The purpose of this study is to evaluate the accuracy of the WaveLight FS200 femtosecond laser, as assessed by 1 day and 1 month post-operative optical coherence tomography (OCT) anterior segment corneal measurements compared to pre-operative flap thickness target.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
60
Excimer EX500 and Femtosecond FS200 lasers (Wavelight® Refractive Suite) used during LASIK surgery for corneal flap creation and corneal ablation
Surgical procedure for treating refractive error based on corneal reshaping
The Difference Between Achieved Flap Thickness at Day 1 Postoperative as Assessed by OCT and Expected Flap Thickness as Determined Pre-operatively
The expected flap thickness as determined pre-operatively was subtracted from the achieved flap thickness at Day 1 postoperative as assessed by optical coherence tomography (ie, an imaging method using light to capture three-dimensional images). Accuracy of flap creation was defined as an achieved thickness within 10 microns of expected thickness.
Time frame: Day 1 Postoperative
Incidence of Development of Opaque Bubble Layer (OBL)
OBL (the collection of gas bubbles during corneal flap creation) was assessed by digital photo analysis of the area covered by the flap and is reported as the percentage of participants with opaque bubble layer development during femtosecond flap creation.
Time frame: Operation/Surgery (Day 1)
Extent of Opaque Bubble Layer (OBL) Within the Femtosecond Flap
The extent of OBL was assessed by digital photo analysis of the area covered by the flap and is reported as the percentage of flap with opaque bubble layer development during femtosecond flap creation.
Time frame: Operation/Surgery (Day 1)
The Difference Between Achieved Flap Thickness at Month 1 Post-operative as Assessed by OCT and Expected Flap Thickness as Determined Preoperatively
The expected flap thickness as determined pre-operatively subtracted from the achieved flap thickness at Month 1 postoperative as assessed by optical coherence tomography (ie, an imaging method using light to capture three-dimensional images). Accuracy of flap creation was defined as an achieved thickness within 10 microns of expected thickness.
Time frame: Month 1 Postoperative
Uncorrected Visual Acuity (UCVA)
Visual acuity (VA) without spectacles or other visual corrective devices, was performed with an Early Treatment Diabetic Retinopathy Study (ETDRS) chart set at a distance of 4 meters. UCVA was measured in logMAR (logarithm of the minimum angle of resolution), with 0.00 logMAR corresponding to 20/20 Snellen. A lower logMAR value indicates better visual acuity.
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Time frame: Baseline/Screening (Day 0), Day 1 Postoperative, Month 1 Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Best Corrected Visual Acuity (BCVA)
VA with the subjects's best spectacles or other visual corrective devices, was performed with an ETDRS chart set at a distance of 4 meters. BCVA was measured in logMAR (logarithm of the minimum angle of resolution), with 0.00 logMAR corresponding to 20/20 Snellen. A lower logMAR value indicates better visual acuity.
Time frame: Baseline/Screening (Day 0), Day 1 Postoperative, Month 1 Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Manifest Refraction (Sphere)
A series of test lenses in graded powers was used to determine which corrective lenses provided the sharpest, clearest vision. Manifest refraction is measured in diopters. Each eye contributed individually to the analysis.
Time frame: Baseline/Screening (Day 0), Day 1 Postoperative, Month 1 Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Manifest Refraction (Cylinder)
A series of test lenses in graded powers was used to determine which corrective lenses provided the sharpest, clearest vision. Manifest refraction is measured in diopters. Each eye contributed individually to the analysis.
Time frame: Baseline/Screening (Day 0), Month 1 Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Mean Contrast Sensitivity (CS)
Contrast sensitivity (ie, the ability to detect slight changes in luminance before they become indistinguishable) was assessed binocularly with distance manifest correction in place and uncorrected. Contrast sensitivity was assessed at spatial frequencies of 3, 6, 12, and 18 cycles per degree (cpd), where 3.0 cpd = A, 6.0 cpd = B, 12.0 cpd = C, and 18.0 cpd = D. Raw scores were log transformed. A higher numeric value represents better contrast sensitivity. Both eyes contributed to the analysis.
Time frame: Baseline/Screening (Day 0), Month 1 Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Corneal Flap Diameter as Assessed by Ocular Coherence Tomography (OCT)
The diameter of the corneal flap was assessed by OCT (ie. an imaging method using light to capture three-dimensional images). Corneal flap is measured in millimeters.
Time frame: Operation/Surgery (Day 1), Day 1 Postoperative, Month 1 Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Wavefront Aberrometry
Wavefront aberrations (optical imperfections of the eye that prevent light from focusing perfectly on the retina, resulting in defects in the visual image) were measured using a commercially available system. Higher order aberrations (i.e., spherical aberrations, coma, and trefoil) are defined as optical imperfections which cannot be corrected by any reliable means of present technology.
Time frame: Operation/Surgery (Day 1), Month 1 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Mean Response: "Rate Your Vision, Over the Past 4 Weeks, With NO Glasses or Contact Lenses"
As recorded by the subject on the the Refractive Status and Vision Profile (RSVP), a self-reported questionnaire used to measure vision-related health status in persons with refractive error, on a scale from 0 (completely blind) to 10 (perfect vision).
Time frame: Baseline/Screening (Day 0), Month 1 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Percent Response to "Have Always Worn Glasses or Contact Lenses in the Past 4 Weeks"
As recorded by the subject on the the Refractive Status and Vision Profile (RSVP), a self-reported questionnaire used to measure vision-related health status in persons with refractive error.
Time frame: Baseline/Screening (Day 0), Month 1 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Percent Response by Category: "I Worry About my Vision"
As recorded by the subject on the RSVP questionnaire
Time frame: Baseline/Screening (Day 0), Month 1 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Percent Response by Category: "My Vision is a Concern in my Daily Life"
As recorded by the subject on the RSVP questionnaire
Time frame: Baseline/Screening (Day 0), Month 1 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Percent Response by Category: "Driving at Night"
As recorded by the subject on the RSVP questionnaire, where 0 is "Not applicable", 1 is "No difficulty at all", 2 is "A little difficulty", 3 is "Moderate difficulty", 4 is "Severe difficulty" and 5 is "So much difficulty that I did not do the activity with this alternative".
Time frame: Baseline/Screening (Day 0), Month 1 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Corneal Curvature as Measured by Keratometry
Corneal curvature as assessed by a commercially available system and measured in diopters.
Time frame: Baseline/Screening (Day 0), 1 Month Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Flap Creation Time as Documented in the Log Files
The time to create the flap with FS200 Femtosecond Flap Creation System, measured in seconds.
Time frame: Operation/Surgery (Day 1)
Corneal Topography: Q-value
The Q-value (a measure of corneal asphericity) was assessed using a commercially available system. The Q-values are negative (-1 \< Q \< 0) for prolate corneas, in which the central curvature is steeper than the peripheral curvature, and positive (Q \> 0) for oblate corneas, in which the central curvature is flatter than the peripheral curvature.
Time frame: Day 1 Postoperative, Month 1 Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Corneal Topography: Anterior Chamber (AC) Volume
The AC volume (a measure of the shallowness of the anterior chamber) was assessed using a commercially available system. The lower the chamber volume, the more shallow the anterior chamber or the chamber angle.
Time frame: Day 1 Postoperative, Month 1 Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Corneal Topography: Anterior Chamber (AC) Depth
The AC depth (axial distance between the anterior surface of the cornea and the anterior surface of the lens) was assessed using a commercially available system. A higher value represents a longer distance.
Time frame: Day 1 Postoperative, Month 1 Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative
Corneal Topography: Angles
The angles (angular measurement of the space between the iris and the lens) were assessed using a commercially available system. The higher the value, the bigger the space.
Time frame: Day 1 Postoperative, Month 1 Postoperative, Month 3 Postoperative, Month 6 Postoperative, Month 12 Postoperative