Related Experiment Video
Updated: Jul 7, 2026

Correction of Presbyopia by Monocular Bi-Aspheric Ablation Profile
Published on: September 20, 2024
A defined change of polarization axis is detected by variable corneal compensation of the GDxVCC
Eckart Schmidt1, Andreas G Boehm, Lutz E Pillunat
1Department of Ophthalmology, University of Dresden, Germany. Eckart.Schmidt@uniklinikum-dresden.de
Purpose:
The aim of the study was to examine whether a defined change of polarization axis (PA) is detected by the variable cornea compensation (VCC) of the GDxVCC. The idea behind was to induce a change of PA by a rotation of the eye and to determine whether the rotation affects the magnitude of retardation and retinal nerve fiber layer measurements.
Methods:
Fifteen normal eyes were examined with the GDxVCC. First scans (cornea and optic nerve head) of the right eye in regular position (0 degree) were performed. These scans are recognized and saved regularly as a right eye by the instrument. Then a second scan set of the same eye was taken: the subjects turned their head upside-down (180 degrees). These scans were recognized and saved as a left eye. For each scan, the instrument calculates the polarization parameter axis and magnitude.
Results:
The difference of magnitude was 4.3+/-3.7 nm (0 to 12 nm) and difference of axis was 3.5+/-2.4 degrees (0.1 to 8.1 degrees). There were no significant differences in all measured parameters between the "normal" and the turned eye (all P>0.2; paired t tests).
Discussion:
A defined change of PA was detected by the VCC of the GDx and the instrument was able to reproduce the polarization parameters of the anterior segment and retinal nerve fiber layer parameters of the same eye in 2 different positions with adequate accuracy.
Related Concept Videos
Group Polarization
Potential Due to a Polarized Object
Dielectric Polarization in a Capacitor
Angle Closure Glaucoma: Treatment
Phase Contrast and Differential Interference Contrast Microscopy
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...
Open Angle Glaucoma: Treatment
Drugs such as carbonic anhydrase inhibitors, α2- and...
