Four-year observation of predictability and stability of small incision lenticule extraction

Ten-year outcomes following small incision lenticule extraction for up to -10Dioptres myopia

CLINICAL RELEVANCE

More than 6 million small-incision lenticule extraction (SMILE) procedures have been performed worldwide since 2011. Therefore, its long-term safety and efficacy should be investigated.

BACKGROUND

This study aimed to evaluate 10-year refractive outcomes, corneal stability, axial length, and wavefront aberrations in patients who underwent SMILE to correct myopia.

METHODS

Thirty two patients (32 eyes) who underwent SMILE-based myopic correction. Corrected distance visual acuity, uncorrected distance visual acuity, corneal stability, axial length, and wavefront aberrations were evaluated preoperatively and at 1 month and 1, 5, and 10 years postoperatively.

RESULTS

At 10 years postoperatively, the safety and efficacy indices for the patients included in this study were 1.19 ± 0.21 and 1.04 ± 0.27, respectively. For 26 (81%) and 30 eyes (94%), correction to within ±0.50 D and ±1.00 D of the target was achieved, respectively. Over the 10-year follow-up duration, a mean -0.32 ± 0.56 D regression was observed (-0.03 ± 0.06 D/year). Relative to baseline, horizontal and vertical comas significantly increased, as did the incidence of higher-order aberrations (all P < 0.001), whereas axial length and corneal elevation remained stable during follow-up.

CONCLUSION

These results indicate that the SMILE-based correction for myopia of up to -10 Dioptres is safe, effective, and stable, with relatively constant wavefront aberrations and corneal stability over time after treatment.

Comparison of visual quality after SMILE correction of low-to-moderate myopia in different optical zones

OBJECTIVE

To compare the effects of different optical zones for small-incision lenticule extraction (SMILE) on postoperative visual quality in low-to-moderate myopia.

METHODS

This retrospective case-control study involved patients who underwent SMILE using two optical-zone diameters: 6.5 mm (50 patients, 100 eyes) and 6.8 mm (50 patients, 100 eyes). Uncorrected visual acuity (UCVA), best corrected visual acuity, spherical equivalent (SE), corneal higher-order aberrations (HOAs), and subjective visual-quality questionnaire scores were assessed.

RESULTS

Postoperatively, UCVA and SE did not differ between the two groups (P > 0.05). In both groups, corneal HOAs, spherical aberration, and coma significantly increased at 1 and 3 months postoperatively (P < 0.05), while trefoil was unchanged after surgery (P > 0.05). Corneal HOAs, spherical aberration, and coma significantly differed between the groups at 1 and 3 months (P < 0.05), while trefoil did not (P > 0.05). Visual-quality scores were higher in the 6.8 mm group than in the 6.5 mm group at 1 month (P = 0.058), but not at 3 months (P > 0.05). In both groups, subjective scores significantly decreased at 1 month (P < 0.05) and gradually returned to the preoperative level at 3 months (P > 0.05). The subjective visual-quality scores were negatively and positively correlated with pupillary and optical-zone diameter, respectively (P < 0.05 for both). Objective visual-quality indicators (HOAs, spherical aberration, and coma) were negatively correlated with optical-zone diameter (P < 0.05) but not pupillary diameter (P > 0.05).

CONCLUSION

SMILE in different optical zones effectively corrected low-to-moderate myopia. The larger the optical-zone diameter, the better the early postoperative visual quality.

TFOS Lifestyle: Impact of elective medications and procedures on the ocular surface

The word "elective" refers to medications and procedures undertaken by choice or with a lower grade of prioritization. Patients usually use elective medications or undergo elective procedures to treat pathologic conditions or for cosmetic enhancement, impacting their lifestyle positively and, thus, improving their quality of life. However, those interventions can affect the homeostasis of the tear film and ocular surface. Consequently, they generate signs and symptoms that could impair the patient's quality of life. This report describes the impact of elective topical and systemic medications and procedures on the ocular surface and the underlying mechanisms. Moreover, elective procedures performed for ocular diseases, cosmetic enhancement, and non-ophthalmic interventions, such as radiotherapy and bariatric surgery, are discussed. The report also evaluates significant anatomical and biological consequences of non-urgent interventions to the ocular surface, such as neuropathic and neurotrophic keratopathies. Besides that, it provides an overview of the prophylaxis and management of pathological conditions resulting from the studied interventions and suggests areas for future research. The report also contains a systematic review investigating the quality of life among people who have undergone small incision lenticule extraction (SMILE). Overall, SMILE refractive surgery seems to cause more vision disturbances than LASIK in the first month post-surgery, but less dry eye symptoms in long-term follow up.

Influence of optical zone on myopic correction in small incision lenticule extraction: a short-term study

BACKGROUND

To evaluate the influence of preoperative optical zone on myopic correction in small incision lenticule extraction.

METHODS

In this retrospective clinical study, 581 eyes from 316 patients underwent SMILE were selected, including 117 eyes in the small optical zone group (range from 6.0 to 6.4 mm) and 464 eyes in the large optical zone group (range from 6.5 to 6.8 mm). The measurements included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical, and cylinder were measured preoperatively and 3 months postoperatively. Propensity score match (PSM) analysis was performed with age, gender, eye (right/left), keratometry and preoperative spherical equivalent between two different groups. The influence of optical zones on postoperative refractive outcomes were evaluated using univariate regression analysis.

RESULTS

In total, 78 pairs of eyes were selected by PSM (match ratio 1:1). There were no differences in the age, gender, eye (right/left), keratometry or preoperative spherical equivalent between the small and large optical zone groups. However, the difference of postoperative spherical equivalent was significantly between groups. Patients with larger optical zones had a trend towards less undercorrection (P = 0.018). Univariate linear regression model analysis found that each millimeter larger optical zone resulted in 8.13% or 0.39D less undercorrection (P < 0.001). The dependency between the optical zones and postoperative spherical equivalent was significant in the higher preoperative myopia group (r = 0.281, P < 0.001), but not significant in the lower myopia group (r = 0.028, P = 0.702).

CONCLUSION

The diameter of optical zones would affect postoperative refractive outcomes in small incision lenticule extraction. This study indicated that larger optical zones induced less undercorrection, especially in patients with high myopia.

Twelve-year global publications on small incision lenticule extraction: A bibliometric analysis

Purpose

To analyze the development process of small incision lenticule extraction (SMILE) surgery in a 12-year period.

Methods

We conducted a literature search for SMILE research from 2011 to 2022 using the Science Citation Index Expanded (SCIE) of the Web of Science Core Collection (WoSCC). The VOS viewer, and CiteSpace software were used to perform the bibliometric analysis. Publication language, annual growth trend, countries/regions and institutions, journals, keywords, references, and citation bursts were analyzed.

Results

A total of 731 publications from 2011 to 2022 were retrieved. Annual publication records grew from two to more than 100 during this period. China had the highest number of publications (n = 326). Sixty-five keywords that appeared more than four times were classified into six clusters: femtosecond laser technology, dry eye, biomechanics, visual quality, complications, and hyperopia.

Conclusion

The number of literatures has been growing rapidly in the past 12 years. Our study provides a deep insight into publications on SMILE for researchers and clinicians with bibliometric analysis for the first time.

Long-term efficacy and safety profiles following small incision lenticule extraction in eyes with ≥ 5-year follow-up

PURPOSE

To evaluate long-term efficacy, safety, predictability and stability (refractive and keratometric) of myopic and myopic astigmatism correction with Small Incision Lenticule Extraction (SMILE).

METHODS

Single center retrospective review of eyes undergoing SMILE from 2012-2015. Forty-two eyes (23 patients) with ≥ 5-year follow-up. Variables analyzed were preoperative, 3-month, 1-year and last follow-up uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, spherical equivalent (SE) and mean keratometry. Descriptive statistics were performed and results reported following the Standard for Reporting Astigmatism Outcomes.

RESULTS

Mean follow-up of 5.98 ± 0.90 years. Mean preoperative SE was -5.26 ± 1.22D (range -2.50 to -8.12D). Mean preoperative cylinder was -0.66 ± 0.61D (range 0.00 to -2.25D). Efficacy and safety indices were 0.86 and 0.98, respectively. In total, 81% of operated eyes achieved an UDVA of ≥ 0.09 logMar (20/25 Snellen). At the last follow-up, ≥1 line of CDVA was gained in 14% of eyes. Five percent lost 1 line of CDVA, and no eye loss ≥2 lines of CDVA. Sixty-nine percent of eyes were within ± 0.50D and 86% within ± 1.00D of the attempted SE correction. Ninety-one percent of eyes had ≤0.50D of postoperative astigmatism and 71% were within ± 15° from the intended correction axis. At the final follow-up, a statistically significant myopic regression of 0.19 ± 0.50D was observed (p = 0.01).

CONCLUSIONS

Long-term results demonstrate that SMILE is effective, predictable and safe. SMILE has good stability, low regression compared to LASIK, and no signs of corneal ectasia staging within our standard criteria.

One year outcomes after small incision lenticule extraction ReLEX in the correction of myopia and myopic astigmatism

Purpose

To report the visual and refractive outcomes of small incision lenticule extraction ReLEX (SMILE) technique using VisuMax femtosecond laser in myopia and myopic astigmatism patients.

Material and methods

A non-randomized clinical study has been conducted on patients with myopia and myopic astigmatism who underwent ReLEX SMILE technique, using the Zeiss VisuMax Laser system (Carl Zeiss Meditec AG, Jena, Germany) at Oculens Clinic, Cluj-Napoca, Romania. Patients older than 18 years, with ocular astigmatism up to -5 diopters (D), spherical equivalent up to -10.00 D, corrected distance visual acuity (CDVA) of 0.3 or better before the surgery, stable refraction for one year, and with a minimum calculated post operator residual stromal bed of 250μ were included in the study.

Results

The study involved a total of 25 myopic eyes (median of sphere diopters equal with -4D) and 67 myopic astigmatic eyes (median of cylinder diopters equal with -1.5 D). The mean refractive spherical equivalent (MRSE) on patients with myopic eyes reduced from -4.25D (median) to -0.5D at one month follow-up, -0.25 D at 6 and 12 months. The mean refractive spherical equivalent (MRSE) on patients with astigmatic myopic eyes reduced from-6.25 D to -0.67 D at one month, -0.62 D at six and twelve months. The value of sphere decreased postoperatively on myopic eyes with a median of -0.25D at one, six and twelve months. The value of cylinder decreased postoperatively on myopic astigmatic eyes with a median of -0.50 D at one month, -0.25 D at six months and -0.50 D at 12 months. At 6 and 12 months, 20 (80.0%) of myopic eyes were maintained within ±0.5 D and 22 (88.0%) with ±1D. On both groups (myopic eyes and myopic astigmatic eyes), statistically significant differences were observed when the keratometric baseline values were compared to each follow-up (P-values < 0.0001), without any significant differences between follow-ups (P-values>0.15). At 1-month follow-up, uncorrected distance visual acuity (UDVA) was better than or equal to 0.5 in 88.0% of myopic eyes and 82.1% of myopic astigmatic eyes. UDVA remained stable in all cases of myopic eyes at six months and the percentage increased at 92.0% in myopic eyes. UDVA slightly increased at 6-months (85.1%) and remained at the same value at 12-months in myopic astigmatism eyes.

Conclusions

SMILE proved an effective and safe refractive corneal procedure and provided a predictable and stable correction of myopia and myopic astigmatism. SMILE technique demonstrated very good outcomes in terms of keratometric, cylinder, spherical measurements.

Comparison of small incision lenticule extraction and transepithelial photorefractive keratectomy in terms of visual quality in myopia patients

PURPOSE

To comprehensively compare visual quality between small incision lenticule extraction (SMILE) and transepithelial photorefractive keratectomy (tPRK).

METHODS

Sixty-four eyes in the SMILE group and 42 eyes in the tPRK group were enrolled in this study. In both groups, visual acuity, manifest refraction, higher-order aberrations (HOAs), contrast sensitivity (CS) at four spatial frequencies (3, 6, 12, 18 c/d) under three conditions (photopic, low glare, high glare), the cut-off value of the modulation transfer function (MTFcut-off), the objective scatter index (OSI) and the Strehl ratio (SR) were measured preoperatively and 1, 3 and 6 months postoperatively.

RESULTS

At 6 months postoperatively, the SMILE and tPRK groups showed similar safety, efficacy and predictability. Additionally, MTFcut-off, SR and OSI exhibited comparable results. In contrast, the photopic area under the logarithm of the CS function (AULCSF) showed better outcomes in the tPRK group than in the SMILE group (SMILE versus tPRK: 1.21 ± 0.10 versus 1.25 ± 0.09, p = 0.014). Furthermore, the induced coma aberrations were larger in the SMILE group (SMILE versus tPRK: 0.10 ± 0.16 versus 0.06 ± 0.12, 95% CI [0.08, 0.31], p < 0.0001).

CONCLUSIONS

Both SMILE and tPRK obtained comparable visual quality at 6 months postoperatively, accompanied by better photopic CS and smaller induced coma aberrations with tPRK. Paying more attention to alignment or developing a centration technique would be beneficial for visual quality when performing SMILE.

Vision-related quality of life with myopia management: A review

The disease of myopia has come into focus as a worldwide public health concern. Myopia has shown increasing prevalence, incidence at earlier age and progression to a higher degree. Progressive increase in degree of myopia is strongly associated with increase in axial length of the eye. Various interventions have been shown to slow axial elongation in children. These interventions have been studied to assess efficacy in slowing axial elongation and correction of vision. In addition, research into quality of vision, risk of adverse events, overall safety and impact on vision-related quality (VR-QoL) of life has been pursued. In contrast, studies have been published to demonstrate the risks of myopia, high myopia and increased axial length. This review will discuss VR-QoL assessment on the most effective and most commonly prescribed interventions to slow axial elongation and myopia progression. The patient attributes considered are VR-QoL scores from validated instruments. The development and use of validated survey instruments to assess the patient-reported outcomes is discussed. The review demonstrates that there are numerous factors that may impact VR-QoL to evaluate in the decision-making process when eye care providers consider when, how and if to prescribe myopia management (MM) for children with myopia.

Refractive results with SMILE using lower energy settings in the United States

Purpose

To report the visual and refractive results of small incision lenticule extraction (SMILE) with low energy settings in the United States (US) and to evaluate outcomes for low astigmatism treatment.

Setting

Private clinical practice.

Design

Retrospective cohort study.

Methods

This study retrospectively reviewed 462 consecutive eyes that underwent SMILE with lower energy settings. Inclusion criteria included all patients between the ages of 19–39 with myopic astigmatism up to -11.25 diopters (D) spherical equivalent (sphere up to -10.00 D, astigmatism up to -3.00 D), and corrected distance visual acuity of at least 20/25. Eyes with low astigmatism (0.25 D-0.50 D) were also included. Outcome analysis was performed according to the Standard Graphs for Reporting Refractive Surgery at postoperative month (POM) 1, and POM 3–6 when data were available.

Results

The mean preoperative spherical equivalent treated was -4.96 ± 2.07; at POM 1, 92% of eyes achieved uncorrected visual acuity (UCVA) of 20/20 or better and maintained visual stability throughout the remainder of the study. At last visit, 431 eyes (93%) achieved UCVA of 20/20 or better, and 461 eyes (99.8%) were 20/25 or better. Ninety-seven (21%) eyes gained at least 1 Snellen line of corrected distance visual acuity and no eyes lost 2 or more lines. Almost all eyes (n = 453, 98%) were within 0.5D of target; 85% of eyes with low astigmatism had ≤0.25 D at last visit compared to 80% of eyes with moderate astigmatism.

Conclusions

SMILE with U.S.-approved low energy settings is safe, predictable, and efficacious and provides patients with a fast visual recovery.

7-Year Results of SMILE for High Myopia: Visual and Refractive Outcomes and Aberrations

PURPOSE

To evaluate the 7-year visual, refractive, and optical outcomes following small incision lenticule extraction (SMILE) for high myopia and myopic astigmatism.

METHODS

Sixty-nine eyes (69 patients) undergoing SMILE between March 2011 and January 2012 at Aarhus University Hospital were included. Preoperative, 3-month, 3-year, and 7-year evaluation included: manifest refraction and uncorrected (UDVA) and corrected (CDVA) distance visual acuities, total corneal refractive power (TCRP), average keratometry (Km), aberrations, and central corneal thickness (CCT).

RESULTS

Preoperative spherical equivalent averaged -7.53 ± 1.18 diopters (D). Twenty-seven eyes were targeted emmetropia. In the emmetropic eyes, the postoperative logMAR UDVA remained stable (P = .11). When including all eyes, UDVA became worse from 3 to 7 years (3 months: 0.050 ± 0.16 logMAR; 3 years: 0.044 ± 0.21 logMAR; 7 years: 0.131 ± 0.29 logMAR; P < .027), whereas CDVA remained stable (3 months: -0.07 ± 0.09 logMAR; 3 years: -0.09 ± 0.08 logMAR; 7 years: -0.09 ± 0.08 logMAR, P > .99). At 7 years, 59.4% and 81.2% were within ±0.50 and ±1.00 D of target refraction, respectively. Average refractive regression was significant from 3 months to 7 years (-0.34 ± 0.69 D) and from 3 to 7 years (-0.25 ± 0.41 D, P < .05). After exclusion of three outliers with high myopic correction (< 9.63 D) and considerable regression (<-1.50 D), the average regression over 7 years was -0.25 ± 0.49 D (P = .004) with no significant change from 3 to 7 years (P = .069). Average CCT, TCRP, and anterior Km significantly increased (P < .001), whereas the posterior Km and total corneal aberrations remained stable (P > .092).

CONCLUSIONS

The long-term visual outcome remained stable after SMILE, but with an average regression of -0.34 D over 7 years. A minor group with high myopic correction exhibited considerable refractive regression years after SMILE. [J Refract Surg. 2021;37(10):654-661.].

Reliability and Validity of the Persian Version of Quality of Life Impact of Refractive Correction Questionnaire

PURPOSE

To evaluate the psychometric properties of the Persian version of quality of life impact of refractive correction (QIRC) questionnaire and its utility in assessment of refractive error-related quality of life (QoL) following photorefractive keratectomy (PRK).

METHODS

Patients with low-to-moderate myopia (-0.75 to - 6.0) were enrolled in this study. Standard alcohol-assisted PRK was performed in all patients. The QIRC questionnaire was translated into a Persian version using the standard method. Patients completed QIRC questionnaire preoperatively and 3-month postoperatively. A group of patients completed the questionnaire twice preoperatively. Psychometric properties were evaluated by internal consistency (Cronbach's α), item-total correlation, and known group construct validity. Intraclass correlation coefficient (ICC) were used to examine the repeatability.

RESULTS

One hundred forty-seven patients (60 males and 87 females) with a mean age of 26.3 ± 5.5 (range, 18-39) years were enrolled. Cronbach's α for total score was 0.923. Item-total correlation was above 0.3 for all items. ICC was 0.978 for total score. Preoperatively, predominantly contact lens wearers showed significantly better total QIRC score than predominantly spectacle wearers (P = 0.017), which showed good known group validity. Total QIRC score significantly increased from 41.31 ± 6.69 preoperatively to 50.47 ± 7.26 postoperatively (P < 0.0001). Improvement in total QIRC score was observed both in contact lens wearers and spectacle wearers.

CONCLUSION

The Persian version of QIRC questionnaire is a valid and reliable tool. Refractive error-related QoL assess by QIRC was significantly improved after PRK in an Iranian population.

Five-year results of refractive outcomes and vision-related quality of life after SMILE for the correction of high myopia

AIM

To evaluate the long-term visual, refractive outcomes and vision-related quality of life after small incision lenticule extraction (SMILE) for the correction of high myopia.

METHODS

Thirty patients (60 eyes) with high myopia who underwent SMILE more than 5y were selected as the SMILE group. Another 30 high myopia patients (60 eyes) who had worn corrective spectacles for more than 5y were selected as the control group. In SMILE group, the postoperative follow-up time were 3, 6mo, 1 and 5y. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SE), and ocular axial length (AL) were analyzed. The Chinese version of the National Eye Institute Visual Function Questionnaire-25 (CHI-NEI-VFQ-25) was used to evaluate the vision-related quality of life in the SMILE group and the control group.

RESULTS

In SMILE group, the mean preoperative SE was -7.29±0.87 D (range -6.00 to -9.125 D). At 5-year follow up, the efficacy index and safety index of SMILE were 1.09±0.18 and 1.19±0.12, respectively. Five years postoperatively, 44 eyes (73%) obtained a visual acuity of 20/20 or better. There were no eyes with CDVA loss of one or more Snellen lines. Forty-nine eyes (82%) and 57 eyes (95%) were within ±0.50 and ±1.00 D of attempted correction at 5-year follow-up, respectively. Forty-eight eyes (80%) had astigmatism <0.50 D at 5-year follow-up. The postoperative mean SE values at 3, 6mo, 1, and 5y were 0.11±0.44, 0.07±0.45, -0.02±0.41, and -0.15±0.46 D, respectively. No significant change was observed in the ocular AL from before operation to 5y postoperatively (26.08±0.96 mm vs 26.01±0.94 mm, P=0.068). Compared to the control group, the SMILE group showed a significantly higher total score on the CHI-NEI-VFQ-25 (90.14 vs 81.43, P<0.001).

CONCLUSION

In the present study, in a long-term follow-up we demonstrate that correcting high myopia with SMILE is safe, effective, and predictable. Vision-related quality of life after SMILE is better in the SMILE group than in the control group who wore corrective spectacles.

Effect of SMILE-derived decellularized lenticules as an adhesion barrier in a rabbit model of glaucoma filtration surgery

Background

To investigate the effects of small incision lenticule extraction (SMILE)-derived decellularized lenticules on intraocular pressure (IOP) and conjunctival scarring in a rabbit model of glaucoma filtration surgery.

Methods

Trabeculectomy was performed on both eyes of New Zealand rabbits. A decellularized lenticule was placed in the subconjunctival space in one eye of the rabbits (the decellularized lenticule group), and no adjunctive treatment was performed in the fellow eye (the control group). The filtering bleb features and IOP were evaluated 0, 3, 7, 14, 21, and 28 days after surgery, and histopathologic examination was performed 28 days after surgery.

Results

Decellularized lenticules significantly increased bleb survival and decreased IOP postoperatively in the rabbit model with no adverse side effects. The histopathologic results showed a larger subconjunctival space and less subconjunctival fibrosis in the decellularized lenticule group.

Conclusions

Decellularized lenticules can prevent postoperative conjunctiva-sclera adhesion and fibrosis, and they may represent a novel antifibrotic agent for trabeculectomy.

Comparison of the optical quality after SMILE and FS-LASIK for high myopia by OQAS and iTrace analyzer: a one-year retrospective study

BACKGROUND

To compare the correction effect and optical quality after small-incision lenticule extraction (SMILE) and femtosecond laser assisted laser in situ keratomileusis (FS-LASIK) for high myopia.

METHODS

51 high myopia eyes after SMILE and 49 high myopia eyes after FS-LASIK were enrolled and divided into two groups retrospectively. The OQAS and iTrace analyzer were used for optical quality inspection. Between the two groups the spherical equivalent (SE), astigmatism, uncorrected distant visual acuity (UDVA), strehl ratio (SR), modulation transfer function cutoff frequency (MTF cutoff), objective scatter index (OSI) and wavefront aberrations were analyzed and compared before surgery and at 1, 6 and 12 months after surgery.

RESULTS

After the operation: (1) SE and astigmatism declined and UDVA increased significantly in both groups, and UDVA was better after SMILE than FS-LASIK. (2) SR and MTF cutoff reduced and OSI increased significantly after SMILE and FS-LASIK. SR and MTF cutoff were significantly higher after SMILE than FS-LASIK. OSI was significantly lower after SMILE than FS-LASIK. (3) The total wavefront aberration, total low-order wavefront aberration, defocus and astigmatism aberration as well as trefoil aberration reduced significantly in both groups. The total high-order wavefront aberration increased significantly after FS-LASIK. The spherical and coma aberration increased significantly in both groups. The total high-order wavefront aberration and coma aberration at 1 month were higher after FS-LASIK than SMILE.

CONCLUSION

The optical quality descended after SMILE and FS-LASIK. SMILE was superior to FS-LASIK at the correction effect and optical quality for high myopia. The combination of OQAS and iTrace analyzer is a valuable complementary measurement in evaluating the optical quality after the refractive surgery.

TRIAL REGISTRATION

This is a retrospective study. This research was approved by the ethics committee of Xiangya Hospital and the IRB approval number is 201612074.

Effect of Wavefront Aberrations on Night Vision Problems and Mesopic Contrast Threshold After SMILE

PURPOSE

To investigate the effect of wavefront aberrations on night vision problems and mesopic contrast threshold after small incision lenticule extraction (SMILE).

METHODS

Forty-two participants (84 eyes) who underwent SMILE were included in this prospective observational study. Visual outcomes including uncorrected distance visual acuity (UDVA), subjective manifest refraction, mesopic contrast threshold (Binoptometer 4P; Oculus Optikgeräte GmbH), and higher order aberrations (HOAs) were analyzed before and 3 months after surgery. The patient's night vision satisfaction was assessed using a questionnaire.

RESULTS

The mean spherical equivalent was -5.30 ± 1.38 diopters (D) preoperatively and -0.06 ± 0.15 D postoperatively. UDVA was better than 20/20 in 98.81% of the patients and better than 20/25 in all patients. Scores of night vision satisfaction and glare changed significantly in the postoperative period (F = 8.463, P = .001; F = 69.518, P < .001, respectively). Preoperative spherical diopters (lower order aberrations) were positively correlated with night vision satisfaction (r = -0.329, P = .041) and glare score (r =-0.332, P = .039). Age (odds ratio [OR] = 1.272, 95% CI = 1.019 to 1.589) and preoperative spherical diopter (OR = 0.437, 95% CI = 0.199 to 0.975) were correlated with night vision satisfaction scores by analysis of binary regression. The root mean square value of total HOAs increased 3 months after surgery (t = -6.873, P < .001) with an increase in horizontal coma (Z₃¹) and spherical aberration (Z₄⁰) (P < .001). No correlation was observed between glare score and HOAs; however, patients with higher preoperative myopia demonstrated continuously decreasing contrast under mesopic conditions and higher postoperative horizontal coma.

CONCLUSIONS

Myopic patients with higher preoperative spherical errors experienced more glare at night after SMILE surgery. Postoperative horizontal coma was associated with worse mesopic contrast thresholds. [J Refract Surg. 2021;37(7):446-452.].

Small incision lenticule extraction retreatment in a patient with high residual refractive error after photorefractive keratectomy: A case report

A 36-year-old male underwent uneventful small incision lenticule extraction (SMILE) for the correction of his high residual refractive error 12 years after photorefractive keratectomy (PRK). Preoperatively, uncorrected distance visual acuity (UDVA) was counting fingers in both eyes. Corrected distance visual acuity was 20/20 in the right and 20/30 in the left eye due to amblyopia. One month after SMILE, UDVA was 20/20 and 20/30 in the right and left eye, respectively; post-PRK corneal haze had reduced. During the 4-year follow-up, UDVA remained stable and there were no complications. SMILE could be a good alternative approach for retreatment in post-PRK patient.

Influence of Preoperative Keratometry on Refractive Outcomes for Myopia Correction With Small Incision Lenticule Extraction

PURPOSE

To evaluate the effect of preoperative keratometry on refractive outcomes after small incision lenticule extraction (SMILE) for myopia.

METHODS

This retrospective study comprised 515 consecutive eyes that had SMILE to correct myopia. Pearson correlation and linear regression were used to determine the relationship between residual spherical equivalent and preoperative keratometry. The same analyses were repeated in the quartiles with the lowest and highest preoperative myopia.

RESULTS

Preoperatively, the mean spherical equivalent was -5.67 ± 1.87 diopters (D) (range: -1.63 to -9.75 D) and the mean keratometry was 43.10 ± 1.30 D (range: 38.90 to 47.00 D). Three months postoperatively, the mean spherical equivalent was -0.07 ± 0.18 D. After adjustment for age, sex, and preoperative spherical equivalent, greater postoperative undercorrection occurred in eyes with steeper corneas (P = .001). Each diopter of steeper keratometry resulted in 0.52% (0.03 D) more undercorrection. Correlation between the mean preoperative keratometry and residual spherical equivalent was significant in the lower preoperative myopia group (r = -0.24, P = .006), but not significant in the higher myopia group (r = -0.02, P = .809).

CONCLUSIONS

Preoperative keratometry affects refractive outcomes after SMILE. Steeper corneas have greater undercorrection, especially in eyes with low myopia. Knowledge of the correlation between refractive outcomes of SMILE and keratometry would help in modifying current treatment algorithms. [J Refract Surg. 2020;36(6):374-379.].

Transient effect of suction on the retinal neurovasculature in myopic patients after small-incision lenticule extraction

PURPOSE

To characterize retinal neurovasculature changes after small-incision lenticule extraction (SMILE) in myopic patients.

SETTING

Ophthalmic Center, the Second Affiliated Hospital of Guangzhou Medical University, China.

DESIGN

Prospective interventional study.

METHODS

The corrected distance visual acuity/uncorrected distance visual acuity, corrected intraocular pressure (CIOP), and corneal tomography were evaluated at baseline (PRE), postoperative day (POD) 1, and POD 7. Ganglion cell-inner plexiform layer (GCIPL) and peripapillary retinal nerve fiber layer (pRNFL) thicknesses were measured. The vessel area densities (VADs, %), vessel skeleton densities (VSDs, %), vessel diameter index (VDI), and fractal dimensions (Dbox) of the superficial vascular plexus (SVP) and deep vascular plexus (DVP) were measured in a circular area (ϕ 2.5 mm) centered on the fovea.

RESULTS

A total of 38 myopic patients were recruited. The GCIPL thickness was increased after SMILE at POD 1 and POD 7 (P < .01) but no significant changes in the pRNFL thickness. The VAD, VSD, and Dbox of the SVP were decreased at POD 1 (P < .01), but not at POD 7. The VDI in small vessels of the SVP and DVP was decreased at POD 1 (P < .05) and increased at POD 7 (P < .05). Changes in CIOP were positively correlated with changes in the GCIPL thickness. Changes in CIOP were negatively correlated with changes in the VAD of small vessels and the Dbox of total vessels in the DVP. Changes in CIOP were negatively correlated with the VSD and VDI of small vessels in the DVP and changes in the VDI of big vessels in the SVP.

CONCLUSIONS

The transient fluctuations in the retinal neurovasculature after SMILE may represent a characteristic homeostasis pattern in patients after refractive surgery.

Functional Optical Zone and Visual Quality After Small-Incision Lenticule Extraction for High Myopic Astigmatism

Introduction

The aim of this study was to compare the functional optical zone (FOZ) after correction of high myopic astigmatism and low myopic astigmatism by small-incision lenticule extraction (SMILE).

Methods

In this prospective study, 30 patients who received SMILE for high myopic astigmatism correction (cylinderical diopters ≤ − 2.0D) were enrolled in the high astigmatism group (HA). The control group comprised 40 patients who underwent SMILE for low myopic astigmatism correction (LA; cylinderical diopters ≥ − 0.5D). FOZ was delineated as the area outlined by a change of 0.5D relative to the power at the corneal vertex on the total corneal refractive power map. An ellipse-fitting program (MatLab) was used to calculate some parameters of the FOZ. Visual quality evaluations were also conducted, including evaluations of wavefront aberrations, optical quality, and intraocular scattering, and completion of a quality of life questionnaire. All of the right eyes were analyzed in the study.

Results

The preoperative average treatment spherical equivalent (− 5.77 ± 1.86D vs. − 6.49 ± 1.49D; P = 0.074), lenticule thickness (120.87 ± 23.27 μm vs. 118.53 ± 21.66 μm; P = 0.666), and programmed optical zone (6.58 ± 0.17 mm vs. 6.65 ± 0.18 mm; P = 0.104) were comparable between the HA and LA groups. The long axes (6.99 ± 1.14 mm vs. 5.32 ± 0.61 mm; P < 0.001), short axes (4.66 ± 0.96 mm vs. 4.23 ± 0.64 mm; P = 0.047), and area (25.90 ± 8.03 mm² vs. 17.92 ± 4.36 mm²; P < 0.001) of the FOZ were significantly larger in the HA group than in the LA group. The centration of the FOZ were comparable between the two groups (0.62 ± 0.25 mm vs. 0.70 ± 0.25 mm; P = 0.194). Postoperative spherical aberration was lower in the HA group than in the LA group (0.07 ± 0.05 μm vs. 0.14 ± 0.10 μm; P = 0.001). There was no significant difference in the ocular scatter index (0.80 ± 0.46 vs. 0.73 ± 0.46; P = 0.447), modulated transfer function (MTF)_cutoff (37.89 ± 9.79 cpd vs. 39.78 ± 7.45 cpd; P = 0.363), and Strehl in two dimensions (Strehl2D) ratio (0.20 ± 0.04 vs. 0.20 ± 0.04; P = 0.363) between the HA group and the LA group. There were no significant differences in the scores on quality of life between the HA and LA groups (45.88 ± 2.15 vs. 45.64 ± 1.84; P = 0.423). Correlation analysis revealed that increase in the spherical aberration was significantly correlated with the long axes, short axes and area in the FOZ in both groups.

Conclusion

With a comparable optical design and attempted correction in SMILE, the eyes with higher myopic astigmatism correction achieved larger FOZ than the eyes with lower myopic astigmatism correction. Consequently, less spherical aberration induction was created after higher myopic astigmatism correction. This result may be associated with less corneal volume sculpted by laser for the higher astigmatism treatment, leading to fewer biochemical responses and les change in corneal aspherity. Good retinal image quality and satisfied quality of life were achieved at a comparable level in both study groups.

Early visual quality outcomes after small-incision lenticule extraction surgery for correcting high myopic astigmatism

Background

To evaluate early optical quality outcomes after small-incision lenticule extraction (SMILE) surgery for correcting high myopic astigmatism.

Methods

This retrospective study enrolled 55 eyes from 37 patients who had preoperative myopic astigmatism of ≥2.00 diopters (D) who had been treated with SMILE surgery. Preoperatively, the mean cylinder was − 2.41 ± 0.54 D (range, − 2.00 D to − 4.50 D). The preoperative and postoperative visual outcomes, refraction, and higher-order aberration (HOA) at 1 and 3 months were compared. Refractive astigmatism changes were analyzed by the Alpins vector method.

Results

Three months after SMILE surgery, the average cylinder was − 0.14 ± 0.31 D, and the average astigmatism vector was − 0.09 D × 6.34°. The angle of error (AofE) was limited to within ±10°, and the magnitude of error was limited to within ±1.0 D in all patients. The correction index (CI) was 0.98 ± 0.07, the index of success (IOS) was 0.08 ± 0.13, and the flattening index (FI) was 0.97 ± 0.07. Significant positive correlations were found between IOS and |AofE| (P = 0.000); negative correlations were found between FI and |AofE| (P = 0.000). The postoperative total HOA, spherical aberration, vertical coma aberration, and trefoil 30° were increased significantly compared with preoperative measurements, and the increase in HOA was closely related to preoperative astigmatism (P < 0.05).

Conclusions

SMILE has preferable outcomes for correcting high myopic astigmatism. Axis rotation during the surgery might influence the undercorrection of astigmatism. The increase of HOA after surgery is related to preoperative astigmatism.

Comparison of early visual outcomes after low-energy SMILE, high-energy SMILE, and LASIK for myopia and myopic astigmatism in the United States

PURPOSE

To compare uncorrected distance visual acuities (UDVAs) and induced higher-order aberrations (HOAs) in the early postoperative period between low-energy (LE) small-incision lenticule extraction (SMILE), high-energy (HE) SMILE, and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) procedures.

SETTING

University based refractive surgery center.

STUDY DESIGN

Retrospective cohort study.

METHODS

Records of patients who underwent SMILE or FS-LASIK were retrospectively reviewed. SMILE patients were separated into 2 groups: HE settings (125 nJ, 3.0 μm spot spacing) and LE settings (125-130 nJ, 4.5 μm spot spacing). UDVA was measured at postoperative day (POD) 1. Corneal HOAs and UDVA were measured at postoperative month (POM) 1. Induced spherical aberration, vertical coma, horizontal coma, total coma, and total HOAs were calculated.

RESULTS

The study included 147 eyes of 106 patients, 49 in each group. For SMILE patients, the difference in mean UDVA at POD1 was highly statistically significant in favor of the LE group (-0.003 vs 0.141, P < .0001). No significant difference in mean UDVA at POD1 was noted between the LE group and FS-LASIK group (-0.003 vs -0.011, P = .498). Induced change in spherical aberration was less in LE SMILE than that in FS-LASIK (0.136 vs 0.186 μm, P = .02) at POM1. No significant differences in POM1 mean UDVA (-0.033 vs -0.036) or induced change in all other HOAs were noted between LE SMILE and FS-LASIK.

CONCLUSIONS

LE settings were associated with significantly improved POD1 UDVA. POD1 and POM1 UDVA were comparable with those of FS-LASIK. Spherical aberration induction was less with LE SMILE than that with FS-LASIK, whereas all other induced HOAs were comparable with FS-LASIK.

Refractive and visual outcomes of small incision lenticule extraction (SMILE) in eyes with thin corneas

OBJECTIVES

To report the refractive and visual outcomes of small incision lenticule extraction (SMILE) with the thinnest corneal thickness (CCT) of less than 500 µm and evaluate it in terms of safety and efficacy.

SETTING

Refractive Surgery Clinic of University of Health Sciences Beyoglu Eye Training and Research Hospital, Istanbul, Turkey.

DESIGN

Retrospective case series.

METHODS

The pre-and-postoperative examinations of all patients with thin corneas (preoperative CCT <500 µm) who underwent the SMILE procedure and had a minimum of 24 months of follow-up records were reviewed from medical files. The main outcome measures of the refractive and visual outcomes and the effect on corneal high order aberrations (HOAs) were evaluated.

RESULTS

The study included 55 eyes of 39 patients. The mean preoperative uncorrected visual acuity (UDVA) was 1.3 ± 1.5 logMAR, and the mean postoperative UDVA was significantly improved to 0.05 ± 0.80 logMAR at the last visit (p < 0.001). At the last follow-up, 84% of the eyes were within ± 0.50D, and 96% of the eyes were within ±1.00D of attempted SE refraction. The HOAs of coma (p < 0.001), secondary astigmatism (p = 0.015), spherical aberration (p < 0.001), and RMS (p < 0.001) aberrations increased significantly from the baseline to the postoperative last visit. The increase in trefoil was not significant (p = 0.32). No sight threatening complications or ectasia were observed during the follow-up time.

CONCLUSION

SMILE is a safe and effective technique with long-term stability for treatment of myopia in eyes with a thin cornea, and satisfactory results can be obtained if candidates for surgery are selected carefully with particular emphasis on normal preoperative corneal topography.

[Small Incision Lenticule Extraction (SMILE) for correction of myopic astigmatism]

PURPOSE

To study the efficacy, stability, safety and predictability of small incision lenticule extraction (SMILE) at 1 day and 3 months postoperatively for moderate and high myopic astigmatism. To describe a simple and convenient method for detection and manual compensation of cyclotorsion during the procedure.

METHODS

In this retrospective study, a total of 164 eyes from 114 patients over 20 years of age with at least 1.5 diopters (D) of myopic astigmatism were treated by SMILE. Any cyclotorsion was manually compensated by gently rotating the cone to align the horizontal marks on the cornea to the 0° to 180° axis of the reticule after activating the suction.

RESULTS

The mean preoperative spherical equivalent (SE) was -5.3±2.01 D, and the mean cylinder was -2.01±0.67 D. Three months after surgery, a total of 87% of eyes were within±0.50 D of attempted post-operative SE, and 98% of eyes were within±1.00 D. Overall, the predictability of cylinder correction was excellent, with 96.3% of eyes within±1.00 D of attempted post-operative cylinder. The mean postoperative cylinder at three months was -0.3±0.39 D. We noted a slight undercorrection with treatment of high cylinder. However, 82% of eyes achieved postoperative refractive astigmatism less than 0.5 D. 91% of eyes achieved uncorrected distance visual acuity (UDVA) equal to or better than 8/10. 22% of eyes gained one line of visual acuity.

CONCLUSION

SMILE is a predictable and safe technique for the surgical correction of astigmatism. Manual compensation may be an effective approach to improve astigmatic outcomes of SMILE, especially in moderate and high astigmatism.

Comparison of refractive outcomes and high-order aberrations after small incision lenticule extraction and wavefront-guided femtosecond-assisted laser in situ keratomileusis for correcting high myopia and myopic astigmatism

PURPOSE

To compare the results of using small incision lenticule extraction (SMILE) and wavefront-guided femtosecond-assisted laser in situ keratomileusis (WFG FS-LASIK) to correct high myopia and myopic astigmatism.

MATERIAL AND METHODS

The 94 eyes of 47 patients with high myopia or myopic astigmatism, if not both, who had undergone SMILE were compared with the 94 eyes of 47 patients with high myopia or myopic astigmatism, also if not both, who had undergone WFG FS-LASIK. Only eyes with high myopic or myopic astigmatism errors greater than - 6.0 diopter (D) spherical refraction and 0-3 D cylindrical refraction were included. Values of uncorrected distance visual acuity, corrected distance visual acuity, efficacy index, safety index, predictability, and high-order aberration between the patient groups were compared.

RESULTS

The SMILE and WFG FS-LASIK groups did not significantly differ according to sex or age. Values of preoperative and postoperative spherical refraction, cylindrical refraction, spherical equivalent, uncorrected distance visual acuity, and corrected distance visual acuity between the groups also did not significantly differ nor did values of predictability, the efficacy index, or the safety index. SMILE induced more coma and trefoil (p < 0.001), whereas WFG FS-LASIK induced more spherical aberration (p < 0.001).

CONCLUSION

Both SMILE and WFG FS-LASIK are efficient, safe, predictable procedures for correcting high myopia and myopic astigmatism. SMILE may induce more coma and trefoil, whereas WFG FS-LASIK may induce more spherical aberration.

Short and long term outcomes after small-incision lenticule extraction: A tertiary referral centre experience

PURPOSE

The objective of this study is to evaluate the preoperative and short- and long-term postoperative results in terms of visual acuity, refractive error, and corneal wavefront aberrations in patients with myopia and myopic astigmatism undergoing small incision lenticule extraction (SMILE).

METHODS

Seventy-nine eyes of 52 myopes with or without astigmatism (41 right and 38 left) were enrolled in this retrospective study. The measurements included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SE) and wavefront aberrations. All the measurements before and after SMILE surgery were systematically recorded.

RESULTS

Mean preoperative UDVA was 1.19±0.24 logMAR and improved to 0.06±0.17 logMAR at the 3-year postoperative follow-up. At the conclusion of the 3-year follow-up, UDVA was better than or equal to 20/20 and 20/25 in 73% and 84% of eyes, respectively. At 1 month postoperatively, CDVA was 0.05±0.23 logMAR and significantly lower than the preoperative CDVA, 0.02±0.04 log MAR (P>0.05). However, at 1 year and 3 years after surgery, CDVA showed a significant increase compared to preoperative CDVA. At the conclusion of the 3-year follow-up, SE was -0.47 D, and 69.6% and 83.5% of the eyes were within±0.50 D and±1.00 D, respectively, of the intended correction. HOA's, coma, and spherical aberration increased significantly. No significant change in trefoil was detected.

CONCLUSION

This study showed that SMILE produces a stable, safe outcome for surgical treatment of myopia and myopic astigmatism.

Quality of life impact of refractive correction (QIRC) results three years after SMILE and FS-LASIK

Background

This study aimed to compare long-term postoperative quality of life and satisfaction differences between SMILE and FS-LASIK for myopia correction.

Methods

This cross-sectional study enrolled patients under the age of 39 years, who chose to undergo SMILE or FS-LASIK surgery to both eyes 3 years previously. Patients completed a common vision test and Quality of Life Impact of Refractive Correction (QIRC) questionnaire, together with the surgical satisfaction, adverse symptoms subjective survey. Patients with preoperative corrected distance visual acuity and postoperative uncorrected distance visual acuity of 20/20 or greater were included. Propensity score matching (PSM) was used to match the preoperative and postoperative spherical equivalent, age, and designed optical zones of the left and right eyes between the two groups.

Results

Forty-nine patients were included in each group after PSM from 188 patients. No significant difference in the total QIRC score was found between the SMILE and FS-LASIK groups (45.89 ± 5.91 vs 45.09 ± 5.65, p = 0.492). There were no differences in surgical satisfaction between the groups (p = 0.178). Compared to the SMILE group, the FS-LASIK group had more glare (2.12 ± 2.25 vs 3.22 ± 2.54, p = 0.026) and severe dryness (1.80 ± 1.98 vs 2.79 ± 2.19, p = 0.021).

Conclusion

Postoperative quality of life is similar after SMILE or FS-LASIK. Dry eye symptoms and glare were milder in the SMILE group than in the FS-LASIK group.

Small Incision Lenticule Extraction (SMILE) for Moderate and High Myopia: Seven-Year Outcomes of Refraction, Corneal Tomography, and Wavefront Aberrations

Purpose

To investigate the long-term outcomes of refraction, corneal tomography, and wavefront aberrations after small incision lenticule extraction (SMILE) for moderate and high myopia.

Methods

Prospective, nonconsecutive case series. A total of 26 patients (26 eyes) who underwent SMILE from May 2010 to March 2013 at the Fudan University Eye and ENT Hospital (Shanghai, China) were enrolled. The periods of follow-up were 1 month, 1 year, 5 years, and 7 years after surgery. The routine eye examinations included uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), manifest refraction, and corneal tomography.

Results

All surgeries were executed without any complications. At the final visit, an UDVA of 20/20 or better was achieved in 26 eyes (100%) and 11 eyes (42%) exhibited no change in CDVA. 9 eyes (35%) gained one line, 6 eyes (23%) gained two lines, and no eyes lost CDVA. 24 eyes (92%) and 26 eyes (100%) were within ±0.5 D and ±1.00 D of the target refraction, respectively. A mean refractive regression of −0.17 D was observed between 1 month and 7 years postoperatively. Mean corneal front curvature (MCFC) was significantly decreased between pre- and post-SMILE surgery (P < 0.0001). Higher-order aberrations (HOAs) and vertical coma were significantly increased after SMILE compared to those measured before surgery (all P < 0.001). There were no significant differences in trefoil and spherical aberration between pre- and post-SMILE surgery (all P > 0.05).

Conclusion

SMILE is an effective, safe, and stable procedure for moderate and high myopia, with relatively constant corneal stability and wavefront aberrations. This trial is registered with ChiCTR-ONRC-13003114.

Four-year outcomes of small incision lenticule extraction (SMILE) to correct high myopic astigmatism

AIMS

To evaluate the long-term outcomes of small incision lenticule extraction (SMILE) in subjects with myopic astigmatism of ≥2.00 dioptres (D).

METHODS

Patients who underwent SMILE 4 years prior with astigmatism ≥2.00 D and ≤1.00 D were assigned to the high astigmatic group (HA group) or the low astigmatic group (LA group), respectively. The visual and refractive results as well as corneal wavefront aberrations were measured.

RESULTS

The preoperative cylinder was -2.47±0.54 D in 43 eyes in the HA group and -0.55±0.28 D in 31 eyes in the LA group. At 4 years, the residual cylinder was -0.31±0.29 D in the HA group and -0.20±0.28 D in the LA group (p=0.088). An uncorrected distance visual acuity of 20/20 was achieved in 88.4% of eyes in the HA group and 93.5% of eyes in the LA group. The efficacy index was 0.99±0.14 and 1.10±0.21 (p=0.025), and the safety index was 1.11±0.20 and 1.22±0.21 in the HA and LA groups, respectively (p=0.012). Eighty-six per cent and 90.3% of eyes were within ±0.50 D of the attempted cylindrical correction in the HA and LA groups, respectively. Vector analysis showed that the magnitude of error was -0.14±0.28 D and -0.05±0.16 D (p=0.085), the angle of error was -0.13±4.48 degrees and -2.57±29.42 degrees (p=0.592), the correction index was 0.94±0.13 and 0.94±0.35 (p=0.959), the index of success was 0.15±0.14 and 0.46±0.62 (p=0.517), and the flattening index was 0.93±0.13 and 0.71±0.59 (p=0.450) in the HA and LA groups, respectively.

CONCLUSIONS

This study demonstrates that SMILE is effective and safe for correcting high astigmatism. Vector analysis shows a tendency for the undercorrection of astigmatism in subjects with high astigmatism.

Small-Incision Lenticule Extraction (SMILE) for the Correction of Myopia with Astigmatism: Outcomes of the United States Food and Drug Administration Premarket Approval Clinical Trial

PURPOSE

To present outcomes of the United States Food and Drug Administration premarket approval clinical trial of small-incision lenticule extraction (SMILE) for the correction of myopia and astigmatism.

DESIGN

Prospective, multicenter clinical trial.

PARTICIPANTS

The study included 357 eyes of 357 patients treated with SMILE (50 for myopia and 307 for myopia with astigmatism). Preoperative sphere ranged between -1.00 and -10.00 diopters (D), with manifest spherical equivalent (MSE) of up to -11.50 D and refractive cylinder of up to -3.00 D.

METHODS

-Participants were followed up for 12 months. Corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA), stability of the manifest refraction, and vector analysis of refractive cylinder are presented for the 307 eyes treated for myopia with astigmatism. Adverse events (AEs) are presented for all 357 eyes.

MAIN OUTCOME MEASURES

Corrected distance visual acuity, uncorrected distance visual acuity, manifest refraction, astigmatic outcomes, and adverse events.

RESULTS

Of the 307 astigmatic eyes enrolled in the study, 304 were treated successfully. In 3 eyes, the procedure was aborted because of intraoperative suction loss. The mean MSE reduced from -5.39±2.30 D at baseline to -0.01±0.24 D at 12 months. Of all eyes, 95.3% were within 0.50 D of emmetropia at 12 months. The percentage of eyes with UDVA of 20/20 or better was 89.0%. No loss of 2 or more lines of CDVA was observed at the 12-month visit. The refractive cylinder reduced from -1.53±0.70 D at baseline to -0.18±0.31 D at 12 months. The mean correction ratio of refractive cylinder was 0.96±0.16 and a slight undercorrection was apparent for higher attempted corrections of astigmatism. Three intraoperative AEs associated with difficult lenticule removal and resultant cap tear occurred, and all resolved without sequelae at postoperative day 1. During the postoperative period, 8 AEs were recorded, but none of them had significant consequences.

CONCLUSIONS

Small-incision lenticule extraction for the treatment of myopia and astigmatism was safe and effective, and the reported AEs had no significant impact on visual acuity. Slight undercorrection of refractive cylinder requires further attention.

Visual Outcomes after Small Incision Lenticule Extraction and Femtosecond Laser-Assisted LASIK for High Myopia

PURPOSE

The aim of this study was to compare visual outcomes after small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for high myopia.

METHODS

In this prospective, comparative study, a total of 52 eyes of 34 consecutive highly myopic patients with spherical equivalent within the range of -8.00 to -10.00 diopters were recruited. Twenty-three eyes of 16 patients were in the FS-LASIK group and 29 eyes of 18 patients were in the SMILE group. Visual outcomes and wavefront aberrations were analyzed preoperatively and 6 months postoperatively.

RESULTS

At the postoperative 6-month visit, 96.6% in the SMILE group and 91.3% in the FS-LASIK group achieved unchanged or better corrected distance visual acuity (CDVA). As for uncorrected distance visual acuity (UDVA), 96.6% in the SMILE group and 95.7% in the FS-LASIK group achieved UDVA of 20/20 or better. As for wavefront aberrations, high-order aberrations (HOAs) and spherical aberrations increased significantly after surgery in both groups relative to corresponding preoperative values (p < 0.001), and vertical coma increased after SMILE (p < 0.001). No statistically significant differences in changes of HOAs (p =0.90), spherical aberrations (p = 0.07), horizontal coma (p = 0.56), coma (p =0.08), horizontal trefoil (p =0.19), vertical trefoil (p = 0.90), and trefoil (p = 0.45) were detected between the 2 groups, except for vertical coma (p < 0.01).

CONCLUSIONS

SMILE is as effective as FS-LASIK in correcting high myopia, but attention should be paid to the induction of vertical coma in highly myopic patients following a SMILE procedure.

Evaluation of disk halo size after small incision lenticule extraction (SMILE)

PURPOSE

To investigate changes in objective disk halo size produced by a glare source after small incision lenticule extraction (SMILE) for myopia correction.

METHODS

This prospective clinical study included 45 right eyes of 45 patients with a mean age of 25.40 ± 5.06 years and mean spherical equivalent (SE) of - 6.08 ± 1.90 diopters. Disk halo size was measured with a vision monitor before surgery and at postoperative 1 week and 3 months. Other information was collected, including age, SE, lenticule thickness, lenticule diameter, dark pupil, and pupillary response to light parameters (initial diameter; amplitude, latency, duration, and velocity of contraction; latency, duration, and velocity of dilation; and maximum, minimum, and average pupil size).

RESULTS

Compared to preoperative values, disk halo size increased significantly at postoperative 1 week (P = 0.026) and returned to baseline at postoperative 3 months (P = 0.349). Preoperative disk halo size significantly correlated with SE (r = - 0.346, P = 0.020), minimum pupil size (r = 0.365, P = 0.014), and average pupil size (r = 0.310, P = 0.038). Disk halo size at postoperative 1 week was significantly correlated with age (r = 0.324, P = 0.030) and minimum pupil size (r = 0.297, P = 0.047). Disk halo size at postoperative 3 months was significantly correlated with lenticule diameter (r = - 0.362, P = 0.015), initial diameter (r = 0.311, P = 0.037), maximum pupil size (r = 0.312, P = 0.037), minimum pupil size (r = 0.440, P = 0.002), and average pupil size (r = 0.373, P = 0.012).

CONCLUSIONS

After SMILE, disk halo size demonstrated a temporary increase and then returned to baseline.

Future Developments in SMILE: Higher Degree of Myopia and Hyperopia

Small incision lenticule extraction (SMILE) is a novel 1-step refractive procedure with femtosecond laser for the correction of myopia and myopic astigmatism. Although it has shown good clinical results in efficacy, safety, predictability, and stability, there are still some concerns. In this study, we review the published clinical outcomes of high myopia correction and exploration in hyperopia correction. Results have suggested that SMILE has acceptable outcomes in correction for high myopia <10.0 diopters (D), and it is a feasible and effective procedure for the treatment of hyperopia. However, it is unsuitable for the treatment of extremely high myopia because there is undercorrection and regression as existed in laser-assisted in situ keratomileusis (LASIK), and compound hyperopic astigmatism currently could not be corrected either. More technical and clinical improvements are required to make SMILE competitive.

Identification of separated lenticular planes using optical coherence tomography

PURPOSE

To discuss how optical coherence tomography can be used to identify separated lenticular planes during small incision lenticule extraction (SMILE).

METHODS

SMILE procedures were performed on 26 eyes of 13 patients. An anterior segment optical coherence tomography examination was performed after laser scan. Anterior segment optical coherence tomography examinations were conducted again both after separation of the anterior lenticular plane in the right eye and after separation of the posterior lenticular plane in the left eye. Lenticule extraction was then completed, followed by another anterior segment optical coherence tomography examination. Anterior segment optical coherence tomography was also conducted on both eyes on the first day after surgery. Each measurement consisted of four line scans along the 45°, 90°, 135°, and 180° meridians. The brightness scores were compared between the two planes after the separation of one plane.

RESULTS

Anterior segment optical coherence tomography showed two bright lines after laser scan. Along with all meridians, the brightness of the anterior plane was less in the right eye, for which only the anterior plane was separated, and the brightness of the posterior plane was less in the left eye, for which only the posterior plane was separated (all P < 0.001). After lenticule extraction in both eyes, anterior segment optical coherence tomography revealed that a smooth hyperreflective line existed between the cap and the residual stromal bed, and this line remained throughout the first day after surgery.

CONCLUSION

The bubbles produced by the creation of the lenticule in SMILE mostly disappear by manual separation, and anterior segment optical coherence tomography can help the surgeon identify the separated lenticular planes.

Visual and refractive outcomes of 100 small incision lenticule extractions (SMILE) in moderate and high myopia: a 24-month follow-up study

PURPOSE

We aimed to present the visual results obtained in 100 small incision lenticule extraction (SMILE) refractive surgeries, demonstrate whether the technique is effective in the treatment of moderate and high myopia, and observe the follow-up of these patients over 24-month period.

METHODS

One hundred eyes of 50 consecutive patients were treated with SMILE. The preoperative spherical equivalent refraction was - 5.64 ± 1.23 D. During the postoperative period, patients were examined at 3, 6, 12, and 24 months. We analysed the efficacy, safety, predictability, and stability of the technique.

RESULTS

The Snellen visual acuity of 99% of the patients was 20/20 or better after 24 months of follow-up. Two eyes had a loss of two lines of visual acuity; 1% of the patients had a loss of one line of visual acuity. The postoperative spherical refraction was - 0.04 ± 0.35 D (- 1.00 to 0.50 D). The postoperative spherical equivalent refraction was - 0.19 ± 0.38 D (- 1.25 to 0.50 D). Eighty-three percent of the eyes were within ± 0.50 D, and 87% obtained a residual astigmatism of 0.50 D or less.

CONCLUSION

The SMILE technique was demonstrated to be an effective, predictable, safe, and stable technique in the treatment of moderate-to-severe myopia during the 24-month follow-up. Long-term follow-up should be undertaken to observe possible refractive regressions.

Five-year results of small incision lenticule extraction (SMILE) and femtosecond laser LASIK (FS-LASIK) for myopia

PURPOSE

To compare visual outcomes and aberration outcomes in small incision lenticule extraction (SMILE) versus femtosecond laser LASIK (FS-LASIK).

METHODS

This prospective, comparative, nonrandomized clinical study included 68 eyes of 37 patients receiving SMILE and 55 eyes of 30 patients receiving FS-LASIK between December 2011 and January 2013 at the Fudan University Eye and ENT Hospital (Shanghai, People's Republic of China). Patients were followed up at 3, 6 months and 5 years after surgery. Main outcome measurements included uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refraction, central corneal thickness (CCT), total corneal refractive power (TCRP) and wavefront aberrations.

RESULTS

About 98% (49/50) of treated eyes in the SMILE group and 95% (39/41) in the FS-LASIK group had a postoperative logMAR UDVA of 0 or better. Spherical equivalent (SE) after 5 years was -0.01 ± 0.35 D in the SMILE group and -0.23 ± 0.41 D in the FS-LASIK group. A regression of -0.02 ± 0.39 D in the SMILE group and -0.12 ± 0.32 D in the FS-LASIK group was observed between 6 months and 5 years postoperative time-points. TCRP increased by 0.39 ± 0.38 D in the SMILE group and 0.45 ± 0.49 D in the FS-LASIK group between 6-month and 5-year time-points. However, no statistically significant difference was found between the SMILE and FS-LASIK groups in terms of ∆SE, ∆CCT and ∆TCRP between 6 months and 5 years postoperative time-points.

CONCLUSION

Myopic regression was observed in terms of TCRP but not in subjective refraction. No statistically significant difference in stability was found between SMILE and FS-LASIK.

A Multicenter Study on Early Outcomes of Small-Incision Lenticule Extraction for Myopia

This study was aimed to investigate the early clinical outcomes of small-incision lenticule extraction (SMILE) to correct both myopia and myopic astigmatism at major clinical centers in Japan. This case series consisted of two hundred fifty-two eyes of 130 consecutive patients who underwent SMILE surgery (29.5 ± 6.3 years, mean age ± standard deviation), with spherical equivalents of -4.33 ± 1.61 D. We determined the safety, efficacy, predictability, stability, and adverse events of this procedure. Corrected distance visual acuity significantly improved, from -0.18 ± 0.04 preoperatively to -0.19 ± 0.07 logMAR postoperatively (paired t-test, p < 0.001). Uncorrected distance visual acuity also significantly improved, from 1.05 ± 0.26 preoperatively to -0.15 ± 0.11 logMAR postoperatively (p < 0.001). 88% and 98% of eyes were within ± 0.5 and 1.0 D of the targeted correction, respectively. Changes in manifest spherical equivalent from 1 week postoperatively were 0.02 ± 0.35 D (p = 0.127). No vision-threatening complications were observed in any of the cases. SMILE performed well in the correction of myopic refractive errors, and we experienced no severe complications in this series, indicating its feasibility as a surgical option for the treatment of these eyes.

Visual and Refractive Outcomes of Small-Incision Lenticule Extraction in High Myopia: 5-Year Results

Purpose

To report long-term visual and refractive results of small-incision lenticule extraction (SMILE) in treatment of high myopia.

Materials and Methods

Medical records of patients who underwent SMILE for surgical correction of myopia or myopic astigmatism were retrospectively reviewed. Only patients with a preoperative spherical equivalent of subjective manifest refraction (SE) ≥ 6 D and a postoperative follow-up of 5 years were included in the study. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and SE were analyzed preoperatively and at 1-, 3-, and 5-year postoperative periods.

Results

Thirty-seven eyes of 37 patients were included in the study. The mean attempted SE was −7.47 ± 1.10 D (range −6.00 to −10.00 D). At the 5-year visit, the mean difference between achieved and attempted SE was −0.43 ± 0.47 (0.50 to −1.25 D). Mean postoperative UDVA and CDVA were 0.20 ± 0.18 and 0.06 ± 0.08 logMAR, respectively. At the 1-year visit, 70% and 97% of the eyes were within ±0.50 D and ±1.00 D of the intended correction. At the 5-year follow-up, 59% and 92% percent of the eyes were within ±0.50 D and ±1.00 D of the intended SE, respectively. At the 5-year visit, the efficacy index was 0.89 ± 0.26 and the safety index was 1.16 ± 0.20. Fifty-four percent of the eyes gained one or more lines of CDVA.

Conclusion

SMILE with an intended correction of up to a spherical equivalent of 10 D is safe and effective. However, there is regression of the refractive effect over extended follow-up.

Three-year outcomes of small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for myopia and myopic astigmatism

Aims

To compare long-term clinical outcomes following small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for myopia and myopic astigmatism correction.

Methods

In this retrospective study, we enrolled a total of 101 patients (101 eyes) who underwent SMILE or FS-LASIK 3 years prior. Measured parameters included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction and corneal wavefront aberrations.

Results

No significant differences in patient characteristics were found between the two groups. At the 3-year follow-up, UDVA was better than or equal to 20/20 in 90% and 85% (p=0.540) of the eyes; the efficacy indexes were 1.05±0.19 and 1.01±0.21 in the SMILE and FS-LASIK groups, respectively (p=0.352). Safety indexes were 1.19±0.17 and 1.15±0.20 in the SMILE and FS-LASIK groups, respectively (p=0.307). Eighty per cent and 65% of eyes were within ±0.50 D of the attempted spherical equivalent correction after SMILE and FS-LASIK, respectively (p=0.164). Vector analysis revealed no significant differences in astigmatic correction between the two groups (p>0.05). Surgically induced spherical aberration was higher in the FS-LASIK group than in the SMILE group (p<0.001).

Conclusion

Long-term follow-up analysis suggested that both SMILE and FS-LASIK were safe and equally effective for myopic and astigmatic correction.

Real-Time Intraocular Pressure Measurements in the Vitreous Chamber of Rabbit Eyes During Small Incision Lenticule Extraction (SMILE)

PURPOSE

To investigate real-time intraocular pressure (IOP) during small incision lenticule extraction (SMILE) in rabbit eyes for myopia correction.

METHODS

During SMILE, real-time IOP was measured in the vitreous cavity of rabbit eyes with an optic fiber pressure sensor (OFPS). Two groups (n = 6 for each) underwent surgery, one group for a -2.00 diopter (D) refractive spherical correction and the other for a -6.00 D correction.

RESULTS

During surgery, the IOP increased once the glass contact attached to the cornea (Pre-suction), and peaked 83.94 mmHg (SD ± 23.87 mmHg) for the -2.00 D group and 89.17 mmHg (SD ± 22.66 mmHg) for the -6.00 D group, both average values were less than 110 mmHg when suction was initiated to fix the glass contact onto the cornea (Suction on). It then fell to 74.81 mmHg (SD ± 20.64 mmHg) and 76.94 mmHg (SD ± 27.43 mmHg), respectively, and remained stable during lenticule creation (Cutting). After suction stopped (Suction off), IOP fell steeply. During lenticule separation/extraction, the change in IOP was 32.26 mmHg (SD ± 2.91 mmHg). Notably, the average duration of elevated IOP during the surgery was 166.05 s (no longer than 3 min).

CONCLUSIONS

The IOP fluctuations in the vitreous cavity using an OFPS in a rabbit model during SMILE showed that real-time IOP significantly was increased during Pre-suction, Suction on, Cutting, Suction off, and lenticule separation/extraction compared to baseline IOP, although, peaked at Suction on. Neither the degree of myopic correction nor central corneal thickness significantly affected these changes in IOP.

Predictability of the Achieved Lenticule Thickness in Small Incision Lenticule Extraction for Myopia Correction

PURPOSE

To investigate the predictability of the achieved lenticule thickness in small incision lenticule extraction (SMILE) for the correction of myopia.

METHODS

In this prospective study, a total of 80 eyes of 45 patients who underwent the SMILE procedure were included. A Scheimpflug camera was used to measure the preoperative and postoperative corneal topography. Achieved lenticule thicknesses at the pupil center and corneal vertex were calculated by subtracting the postoperative corneal thickness at the pupil center and corneal vertex from preoperative corresponding values. Predictability between the achieved and VisuMax readout at different locations (the pupil center and corneal vertex) and postoperative visits (postoperative day 1 and 6 months) were evaluated using a general linear model.

RESULTS

Achieved lenticule thickness at the pupil center and corneal vertex showed good correlation at both postoperative day 1 (pupil center: r=0.914, corneal vertex: r=0.903) and 6 months (pupil center: r=0.886, corneal vertex: r=0.866). The achieved lenticule thickness at postoperative day 1 was 8.5-μm thinner at the pupil center and 9.6-μm thinner at the corneal vertex than the VisuMax readout.

CONCLUSIONS

This study suggests that the predictability between the achieved and VisuMax readout is favorable. The lenticule thickness at the pupil center is closer to the VisuMax readout than corneal vertex.

Refractive lenticule extraction small incision lenticule extraction: A new refractive surgery paradigm

Small incision lenticule extraction (SMILE), a variant of refractive lenticule extraction technology is becoming increasingly popular, as a flapless and minimally invasive form of laser vision correction (LVC) for the treatment of myopia and myopic astigmatism. This review aims at summarizing the principles, surgical technique, and clinical outcomes in terms of visual and refractive results, safety, efficacy, postoperative dry eye, aberrations, and biomechanics of SMILE and its comparison with other conventional techniques of LVC, such as laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Recent advancements in the laser frequency and energy delivery patterns, instrumentation, and surgical techniques have shown significant improvement in the visual recovery and outcomes after SMILE, compared to the initial results published by Sekundo and Shah et al. Most of the recently published literature on long-term outcomes of SMILE shows excellent stability of the procedure, especially for higher myopia. In terms of the postoperative dry eye, SMILE shows a clear advantage over LASIK as numerous studies have shown significant differences about the Schirmer's, Tear film break up time, corneal sensitivity, and corneal nerve regeneration to be better following SMILE compared to LASIK. There is some evidence that since the Bowman's membrane (BM) and the anterior lamellae remain intact after SMILE, this may be a potential advantage for corneal biomechanics over LASIK and PRK where the BM is either severed or ablated, respectively, however, the data on biomechanics are inconclusive at present. Overall, this procedure has proved to be promising, delivering equivalent, or better visual and refractive results to LASIK and providing clear advantage in terms of being a flapless, minimally invasive procedure with minimal pain and postoperative discomfort thus offering high patient satisfaction.

Three-year results of small incision lenticule extraction and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis for correction of high myopia and myopic astigmatism

AIM

To compare and calculate the 3-year refractive results, higher-order aberrations (HOAs), contrast sensitivity (CS) and dry eye parameters after small incision lenticule extraction (SMILE) and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for correction of high myopia and myopic astigmatism.

METHODS

In this prospective, non-randomized comparative study, 78 eyes with spherical equivalent (SE) of -8.11±1.09 diopters (D) received a SMILE surgery, and 65 eyes with SE of -8.05±1.12 D received a wavefront-guided FS-LASIK surgery with the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) for flap cutting. Visual acuity, manifest refraction, CS, HOAs, ocular surface disease index (OSDI) and tear break-up time (TBUT) were evaluated during a 3-year follow-up.

RESULTS

The difference of uncorrected distance visual acuity (UDVA) postoperatively was achieved at 1mo and at 3mo, whereas the difference of the mean UDVA between two groups at 3y were not statistically significant (t=-1.59, P=0.13). The postoperative change of SE was 0.89 D in the FS-LASIK group (t=5.76, P=0.00), and 0.14 D in the SMILE group (t=0.54, P=0.59) from 1mo to 3y after surgery. At 3-year postoperatively, both HOAs and spherical aberrations in the SMILE group were obviously less than those in the FS-LASIK group (P=0.00), but the coma root mean square (RMS) was higher in the SMILE group (0.59±0.26) than in the FS-LASIK group (0.29±0.14, P=0.00). The mesopic CS values between two groups were not statistically significant at 3y postoperatively. Compared with the FS-LASIK group, lower OSDI scores and longer TBUT values were found in the SMILE group at 1mo and 3mo postoperatively. With regard to safety, no eye lost any line of CDVA in both groups at 3y after surgery.

CONCLUSION

Both SMILE and wavefront-guided FS-LASIK procedures provide good visual outcomes. Both procedures are effective and safe, but SMILE surgery achieve more stable long-term refractive outcome and better control of early postoperative dry eye as compared to FS-LASIK.