scholarly journals Comparison of corneal biomechanics after myopic small-incision lenticule extraction compared to LASIK: an ex vivo study

2018 ◽  
Vol Volume 12 ◽  
pp. 237-245 ◽  
Author(s):  
Anastasios John Kanellopoulos
Keyword(s):  
Ex Vivo ◽  
Corneal Biomechanics ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Lenticule Extraction ◽  
Ex Vivo Study

New parameters for evaluating corneal biomechanics and intraocular pressure after small-incision lenticule extraction by Scheimpflug-based dynamic tonometry

2017 ◽  
Vol 43 (6) ◽  
pp. 803-811 ◽  
Author(s):  
Joaquín Fernández ◽  
Manuel Rodríguez-Vallejo ◽  
Javier Martínez ◽  
Ana Tauste ◽  
Patrizia Salvestrini ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Corneal Biomechanics ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Lenticule Extraction

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

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.

scholarly journals Review of Corneal Biomechanical Properties Following LASIK and SMILE for Myopia and Myopic Astigmatism

2018 ◽  
Vol 12 (1) ◽  
pp. 164-174 ◽  
Author(s):  
Iben Bach Damgaard ◽  
Mohamed Reffat ◽  
Jesper Hjortdal
Keyword(s):  
Femtosecond Laser ◽  
Ex Vivo ◽  
Biomechanical Properties ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Lenticule Extraction ◽  
A Minor ◽  
Corneal Biomechanical Properties

Worldwide, femtosecond Laser AssistedIn-situKeratomileusis (LASIK) is a well known and commonly used refractive technique, although Small Incision Lenticule Extraction (SMILE) has become increasingly popular since it was introduced in 2011. In LASIK, a corneal flap is cut with a microkeratome or femtosecond laser, followed by thinning of the stromal bed with excimer laser ablation. In SMILE, a minor intrastromal lenticule is cut with a femtosecond laser and subsequently removed through a small incision, leaving the anterior and strongest part of the cornea almost intact. Both LASIK and SMILE require cutting of corneal lamellae that may reduce the biomechanical stability of the cornea, with the potential risk of corneal iatrogenic ectasia as a severe complication. However, SMILE preserves the anterior corneal integrity and may, in theory, better preserve the corneal biomechanical strength than LASIK after surgery.A review aimed to examine the current literature that describes and compares the corneal biomechanical properties after Laser AssistedIn-situKeratomileusis (LASIK) and Small Incision Lenticule Extraction (SMILE). A comprehensive search was performed in Pubmed.gov using the following search queries: Corneal biomechanical properties, corneal biomechanics, ocular response analyser, ocular response analyzer, ORA,ex vivo, in vitro, Corvis, Corvis ST, LASIK, and SMILE.

Comparison of corneal biomechanics after microincision lenticule extraction and small incision lenticule extraction

2016 ◽  
Vol 101 (5) ◽  
pp. 650-654 ◽  
Author(s):  
Zhiqing Wu ◽  
Yan Wang ◽  
Jiamei Zhang ◽  
Tommy C Y Chan ◽  
Alex L K Ng ◽  
...  
Keyword(s):  
Corneal Biomechanics ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Lenticule Extraction

scholarly journals The Correlation Analysis between Corneal Biomechanical Properties and the Surgically Induced Corneal High-Order Aberrations after Small Incision Lenticule Extraction and Femtosecond Laser In Situ Keratomileusis

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Wenjing Wu ◽  
Yan Wang
Keyword(s):  
Femtosecond Laser ◽  
High Order ◽  
Corneal Biomechanics ◽  
Laser In Situ Keratomileusis ◽  
Small Incision Lenticule Extraction ◽  
Small Incision ◽  
Lenticule Extraction ◽  
Surgically Induced ◽  
High Order Aberrations

Background. To investigate the correlation between corneal biomechanics and the surgically induced corneal high-order aberrations (HOAs) after small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK).Methods. A total of 150 right myopic eyes that underwent SMILE or FS-LASIK surgery were included in this retrospective study, 75 eyes in each group. The corneal hysteresis (CH) and the corneal resistance factor (CRF) with the corneal HOAs of the anterior, posterior, and total cornea were assessed preoperatively and three months postoperatively. Multivariate linear regression was applied to determine the correlations.Results. The preoperative CRF was significantly correlated with the induced 3rd–6th-order HOAs and spherical aberration of the anterior surface and the total cornea after SMILE and FS-LASIK surgeries (P<0.05), postoperatively. The CRF was significantly correlated with the induced vertical coma of the anterior and posterior surfaces and the total cornea after SMILE surgery (P<0.05). There was a significant correlation between the CRF and the induced posterior corneal horizontal coma after FS-LASIK surgery (P=0.013).Conclusions. The corneal biomechanics affect the surgically induced corneal HOAs after SMILE and FS-LASIK surgery, which may be meaningful for screening the patients preoperatively and optimizing the visual qualities postoperatively.

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

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
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.

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

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ting Liu ◽  
Ting Yu ◽  
Lina Liu ◽  
Kaijian Chen ◽  
Ji Bai
Keyword(s):  
Visual Acuity ◽  
Contrast Sensitivity ◽  
Spherical Aberration ◽  
Corneal Thickness ◽  
Cutoff Frequency ◽  
Corneal Biomechanics ◽  
Controlled Study ◽  
Small Incision Lenticule Extraction ◽  
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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