Corneal Cap Thickness and Its Effect on Visual Acuity and Corneal Biomechanics in Eyes Undergoing Small Incision Lenticule Extraction

Purpose. To evaluate the effect of corneal cap thickness on visual acuity and corneal biomechanics in small incision lenticule extraction (SMILE) for the treatment of myopia. Methods. Forty eyes of 20 patients undergoing SMILE for the treatment of myopia were enrolled in this prospective controlled study. The patients with 510 μm–560 μm central corneal thickness (CCT) and a refractive spherical equivalent of −3.00 D to −8.00 D were included. It was designed randomly to undergo SMILE with a 110 μm cap thickness in one eye and 150 μm cap thickness in the other. Ophthalmic examinations included best-corrected and uncorrected visual acuity (UCVA); refractive status, contrast sensitivity, and objective visual quality were evaluated at 2 h, 4 h, and 24 h postoperatively; while at 3 months after the procedure, corrected intraocular pressure (IOP), higher order aberrations (HOAs), and morphologic modifications of corneal architecture of both eyes were assessed. Results. Compared with the 150 μm group, the incidence of OBL was significantly higher in the 110 μm cap thickness group (P=0.004), and UCVA, Strehl ratio (SR), objective scatter index (OSI), modulation transfer function (MTF) cutoff frequency, and photopic and scotopic contrast sensitivity at medium spatial frequency were all significantly better in 110 μm group at 2 h and 24 h postoperatively (P<0.05). Corneal spherical aberration and corrected IOP by Corvis ST were significantly higher in the 110 μm group at 3 months postoperatively (P<0.05). No statistically significant differences were found in manifest refraction, UCVA, SR, OSI, MTF cutoff, and mesopic and photopic contrast sensitivity at low frequency, photopic contrast sensitivity at high frequency, endothelial density, corneal coma, and total HOAs at 3 months after the procedure. No visual decline was found in the patients in this study. Conclusions. Both 110 μm and 150 μm cap thickness in SMILE were safe and effective for treatment of myopia. A 110 μm cap thickness demonstrated better visual outcomes during early and late postoperative periods with higher corneal spherical aberration and corrected IOP at 3 months postoperatively. This trial is registered with ChiCTR-IOR-17013369.

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

10.21203/rs.2.15558/v1 ◽

2019 ◽

Author(s):

Fei Xia ◽

Yang Shen ◽

Tian Han ◽

Jing Zhao ◽

Hai-Peng Xu ◽

...

Keyword(s):

Visual Acuity ◽

Spherical Aberration ◽

Case Series ◽

Final Visit ◽

Small Incision Lenticule Extraction ◽

Wavefront Aberrations ◽

Distance Visual Acuity ◽

Small Incision ◽

Uncorrected Distance Visual Acuity ◽

Lenticule Extraction

Abstract Background To investigate the long-term corneal stability and wavefront aberrations after small incision lenticule extraction (SMILE) for moderate and high myopia.Methods Prospective, non-consecutive case series. A total of 26 patients (42 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 topography.Results All surgeries were executed without any complications. At the final visit, a UDVA of 20/20 or better was achieved in 42 eyes (100%), 21 eyes (50%) exhibited no change in CDVA. 15 eyes (36%) gained one line, 6 eyes (14%) gained two lines, and no eyes lost CDVA lines. 93% and 100% of eyes 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 (KMF) were significantly increased 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 horizontal coma, trefoil and spherical aberration between pre- and post-SMILE surgery (all P>0.05).Conclusions SMILE is an effective, safe and stable procedure for myopia correction, with relatively constant corneal stability and wavefront aberrations.

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Intraocular pressure changes and corneal biomechanics after hyperopic small-incision lenticule extraction

10.21203/rs.2.18089/v1 ◽

2019 ◽

Author(s):

Dan Fu ◽

Meiyan Li ◽

Michael C. Knorz ◽

Shengsheng Wei ◽

Jianmin Shang ◽

...

Keyword(s):

Intraocular Pressure ◽

Mixed Model ◽

Linear Mixed Model ◽

Corneal Thickness ◽

Corneal Biomechanics ◽

Ocular Response Analyzer ◽

Small Incision Lenticule Extraction ◽

Corvis St ◽

Small Incision ◽

Lenticule Extraction

Abstract Background: To compare intraocular pressure (IOP) measurements by a dynamic Scheimpflug analyzer (Corvis ST), a non-contact tonometer, and the ocular response analyzer following hyperopic small-incision lenticule extraction (SMILE).Methods: Thirteen patients underwent hyperopic SMILE in one eye each were prospectively enrolled. IOP and corneal biomechanical parameters were measured preoperatively and 1 week, 1 month, and 3 months after surgery with a non-contact tonometer (IOPNCT), Corvis ST (biomechanical corrected IOP, bIOP), and the ocular response analyzer (Goldmann-correlated intraocular pressure [IOPg], cornea compensated IOP [IOPcc]). A linear mixed model was used to compare IOP and biomechanical values among the methods at each time point.Results: IOPNCT, IOPg, and IOPcc dropped significantly after surgery, with the amplitude being 3.15±0.48 mmHg, 5.49±0.94 mmHg, and 4.34±0.97 mmHg, respectively, at the last visit. IOPNCT decreased by 0.11±0.06 mmHg per µm of removed central corneal thickness. bIOP did not change significantly after surgery. Before surgery, no difference was found among the measurements (P> 0.05). After surgery, IOPNCT and bIOP were higher than IOPg and IOPcc. bIOP is independent of cornea thickness at the last visit, while correlated significantly with corneal biomechanics as other three IOP values did.Conclusion: bIOP (biomechanical corrected IOP as measured with the Corvis ST) seems to be an accurate parameter to measure IOP after hyperopic SMILE.

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Corneal Spherical Aberration and Corneal Asphericity after Small Incision Lenticule Extraction and Femtosecond Laser-Assisted LASIK

Journal of Ophthalmology ◽

10.1155/2017/4921090 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Hui Zhang ◽

Yan Wang ◽

Hua Li

Keyword(s):

Visual Acuity ◽

Femtosecond Laser ◽

Spherical Aberration ◽

Laser In Situ Keratomileusis ◽

Anterior Surface ◽

Small Incision Lenticule Extraction ◽

Distance Visual Acuity ◽

Small Incision ◽

Corneal Asphericity ◽

Lenticule Extraction

Purpose. To investigate corneal spherical aberration and corneal asphericity after small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). Methods. This study enrolled 70 patients having SMILE and 64 subjects receiving FS-LASIK. The preoperative spherical equivalent (SE) was −5.83 ± 1.23 diopters (D) and −6.20 ± 1.52 D, respectively. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), SE, corneal spherical aberration, and asphericity over the 6.0 mm cornea were evaluated preoperatively and postoperatively. Results. At 6 months, the UDVA, CDVA, and SE were −0.12 ± 0.11, −0.05 ± 0.05, and −0.16 ± 0.19 D in SMILE and −0.10 ± 0.06, −0.03 ± 0.06, and −0.08 ± 0.25 D in FS-LASIK. There was no difference between groups in the postoperative UDVA, CDVA, or SE (P>0.05). SMILE showed lower inductions of spherical aberration along the anterior surface and the total cornea and less increases in corneal asphericity of the anterior surface postoperatively than FS-LASIK (P<0.01). There were significant correlations between the changes in spherical aberration and corneal asphericity (P<0.001). Conclusions. SMILE and FS-LASIK exhibited excellent visual results and refractive outcomes. SMILE induced less increase in corneal spherical aberration and better preserved the corneal asphericity of the anterior corneal surface than FS-LASIK. Corneal asphericity changes contributed to the corneal spherical aberration changes following SMILE and FS-LASIK.

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

Journal of Ophthalmology ◽

10.1155/2020/3825864 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Fei Xia ◽

Yang Shen ◽

Tian Han ◽

Jing Zhao ◽

Haipeng Xu ◽

...

Keyword(s):

Visual Acuity ◽

High Myopia ◽

Spherical Aberration ◽

Final Visit ◽

Small Incision Lenticule Extraction ◽

Wavefront Aberrations ◽

Distance Visual Acuity ◽

Small Incision ◽

Lenticule Extraction ◽

Corneal Tomography

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.

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Evaluation of Corneal Biomechanical Properties Modification after Small Incision Lenticule Extraction Using Scheimpflug-Based Noncontact Tonometer

BioMed Research International ◽

10.1155/2014/290619 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 16

Author(s):

Leonardo Mastropasqua ◽

Roberta Calienno ◽

Manuela Lanzini ◽

Martina Colasante ◽

Alessandra Mastropasqua ◽

...

Keyword(s):

Intraocular Pressure ◽

Central Corneal Thickness ◽

Corneal Thickness ◽

Biomechanical Properties ◽

Corneal Biomechanics ◽

Small Incision Lenticule Extraction ◽

Small Incision ◽

Lenticule Extraction ◽

Noncontact Tonometer ◽

Corneal Biomechanical Properties

Purpose.To quantify the effect of small incision lenticule extraction (SMILE) on the corneal biomechanics using Scheimpflug noncontact tonometer (Corvis ST).Methods.Twenty eyes of twenty patients, evaluated as eligible for surgery, with high myopia and/or moderate myopic astigmatism, underwent small incision lenticule extraction (SMILE). All patients underwent Corvis ST preoperatively and postoperatively after 1 week, and 1 and 3 months to observe alterations of corneal biomechanical properties. The main outcome measures were Deformation Amplitude, 1st-AT, and 2nd-AT. The relationship between the amount of stroma removed and the percentage variation of the measured parameters from baseline was evaluated with generalized linear model from each time point. For completeness also intraocular pressure (IOP), central corneal thickness (CCT), and their variations after surgery were evaluated.Results.The ratio between the amount of removed refractive error and, respectively, changes of Deformation Amplitude, 1st-AT, and 2nd-AT were significantly modified at the 1st week after surgery(P=0.005; P=0.001; P=0.024). At 1 and 3 months these values did not show statistically significant alterations. Intraocular pressure and central corneal thickness showed statistically significant changes during follow-up.Conclusions.No significant modifications in biomechanical properties were observed after SMILE so this procedure could induce only minimal transient alterations of corneal biomechanics.

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Effect of corneal stromal pocket irrigation in small-incision lenticule extraction

Eye ◽

10.1038/s41433-020-0840-1 ◽

2020 ◽

Vol 34 (12) ◽

pp. 2328-2335 ◽

Cited By ~ 1

Author(s):

Han Wang ◽

Hui Ding ◽

Bo-wen Ouyang ◽

Zhenduo Yang ◽

Tan Zhong ◽

...

Keyword(s):

Visual Acuity ◽

Cell Number ◽

Controlled Study ◽

Small Incision Lenticule Extraction ◽

Small Incision ◽

Uncorrected Distance Visual Acuity ◽

Significant Difference ◽

Lenticule Extraction ◽

Prospective Controlled Study ◽

Anterior Oct

Abstract Objectives To investigate the effect of corneal stromal pocket irrigation after small-incision lenticule extraction (SMILE) on visual acuity, intraocular pressure (IOP), corneal parameters and complications after surgery. Methods A total of 242 eyes of 121 patients undergoing SMILE were enrolled in this prospective controlled study, and it was designed for one eye to randomly undergo SMILE with balanced salt solution irrigation of the corneal stromal pocket, while the other eye was not. The uncorrected distance visual acuity (UDVA) and slit lamp examination were recorded at 1 hour, 1 day, 1 week, and 1 month. Postoperative corneal density, corneal biomechanical, corneal endothelial cell number, and anterior OCT images were compared at 1 day, 1 week, and 1 month. Results Compared with the nonirrigation group, the irrigation group showed significantly higher UDVA at 1 day postoperatively (P < 0.05), but there was no significant difference during the rest of the postoperative period (1 hour, 1 week, and 1 month). In addition, no significant differences were found in IOP, corneal density, corneal biomechanics, corneal endothelial cells, and corneal morphology. No visual decline or severe postoperative complications were found in the patients in this study. Conclusions Interlamellar irrigation did not affect IOP, corneal parameters, morphology, complications, or UDVA at 1 hour, 1 week, and 1 month after the operation, but it may promote UDVA 1 day after the operation.

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Impact of extreme (flat and steep) keratometry on the safety and efficacy of small incision lenticule extraction (SMILE)

Scientific Reports ◽

10.1038/s41598-021-97375-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Nikolaus Luft ◽

Jakob Siedlecki ◽

Franziska Reinking ◽

Wolfgang J. Mayer ◽

Benedikt Schworm ◽

...

Keyword(s):

Visual Acuity ◽

Spherical Aberration ◽

Spherical Equivalent ◽

Small Incision Lenticule Extraction ◽

Safety And Efficacy ◽

Distance Visual Acuity ◽

Small Incision ◽

Department Of Ophthalmology ◽

Corrected Distance Visual Acuity ◽

Lenticule Extraction

AbstractLittle is known about the connection between preoperative keratometry and postoperative results of myopic small-incision lenticule extraction (SMILE). To determine the influence of extreme (flat and steep) corneal keratometry on the safety and efficacy of SMILE, the databases of the Department of Ophthalmology, Ludwig-Maximilians-University Munich, Germany, and SMILE Eyes Linz, Austria, were screened for patients with steep and flat keratometry who had undergone SMILE. In this cross-sectional matched comparative cohort study, eyes with markedly flat (< 42.0 diopters; D) or steep (≥ 47.0D) preoperative corneal keratometry were matched to a cohort of eyes with regular keratometry (42.0–46.9D) by preoperative manifest refractive spherical equivalent and cylinder, age, corrected distance visual acuity and surgical SMILE parameters. The standardized graphs and terms for refractive surgery results were applied to compare the three groups. Changes in higher order aberrations (HOAs) were evaluated on Scheimpflug imaging. In total, 63 eyes (21 each) of 54 patients with a mean refractive spherical equivalent of − 5.21 ± 1.59 D were followed up for a mean of 9.2 ± 6.1 (minimum ≥ 3) months. Mean baseline keratometry was 41.3 ± 0.7D (flat), 45.5 ± 1.0D (regular) and 47.7 ± 0.6D (steep) (p < 0.0001). Compared to the regular group, the flat and the steep cornea group resulted in a non-inferior percentage of eyes within ± 0.50 D of target refraction (p = 0.20), uncorrected distance visual acuity (p = 0.95) and corrected distance visual acuity (p = 0.20). Flat corneas however experienced a stronger induction of spherical aberration (SA) compared to the steep group (p = 0.0005). In conclusion, non-inferior outcomes of SMILE can also be expected in eyes with steep (≥ 47D) or flat (< 42D) preoperative keratometry, while SMILE however induces more SA in eyes with a flat keratometry.

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Intraocular pressure changes and corneal biomechanics after hyperopic small-incision lenticule extraction

10.21203/rs.2.18089/v2 ◽

2020 ◽

Author(s):

Dan Fu ◽

Meiyan Li ◽

Michael C. Knorz ◽

Shengsheng Wei ◽

Jianmin Shang ◽

...

Keyword(s):

Intraocular Pressure ◽

Linear Mixed Model ◽

Corneal Thickness ◽

Corneal Biomechanics ◽

Ocular Response Analyzer ◽

Small Incision Lenticule Extraction ◽

Corvis St ◽

Small Incision ◽

Lenticule Extraction

Abstract Background: We aimed to compare the intraocular pressure (IOP) measurements by a dynamic Scheimpflug analyzer (Corvis ST), a non-contact tonometer, and an ocular response analyzer after hyperopic small-incision lenticule extraction (SMILE).Methods: Thirteen patients who underwent hyperopic SMILE in one eye were enrolled prospectively. IOP and corneal biomechanical parameters were measured preoperatively and at 1 week, 1 month, and 3 months postoperatively with a non-contact tonometer (IOPNCT), Corvis ST (biomechanical corrected IOP and biomechanical corrected IOP measured with Corvis ST [bIOP]), and an ocular response analyzer (Goldmann-correlated intraocular pressure [IOPg] and cornea compensated IOP [IOPcc]). A linear mixed model was used to compare the IOP and biomechanical values among methods at each time point.Results: IOPNCT, IOPg, and IOPcc dropped significantly after surgery, with the amplitude being 3.15±0.48 mmHg, 5.49±0.94 mmHg, and 4.34±0.97 mmHg, respectively, at the last follow-up visit. IOPNCT decreased by 0.11±0.06 mmHg per µm of excised central corneal thickness. bIOP did not change significantly after surgery. Preoperatively, no difference was found among the measurements (P> 0.05). Postoperatively, IOPNCT and bIOP were higher than IOPg and IOPcc. bIOP was independent of cornea thickness at last follow-up visit, whereas it correlated significantly with corneal biomechanics similar to the other three IOP values.Conclusion: bIOP is a relative accurate measure of IOP after hyperopic SMILE.

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

Journal of Ophthalmology ◽

10.1155/2016/8702162 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7 ◽

Cited By ~ 5

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.

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