WaveLight® Refractive Flap Accuracy Study

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

As recorded by the subject on the RSVP questionnaire

As recorded by the subject on the RSVP questionnaire

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".

Corneal curvature as assessed by a commercially available system and measured in diopters.

The time to create the flap with FS200 Femtosecond Flap Creation System, measured in seconds.

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.

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.

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.

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.