Comparison of early visual quality in patients with moderate myopia using different optical zones in small incision lenticule extraction (SMILE)

Subjective patient-reported visual quality after small-incision lenticule extraction and its correlation to the objective one

PURPOSE

The purpose of the study was to characterize the subjective visual quality and satisfaction following small-incision lenticule extraction (SMILE) and to identify its influential factors.

SETTING

Peking University Third Hospital, Beijing, China.

DESIGN

This was a retrospective observational study.

METHODS

Patients who had simultaneous binocular SMILE for myopia and myopic astigmatism were included 6 months postoperatively, and the patient-reported outcome questionnaire was employed for the assessment of visual quality in real-life situations. Examinations with SIRIUS combined corneal topography and tomography were performed including the parameters of Strehl ratio (SR), corneal higher-order aberrations (HOAs) within 6.0-mm area, kappa angel, and thinnest corneal thickness. Decentration and effective optical zone (EOZ) were measured based on a tangential pre-post-operation difference map. Binary logistic regression analysis was performed for predictors of patient-reported visual quality.

RESULTS

Clinical data from 97 cases were analyzed retrospectively. Overall satisfaction was 96.91% (94/97). Fluctuation in vision and glare is the most frequent and dominant visual symptoms. SR value increased non-significantly compared with preoperative (P> 0.05). A statistically significant (P < 0.05) increase in total HOAs, spherical aberration, and coma was noted. SR and HOAs were not correlated with the degree of visual symptoms (P > 0.05). No objective parameter was found to be associated with patient-reported visual quality after SMILE (P> 0.05).

CONCLUSION

The high patient-reported satisfaction confirmed the ideal effect on visual quality following SMILE in real-life situations, though some objective optical performances were not satisfying. It is very tolerant toward patients' conditions and mild deviations, and this study did not find factors affecting visual performances.

Intensive topical steroid regimen for enhanced very early recovery after small incision lenticule extraction

OBJECTIVE

This study aims to investigate the topical steroid regimen after small incision lenticule extraction (SMILE) for its effect on very early restoration of visual quality.

METHODS

A total of 180 patients (360 eyes) who underwent SMILE were enrolled. These patients were randomly assigned to three groups, with 60 patients in each group. The only difference among these three groups was the administration of 0.1% fluorometholone (FML) eye drops within two hours after SMILE: no FML in group A, 0.1% FML once every hour in group B and 0.1% FML once every half hour in group C. The corrected distance visual acuity (CDVA), objective scattering index (OSI), modulation transfer function (MTF) cut-off, Strehl ratio (SR) and incidence of subjective symptoms were evaluated preoperatively, at 2, 4 and 24 h and one week after SMILE.

RESULTS

The CDVA, MTF cut-off and SR values were significantly higher in group C, when compared to the other two groups, at 2 and 4 h after SMILE (p < 0.05). Furthermore, the OSI and incidence of subjective symptoms were significantly lower in group C, when compared to the other two groups, at 2 and 4 h after SMILE (p < 0.05). However, no significant differences in CDVA, MTF cut-off, SR, OSI and the incidence of subjective symptoms were detected among the three groups at 24 h and one week after SMILE (p > 0.05).

CONCLUSION

The administration of 0.1% FML eye drops every half hour within two hours after SMILE accelerates the restoration of visual and optical quality, and reduces the incidence of subjective symptoms during the very early phase after surgery.

Impact of Dry Eye Disease on the Uncorrected Distance Visual Acuity after Small Incision Lenticule Extraction

The aim of this study was to explore the impact of dry eye disease (DED) on the uncorrected distance visual acuity (UDVA) and refractive status after small incision lenticule extraction (SMILE). This prospective cohort study enrolled 29 patients (DED group, 11 eyes; non-DED group, 18 eyes) who underwent SMILE in our center from July to September 2022. The examinations on DED, refractive status and UDVA were performed before surgery, and on day 7 and 20 after surgery. The results showed that on day 20 after SMILE, subjects in the non-DED group reported greater changes of ocular surface disease index value increase and tear-film breakup time reduction compared to baseline than those in the DED group (p < 0.001 and p = 0.048, respectively). Compared to preoperative status, DED patients had greater improvements of UDVA and better optometric outcomes on day 20 after surgery than non-DED subjects (p = 0.008 and 0.026, respectively). Multiple linear regression analysis showed age, contact lens daily wearing time, and tear meniscus height before surgery were of the highest value to predict UDVA on day 20 after SMILE in contact lens wearers (p = 0.006, 0.010 and 0.043, respectively). In conclusion, preoperative tear function could affect UDVA after SMILE. The impact of DED on UDVA and refraction should be taken into consideration before surgery.

The effects of programmed optical zones on achieved corneal refractive power with myopic astigmatism after small incision lenticule extraction (SMILE): a vector analysis

PURPOSE

To evaluate the effects of different programmed optical zones (POZs) on achieved corneal refractive power (CRP) with myopic astigmatism after small incision lenticule extraction (SMILE).

METHODS

In total, 113 patients (113 eyes) were included in this retrospective study. The eyes were divided into two groups according to POZ: group A (6.5, 6.6, and 6.7 mm, n = 59) and group B (6.8, 6.9, and 7.0 mm, n = 54). Fourier vector analysis was applied to evaluate the error values between the attempted and achieved corneal refractive power (CRP). Alpins vector analysis was used to calculate surgically induced astigmatism (SIA), difference vector (DV), magnitude of error (ME), and astigmatism correction index (ACI). Multivariate regression analysis was performed to assess potential factors associated with the error values.

RESULTS

The error values in the group with large POZ were closer to zero, and significantly associated with the POZ at 2 and 4 mm of the cornea (β =  - 0.50, 95% confidence interval [CI] [- 0.80, - 0.20]; β =  - 0.37, 95% CI [- 0.63, - 0.10], P < 0.05, respectively). For the correction of astigmatism, the values of SIA, ME, and ACI were lower in group B than in group A (P < 0.05). The fitting curves between TIA and SIA were y = 0.83x + 0.19 (R² = 0.84) and y = 1.05x + 0.04 (R² = 0.90), respectively.

CONCLUSIONS

Smaller POZs resulted in higher error values between the achieved- and attempted-CRP in the SMILE procedure, which should be considered when performing surgery.

Comparison of Postoperative Safety, Efficacy, and Visual Quality after SMILE for Myopic Patients with Different Corneal Thicknesses

PURPOSE

To investigate the safety, efficacy, and visual quality of small incision lenticule extraction (SMILE) in different corneal thickness patients with myopia or myopic astigmatism.

METHODS

This prospective cohort study included 191 right eyes of 191 patients. Eyes were divided into three groups according to preoperative central corneal thickness (CCT) (Preoperative central corneal thickness (CCT) was the group indicator.) There were 31 eyes in the thin cornea group (CCT ≤500 um (μm), TC), 94 eyes in the moderate corneal thickness group (CCT ≥501 um (μm) and ≤550 um (μm), MD) and 66 eyes in the thick cornea group (CCT ≥550 um (μm), TK). Comparisons in uncorrected (UDVA) and best-corrected distance visual acuity (BDVA), manifest refractive spherical equivalent (SE), preoperative mesopic/photopic contrast sensitivity (CS), ocular higher-order aberrations (HOAs) at a 6mm analytical pupil diameter, and visual quality questionnaires were made (performed) among the three groups during the postoperative six months. Subgroup analyses were made based on preoperative SE.

RESULTS

The safety indices at six months were 1.15 ± 0.18, 1.14 ± 0.17, and 1.18 ± 0.17, respectively (p = 0.374), and the efficacy indices at six months were 1.07 ± 0.25, 1.12 ± 0.22, and 1.11 ± 0.21, respectively (p = 0.599). The postoperative SE was -0.07 ± 0.52D, -0.14 ± 0.38D, and -0.05 ± 0.46D after SMILE in the three groups, respectively (p = 0.376). No significant difference was found in mesopic/photopic CS, HOAs, and visual quality among different corneal thickness groups and SE groups. Postoperative SE and efficacy indices were the lowest in thin cornea eyes with ultra-high myopia (over -9.00 D).

CONCLUSIONS

SMILE provides comparable safety, efficacy, and visual quality results in different corneal thickness patients. Those with myopia higher than -9.00 D had less efficacy after surgery, especially in thin cornea patients.

Applying Information Gain to Explore Factors Affecting Small-Incision Lenticule Extraction: A Multicenter Retrospective Study

Purpose

This retrospective study aimed to identify the key factors influencing postoperative refraction after small-incision lenticule extraction (SMILE) using information gain.

Methods

This study comprised 2,350 eyes of 1,200 patients who underwent SMILE using a Visumax 500-kHz femtosecond laser (Carl Zeiss Meditec AG) in three ophthalmic centers: Tianjin Eye Hospital (center A), Jinan Mingshui Eye Hospital (center B), and Qingdao Eye Hospital (center C). Anterior segment features, including corneal curvature and central corneal thickness (CCT), were obtained from Pentacam HR (Oculus, Wetzlar, Germany). Information gain was calculated to analyze the importance of features affecting postoperative refraction.

Results

Preoperative and postoperative mean spherical equivalent (SE) refraction were −5.00 (−6.13, −3.88) D and 0.00 (−0.25, 0.13) D, respectively. None of the patients lost more than two lines of corrected distance visual acuity. The safety index was 1.32 ± 0.24, 1.03 ± 0.08, and 1.13 ± 0.16 in centers A, B, and C, respectively. The efficacy index was 1.31 ± 0.25, 1.02 ± 0.08, and 1.13 ± 0.17 in centers A, B, and C, respectively. At least 95% of the eyes were within ±1.00 D of the attempted correction. Postoperative refraction was related to preoperative spherical diopter refraction (r = 0.369, p < 0.001), preoperative SE (r = 0.364, p < 0.001), maximum lenticule thickness (r = −0.311, p < 0.001), preoperative uncorrected distance visual acuity (r = 0.164, p < 0.001), residual stromal thickness (r = 0.139, p < 0.001), preoperative mean anterior corneal curvature (r = −0.127, p < 0.001), preoperative flattest anterior corneal curvature (r = −0.122, p < 0.001), nomogram (r = −0.100, p < 0.001) and preoperative CCT (r = −0.058, p = 0.005).

Conclusions

SMILE was considered a safe and effective procedure for correcting myopia. Based on information gain, postoperative refraction was influenced by preoperative mean anterior corneal curvature, CCT, refraction, and residual stromal thickness.

Clinical outcomes after small-incision lenticule extraction versus femtosecond laser-assisted LASIK for high myopia: A meta-analysis

AIM

To compare postoperative clinical outcomes of high myopia after small-incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK).

METHODS

From March 2018 to July 2020, PubMed, MEDLINE, Embase, the Cochrane Library, and several Chinese databases were comprehensively searched. The studies meeting the criteria were selected and included; the data were extracted by 2 independent authors. The clinical outcome parameters were analyzed with RevMan 5.3.

RESULTS

This meta-analysis included twelve studies involving 766 patients (1400 eyes: 748 receiving SMILE and 652 receiving FS-LASIK). Pooled results revealed no significant differences in the following outcomes: the logarithm of the mean angle of resolution (logMAR) of postoperative uncorrected distance visual acuity (weighted mean difference (WMD) = -0.01, 95% confidence interval (CI): -0.02 to 0.00, I2 = 0%, P = 0.07 at 1 mo; WMD = -0.00, 95% CI: -0.01 to 0.01, I2 = 0%, P = 0.83 at 3 mo; WMD = -0.00, 95% CI: -0.01 to 0.00, I2 = 32%, P = 0.33 in the long term), and the postoperative mean refractive spherical equivalent (WMD = -0.03, 95% CI: -0.09 to 0.03, I2 = 13%, P = 0.30). However, the SMILE group had significantly better postoperative corrected distance visual acuity (CDVA) than the FS-LASIK group (WMD = -0.04, 95% CI, -0.05 to -0.02, I2 = 0%, P<0.00001). In the long term, postoperative total higher-order aberration (WMD = -0.09, 95% CI: -0.10 to -0.07, I2 = 7%, P<0.00001) and postoperative spherical aberration (WMD = -0.15, 95% CI: -0.19 to -0.11, I2 = 29%, P<0.00001) were lower in the SMILE group than in the FS-LASIK group; a significant difference was also found in postoperative coma (WMD = -0.05, 95% CI: -0.06 to -0.03, I2 = 30%, P<0.00001).

CONCLUSION

For patients with high myopia, both SMILE and FS-LASIK are safe, efficacious and predictable. However, the SMILE group demonstrated advantages over the FS-LASIK group in terms of postoperative CDVA, while SMILE induced less aberration than FS-LASIK. It remains to be seen whether SMILE can provide better visual quality than FS-LASIK; further comparative studies focused on high myopia are necessary.