Ignite Creation Date:
2024-05-05 @ 11:54 AM
Last Modification Date:
2024-10-26 @ 9:16 AM
Study NCT ID:
NCT00172913
Status:
UNKNOWN
Last Update Posted:
2005-09-15
First Post:
2005-09-12
Brief Title:
Aberration-Free Refraction Correction
Sponsor:
National Taiwan University Hospital
Organization:
National Taiwan University Hospital
Study Overview
Official Title:
National Taiwan University Hospital
Status:
UNKNOWN
Status Verified Date:
2005-06
Last Known Status:
RECRUITING
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 interest of improving visual quality after LASIK we have designed a multifaceted study to test the theoretical physical biomechanical and functional effects of commercial and independently designed aspherical ablation profiles
Detailed Description:
The quality of an image on the retina is determined by the optical system of the eyeball which is dominated by the refractive contribution of the optically powerful cornea The large difference in refractive index between air and the cornea is the basis for anterior corneal refractive surgery such as Laser in situ Keratomileusis LASIK which reshapes the naturally aspherical cornea to correct a patients vision In addition to correcting refractive errors current spherical LASIK treatments have been shown to increase ocular wavefront aberrations which can reduce visual quality postoperatively Modifications of the corneal-ablation algorithm have been suggested to correct this issue
Until recently most ablation algorithms have relied on the Munnerlyn formula which assumes the anterior corneal surface to be spherical before and after refractive surgery One concept for customized ablation is to apply an ablation during the surgical procedure which has been adapted to the patients own aberration pattern Since custom ablation algorithms are proprietary and we do not know how they consider the role of asphericity
Precisely altering the corneal asphericity after refraction surgery is a complex phenomenon which includes biomechanical effects Thus knowledge of the corneas response to the different aspherical ablation profiles is vital for understanding corneal properties and prediction of surgical outcomes
This study will involve computer simulation of ablation profiles for the respective lasers interferometric analysis of actual ablation profiles on PMMA plates optimization for visual correction functional studies of the short and long term effects of the profiles on in vivo human corneas and quantitative subjective questionnaire and visual tests and objective analysis calculation of retinal image quality metrics and comparison of the effects aspherical ablation profiles on visual quality The completion of the project will lead to objective evaluation of current ablation profiles as well as the development and evaluation of new optimized laser refractive surgery procedures with improved outcomes
Until recently most ablation algorithms have relied on the Munnerlyn formula which assumes the anterior corneal surface to be spherical before and after refractive surgery One concept for customized ablation is to apply an ablation during the surgical procedure which has been adapted to the patients own aberration pattern Since custom ablation algorithms are proprietary and we do not know how they consider the role of asphericity
Precisely altering the corneal asphericity after refraction surgery is a complex phenomenon which includes biomechanical effects Thus knowledge of the corneas response to the different aspherical ablation profiles is vital for understanding corneal properties and prediction of surgical outcomes
This study will involve computer simulation of ablation profiles for the respective lasers interferometric analysis of actual ablation profiles on PMMA plates optimization for visual correction functional studies of the short and long term effects of the profiles on in vivo human corneas and quantitative subjective questionnaire and visual tests and objective analysis calculation of retinal image quality metrics and comparison of the effects aspherical ablation profiles on visual quality The completion of the project will lead to objective evaluation of current ablation profiles as well as the development and evaluation of new optimized laser refractive surgery procedures with improved outcomes
Study Oversight
Has Oversight DMC:
None
Is a FDA Regulated Drug?:
None
Is a FDA Regulated Device?:
None
Is an Unapproved Device?:
None
Is a PPSD?:
None
Is a US Export?:
None
Is an FDA AA801 Violation?:
None