK, Epi-LASIK. There were no statistically significant differences in the safety (best spectacle-corrected visual acuity) comparisons. For both postoperative higher-order aberrations (HOAs) and contrast sensitivity (CS), there were no statistically significant differences between any pair of treatments analyzed. The SUCRA ranking results show that some corneal surface ablation techniques (PRK and LASEK) rank highest.

CONCLUSIONS

This network meta-analysis shows that there were no statistically significant differences in either visual outcomes (efficacy and safety) or visual quality (HOAs and CS). FS-LASIK behaved better in predictability than any other type of surgeries.

Enhancement after Small-Incision Lenticule Extraction: Incidence, Risk Factors, and Outcomes

PURPOSE

To report the incidence, risk factors, and outcomes of enhancement after small-incision lenticule extraction (SMILE).

DESIGN

Retrospective cohort study.

PARTICIPANTS

Five hundred twenty-four eyes of 307 patients who underwent SMILE at Singapore National Eye Center between February 2012 and March 2016.

METHODS

The data collected included patient age at primary SMILE, gender, race, preoperative and postoperative manifest refraction spherical equivalent (MRSE), preoperative and postoperative uncorrected distance visual acuity and corrected distance visual acuity, the occurrence of suction loss during the procedure, and the need for enhancement. All enhancements were carried out by performing an alcohol-assisted photorefractive keratectomy (PRK) procedure with application of mitomycin C (MMC).

MAIN OUTCOME MEASURES

Incidence, prevalence, preoperative and intraoperative risk factors for enhancement, and outcomes after enhancement.

RESULTS

The prevalence of enhancement was 2.7%, and 71.4% eyes had enhancement within 1 year of primary SMILE. The incidence of enhancement was 2.1% and 2.9% at 1 and 2 years, respectively. Age older than 35 years, preoperative MRSE more than -6.00 diopters (D), preoperative myopia more than 6.00 D, preoperative astigmatism more than 3.00 D, and intraoperative suction loss were significant risk factors for enhancement after SMILE after adjusting for all other covariates (odds ratios, 5.58, 4.80, 1.41, 3.06, and 2.14, respectively; P = 0.004, 0.021, 0.022, 0.002, and 0.020, respectively). In the patients who underwent bilateral SMILE, the first-operated eye had a marginal trend toward significance for enhancement (P = 0.054). There was no gender or racial difference. In the 14 eyes requiring enhancement, the uncorrected distance visual acuity before enhancement ranged from 20/80 to 20/25, and the mean attempted enhancement spherical equivalent was -0.50±0.86 D. The uncorrected distance visual acuity improved in most patients (92.9%) after enhancement.

CONCLUSIONS

The 2-year incidence of enhancement after SMILE was 2.9%. Risk factors associated with enhancement included older age at SMILE procedure, greater preoperative MRSE, greater preoperative myopia, greater preoperative astigmatism, and the occurrence of intraoperative suction loss. Clinical outcomes of using PRK with application of MMC for enhancement were good.

Corneal biomechanics after small-incision lenticule extraction versus Q-value-guided femtosecond laser-assisted in situ keratomileusis

Purpose

The aim of this study was to compare the changes in corneal biomechanical properties following small-incision lenticule extraction (SMILE) versus Q-value–guided femtosecond laser-assisted in situ keratomileusis (Q-FS-LASIK).

Methods

In this prospective comparative study, patients with a sphere plus cylinder measurement of less than −10.00 D and cylinder measurement of less than −5.00 D were included in the study. A total of 160 patients (160 eyes) with myopia and myopic astigmatism were divided into the two groups, with 80 patients (80 eyes) allocated to SMILE and 80 patients (80 eyes) allocated to Q-FS-LASIK. Corneal hysteresis (CH) and the corneal resistance factor (CRF) were quantitatively assessed using the Ocular Response Analyzer (ORA) preoperatively and at 1 day, 2 weeks, and 1 and 3 months postoperatively.

Results

Both types of surgery were associated with statistically significant decreases in CH and the CRF at postoperative day 1 (both P < 0.01). In both groups, the decreases subsequently stabilized with no further deteriorations compared to postoperative day 1 (P > 0.05). Both groups showed similar biomechanical changes at each time point (all P > 0.05).

Conclusions

Both SMILE and Q-FS-LASIK resulted in a decrease in CH and the CRF at postoperative 1 day, with the decreases stabilizing after this point. There were no significant differences between the short term effects of SMILE and Q-FS-LASIK on corneal biomechanical properties.