Ignite Creation Date:
2024-05-06 @ 11:43 AM
Last Modification Date:
2024-10-26 @ 12:49 PM
Study NCT ID:
NCT03584555
Status:
COMPLETED
Last Update Posted:
2020-10-19
First Post:
2018-06-19
Brief Title:
Comparison of Clinical Outcomes of Small-incision Lenticule Extraction SMILE Between Different Cap Thickness
Sponsor:
Yonsei University
Organization:
Yonsei University
Study Overview
Official Title:
Comparison of Clinical Outcomes of Small-incision Lenticule Extraction SMILE Between Different Cap Thickness
Status:
COMPLETED
Status Verified Date:
2020-10
Last Known Status:
None
Delayed Posting:
No
If Stopped, Why?:
Not Stopped
Has Expanded Access:
False
If Expanded Access, NCT#:
N/A
Has Expanded Access, NCT# Status:
N/A
Acronym:
None
Brief Summary:
In the past two decades the femtosecond laser FSL technology has been introduced in the corneal refractive surgery filed and brought a remarkable innovation It can make tissue dissection through photodisruption and plasma cavitation Initially the FSL was used predominantly to make a corneal flap when performing laser in situ keratomileusis LASIK which is followed by stromal ablation using excimer laser A new surgical technique called femtosecond lenticule extraction FLEx has been developed that uses only FSL to dissect two interfaces to create refractive lenticule and then remove it which is very similar with LASIK Small incision lenticule extraction SMILE which is the advanced form of all-in-one FSL refractive technique does not make a corneal flap rather make small incision where the separated refractive lenticule is removed through and the upper part of the corneal tissue is called cap Since the clinical outcomes of SMILE were firstly published in 2011 SMILE has been widely used for correction of myopia or myopic astigmatism worldwide SMILE provides excellent visual outcomes and has advantages including a lesser decrease in corneal sensitivity and absence of flap related complications compared to LASIK
Because corneal ectasia after refractive surgery is the one of most terrifying complication corneal biomechanics has been drawn interests to many researchers and clinicians Theoretically SMILE may preserve corneal biomechanics better than LASIK because the anterior stroma which is stiffer than the posterior stroma remains intact in SMILE However there are some controversies because previous studies investigating corneal biomechanics have been reported inconsistent outcomes although SMILE has been reported equal to or better than LASIK Weakening of corneal biomechanics and iatrogenic corneal ectasia have also been reported after SMILE In addition because the tensile strength of cornea gradually decreases as it goes backwards creating deeper refractive lenticule may result in stronger cornea by preserving more of anterior lamellae of the cornea But on the contrary leaving sufficient residual stromal bed has been known to be important in preventing iatrogenic corneal ectasia hence creating thin cap may be effective and desirable Although many researches have been investigated the difference in biomechanical response between SMILE and LASIK there are few studies evaluating the dependence of cap thickness on postoperative biomechanical strength after SMILE El-Massry et al reported that the thicker cap thickness showed higher postoperative corneal hysteresis CH and corneal resistance factor CRF with Ocular Response Analyzer ORA Reichert Ophthalmic Instruments Depew NY which may not be optimal for a clear description of the viscosity and elasticity of the cornea3 however other studies have been presented that there is no significant difference of corneal biomechanics with cap thickness There is no comparative human study using Corvis ST Oculus Wetzlar Germany despite presence of the study using Corvis ST in rabbit eyes Furthermore no prospective study with large number of subjects has been performed to date
Because corneal ectasia after refractive surgery is the one of most terrifying complication corneal biomechanics has been drawn interests to many researchers and clinicians Theoretically SMILE may preserve corneal biomechanics better than LASIK because the anterior stroma which is stiffer than the posterior stroma remains intact in SMILE However there are some controversies because previous studies investigating corneal biomechanics have been reported inconsistent outcomes although SMILE has been reported equal to or better than LASIK Weakening of corneal biomechanics and iatrogenic corneal ectasia have also been reported after SMILE In addition because the tensile strength of cornea gradually decreases as it goes backwards creating deeper refractive lenticule may result in stronger cornea by preserving more of anterior lamellae of the cornea But on the contrary leaving sufficient residual stromal bed has been known to be important in preventing iatrogenic corneal ectasia hence creating thin cap may be effective and desirable Although many researches have been investigated the difference in biomechanical response between SMILE and LASIK there are few studies evaluating the dependence of cap thickness on postoperative biomechanical strength after SMILE El-Massry et al reported that the thicker cap thickness showed higher postoperative corneal hysteresis CH and corneal resistance factor CRF with Ocular Response Analyzer ORA Reichert Ophthalmic Instruments Depew NY which may not be optimal for a clear description of the viscosity and elasticity of the cornea3 however other studies have been presented that there is no significant difference of corneal biomechanics with cap thickness There is no comparative human study using Corvis ST Oculus Wetzlar Germany despite presence of the study using Corvis ST in rabbit eyes Furthermore no prospective study with large number of subjects has been performed to date
Detailed Description:
None
Study Oversight
Has Oversight DMC:
None
Is a FDA Regulated Drug?:
False
Is a FDA Regulated Device?:
False
Is an Unapproved Device?:
None
Is a PPSD?:
None
Is a US Export?:
None
Is an FDA AA801 Violation?:
None