Aberration-Free Refraction Correction
Recruitment status was: Recruiting
|Study Design:||Observational Model: Defined Population
Primary Purpose: Screening
Time Perspective: Cross-Sectional
Time Perspective: Retrospective/Prospective
|Official Title:||National Taiwan University Hospital|
|Study Start Date:||June 2005|
|Estimated Study Completion Date:||July 2008|
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 patient’s 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 patient’s 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 cornea’s 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.
Please refer to this study by its ClinicalTrials.gov identifier: NCT00172913
|National Taiwan University Hospital|
|Principal Investigator:||I-Jong Wang, MD,PHD||National Taiwan University Hospiyal|