scholarly journals Investigation of Predictability and Influence factors of the Achieved Lenticule Thickness in Small Incision Lenticule Extraction

2019 ◽  
Author(s):  
Fang Wu ◽  
Houfa Yin ◽  
Xinyi Chen ◽  
Yabo Yang
Keyword(s):  
Linear Regression ◽  
Linear Regression Analysis ◽  
Influence Factors ◽  
Small Incision Lenticule Extraction ◽  
Pupil Center ◽  
Small Incision ◽  
Significant Relationships ◽  
Ultrasound Pachymetry ◽  
Lenticule Extraction ◽  
The Difference

Abstract Background To evaluate the differences between the predicted and achieved lenticule thickness (ΔLT) after small incision lenticule extraction (SMILE) surgery and investigate relationships between ΔLT and refractive errors or lenticule depth in SMILE. Methods A total of 184 eyes from 184 consecutive patients who underwent SMILE were included in this prospective study. One eye for each patient was randomly selected and included for statistical analysis. An ultrasound pachymetry measurement and Scheimpflug camera corneal topography were obtained before and at 3 months after SMILE. The achieved lenticule thickness was calculated by comparing the preoperative examinations with postoperative examinations using ultrasound pachymetry and Pentacam software measurements. The pupil center and corneal vertex were selected as the 2 locations for measurement calculation on Pentacam. Analysis of variance (ANOVA) was performed to compare mean pachymetry values using different instruments. An independent t test was performed to evaluate the difference in ΔLT between different cap thicknesses. Linear regression analyses were performed between the VisuMax readout lenticule thicknesses and the measured maximum corneal change, the preoperative spherical equivalent (SE) and each ΔLT. Results On average, the achieved lenticule thickness measured with ultrasound pachymetry was 13.02 ± 8.87 μm thinner than the VisuMax readout lenticule thickness. Linear regression analysis showed significant relationships between the predicted and each achieved lenticule thickness. The preoperative SE was significantly related to each ΔLT (ultrasound: R2 =0.279; at corneal vertex: R2 =0.252; at pupil center R2 =0.246). The ΔLT measured by ultrasound pachymetry was significantly smaller in the thick cap group (cap thickness above 120 μm) than in the thin cap group (P < 0.01). Conclusions An overestimation of achieved lenticule thickness was found in this study. The ΔLT was related to the preoperative SE correction. Furthermore a lager ΔLT was found under a thin cap.

scholarly journals Effect of Preoperative Keratometry on Visual Outcomes After Small-incision Lenticule Extraction for Myopia

2021 ◽  
Author(s):  
Seongjun Lee ◽  
Sinwoo Bae ◽  
Moonsun Jung
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Linear Regression Analysis ◽  
Small Incision Lenticule Extraction ◽  
Visual Outcomes ◽  
Small Incision ◽  
Lenticule Extraction ◽  
Weak Negative Correlation ◽  
Single Standard ◽  
The Relationship

Abstract Purpose: To investigate the relationship between preoperative keratometry (K) and postoperative refraction, and compare the visual outcomes after small-incision lenticule extraction (SMILE) between preoperative flat and steep corneas.Methods: This study involved 814 consecutive eyes of 409 patients who underwent SMILE. A month later, a linear regression analysis of the relationship between preoperative K and the residual spherical equivalent (SE) along with eyes divided by a single standard deviation between flat and steep corneas (< 41.85 D, > 44.57 D, respectively) was conducted. Eyes were distinguished based on the degree of myopia. Results: One month after surgery, no significant correlation existed between mean preoperative K and residual SE (P = 0.459). Linear regression analysis showed a weak negative correlation between flat corneas (r2 = 0.042, P =0.025) rather than steep corneas (P = 0.908). Eyes with preoperative low myopia (< 3.00 D) (r2 = 0.233, P = 0.001) had a weak correlation compared with moderate and high myopia (P = 0.272, P = 0.257, respectively). Twelve months later, the predictability, safety, and efficacy did not vary between preoperative flat and steep corneas (P > 0.05).Conclusions: One month after SMILE for myopia, the corneas were flatter in the preoperative flat corneas or all the low myopic corneas, and they were more overcorrected. However, preoperative corneal curvature does not influence visual outcomes at 1 year after SMILE.

scholarly journals Effect of preoperative keratometry on visual outcomes after small-incision lenticule extraction for myopia

2022 ◽  
Author(s):  
Seongjun Lee ◽  
Sinwoo Bae ◽  
Moonsun Jung
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Linear Regression Analysis ◽  
Small Incision Lenticule Extraction ◽  
Visual Outcomes ◽  
Small Incision ◽  
Lenticule Extraction ◽  
Weak Negative Correlation ◽  
Single Standard ◽  
The Relationship

Abstract Purpose To investigate the relationship between preoperative keratometry (K) and postoperative refraction and compare the visual outcomes after small-incision lenticule extraction (SMILE) between preoperative flat and steep corneas. Methods This study involved 814 consecutive eyes of 409 patients who underwent SMILE. A month later, a linear regression analysis of the relationship between preoperative K and the residual spherical equivalent (SE) along with eyes divided by a single standard deviation between flat and steep corneas (< 41.85 D, > 44.57 D, respectively) was conducted. Eyes were distinguished based on the degree of myopia. Results One month after surgery, no significant correlation existed between mean preoperative K and residual SE (P = 0.459). Linear regression analysis showed a weak negative correlation between flat corneas (r2 = 0.042, P = 0.025) rather than steep corneas (P = 0.908). Eyes with preoperative low myopia (< 3.00 D) (r2 = 0.233, P = 0.001) had a weak correlation compared with moderate and high myopia (P = 0.272, P = 0.257, respectively). Twelve months later, the predictability, safety, and efficacy did not vary between preoperative flat and steep corneas (P > 0.05). Conclusions One month after SMILE for myopia, the corneas were flatter in the preoperative flat corneas or all the low myopic corneas, and they were more overcorrected. However, preoperative corneal curvature does not influence visual outcomes at 1 year after SMILE.

Vector analysis of small incision lenticule extraction and toric implantable collamer lens implantation for astigmatism correction

2020 ◽  
pp. 112067212093060
Author(s):  
Ting Wan ◽  
Houfa Yin ◽  
Zhiyi Wu ◽  
Yabo Yang
Keyword(s):  
Vector Analysis ◽  
Small Incision Lenticule Extraction ◽  
Implantable Collamer Lens ◽  
Small Incision ◽  
Astigmatism Correction ◽  
Induced Astigmatism ◽  
Lenticule Extraction ◽  
The Difference ◽  
Surgically Induced ◽  
Myopic Astigmatism

Objectives: To compare the efficacy of small incision lenticule extraction (SMILE) and toric implantable collamer lens (TICL) implantation for myopic astigmatism correction using vector analysis. Methods: In this retrospective study, 171 eyes of 171 patients with cylinder ⩾1.0 diopters (D) were recruited, with 97 eyes underwent SMILE and 74 eyes underwent TICL implantation. Preoperative and 3-months postoperative visual and refractive results were examined. The astigmatism correction, graded by the degree of preoperative cylinder was compared between two groups using vector analysis. Results: At 3-months postoperatively, the residual cylinder was −0.10 ± 0.21 D in the SMILE group and −0.30 ± 0.32 D in the TCL group ( p < 0.05). Furthermore, 98% and 85% of eyes had the cylinder within ±0.5 D in the SMILE and TICL group, respectively. The vector analysis revealed similar target induced astigmatism vector in two groups. However, the difference vector, magnitude of error, angle of error, and index of success were significantly higher (0.30 ± 0.32 D, −0.19 ± 0.25, −2° ± 4.35°, and 0.16 ± 0.17 D, respectively) in the TICL group than the values in the SMILE group (0.10 ± 0.21 D, −0.05 ± 0.20, −0.03° ± 2.13°, and 0.05 ± 0.12, respectively), regardless of the degree of preoperative cylinder (all p < 0.05). For preoperative cylinder < 2.0 D, surgically induced astigmatism vector and correction index in the SMILE group were higher than those in the TICL group ( p < 0.05). Conclusion: Both SMILE and TICL implantation are effective techniques for myopic astigmatism correction. However, the accuracy of correction in the magnitude and axis of astigmatism with SMILE was better than that achieved with TICL implantation.

Comparison of Early Visual Quality in Patients using Different Optical Zones Based on Dark Pupil Diameters in Small Incision Lenticule Extraction (SMILE)

2021 ◽  
Author(s):  
Jiao Peng ◽  
Ding-Juan Zhong ◽  
Jia Liu ◽  
Li-Yuan Zhang ◽  
Hao Wu ◽  
...  
Keyword(s):  
Pupil Diameter ◽  
Visual Quality ◽  
Higher Order ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Group A ◽  
Optical Zone ◽  
Lenticule Extraction ◽  
The Difference ◽  
Group B

Abstract AIM: The early visual qualities of patients were evaluated after small incision lenticule extraction (SMILE) using different optical zones based on dark pupil diameters.METHODS: A case-control study was conducted to include 49 myopic patients (96 eyes) who underwent SMILE surgery. Patients were divided into three groups according to the difference between the diameter of the optical zone and the diameter of the dark pupil: Group A (<0 mm, N=30), Group B (0-1 mm, N=36), and Group C (>1 mm, N=30). In all groups, the dark pupil diameter was measured preoperatively. Subjective visual quality, uncorrected vision acuity (UCVA), spherical equivalent (SE), modulation transfer function cut-off frequency (MTFcutoff), objective scattering index (OSI), simulated contrast visual acuity (VA100%, VA20%, VA9%), total corneal higher-order aberration (tot-HOA), corneal spherical aberration (totZ40) and corneal coma (tot-coma) were measured preoperatively and 3 months postoperatively. P< 0.05 was considered statistically significant.RESULTS: There were no statistically significant differences in age, sex, UCVA, SE, corneal higher-order aberration, OQAS or subjective visual quality among the three groups before surgery (P>0.05). At 3 months postoperatively, there was no significant difference in UCVA, SE, MTFcutoff, OSI, VA100%, VA20%, or VA9% among the three groups (P>0.05). However, the tot-HOA, totZ40 and tot-coma indexes and the changes in corneal higher-order aberrations (Dtot-HOA, DtotZ40, Dtot-coma) at 3 months postoperatively were as follows: Group A > Group B > Group C (P<0.05). At 3 months postoperatively, the difference in subjective visual quality between the three groups was statistically significant (P<0.05). The difference in the amount of change in subjective visual quality between Groups A and C was statistically significant (P<0.05).CONCLUSION: Although the difference between the diameter of the optical zone and the diameter of the dark pupil does not affect the VA or the same diopter of patients after SMILE myopia correction, the optical zone diameter should be greater than the dark pupil diameter as far as possible in the design of SMILE surgery, in order to improve the objective visual quality and subjective satisfaction of patients after surgery.

scholarly journals SMILE and Wavefront-Guided LASIK Out-Compete Other Refractive Surgeries in Ameliorating the Induction of High-Order Aberrations in Anterior Corneal Surface

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Min-jie Ye ◽  
Cai-yuan Liu ◽  
Rong-feng Liao ◽  
Zheng-yu Gu ◽  
Bing-ying Zhao ◽  
...  
Keyword(s):  
Spherical Aberration ◽  
Laser In Situ Keratomileusis ◽  
Small Incision Lenticule Extraction ◽  
Corneal Surface ◽  
Small Incision ◽  
Significant Difference ◽  
Lenticule Extraction ◽  
A Prospective Study ◽  
High Order Aberrations

Purpose. To compare the change of anterior corneal higher-order aberrations (HOAs) after laser in situ keratomileusis (LASIK), wavefront-guided LASIK with iris registration (WF-LASIK), femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), and small incision lenticule extraction (SMILE).Methods. In a prospective study, 82 eyes underwent LASIK, 119 eyes underwent WF-LASIK, 88 eyes underwent FS-LASIK, and 170 eyes underwent SMILE surgery. HOAs were measured with Pentacam device preoperatively and 6 months after surgery. The aberrations were described as Zernike polynomials, and analysis focused on total HOAs, spherical aberration (SA), horizontal coma, and vertical coma over 6 mm diameter central corneal zone.Results. Six months postoperatively, all procedures result in increase of anterior corneal total HOAs and SA. There were no significant differences in the induced HOAs between LASIK and FS-LASIK, while SMILE induced fewer total HOAs and SA compared with LASIK and FS-LASIK. Similarly, WF-LASIK also induced less total HOAs than LASIK and FS-LASIK, but only fewer SA than FS-LASIK (P<0.05). No significant difference could be detected in the induced total HOAs and SA between SMILE and WF-LASIK, whereas SMILE induced more horizontal coma and vertical coma compared with WF-LASIK (P<0.05).Conclusion. FS-LASIK and LASIK induced comparable anterior corneal HOAs. Compared to LASIK and FS-LASIK, both SMILE and WF-LASIK showed advantages in inducing less total HOAs. In addition, SMILE also possesses better ability to reduce the induction of SA in comparison with LASIK and FS-LASIK. However, SMILE induced more horizontal coma and vertical coma compared with WF-LASIK, indicating that the centration of SMILE procedure is probably less precise than WF-LASIK.

Sign in / Sign up

Export Citation Format

Share Document