Purpose: A study was
conducted to determine the ability of scanning laser polarimetry using the
Nerve Fiber Analyzer GDx (Laser Diagnostic Technologies, San Diego, CA) to
detect progression or stability in glaucoma patients or suspects as determined
by visual field testing with automated perimetry. Methods: Masked
GDx printouts and visual field examinations matched by date from patients in a
glaucoma practice who underwent a minimum of three GDx examinations over a
minimum of two years were reviewed separately by a single reviewer, looking for
worsening from the first examination to the last. Results were tabulated and tested for statistical
significance with McNamar's test.
Results: A total of 91 eyes
of 46 patients (43 primary open angle glaucoma, 37 ocular hypertension, 7
suspicious optic nerves, and 4 normal) were evaluated. 63 eyes showed no change on either
test, 8 showed worsening on both, 18 showed apparent worsening on the GDx only,
and 2 showed worsening on the visual field only (p <0.001). The two tests were in agreement in 78%
of cases. Conclusions: Scanning laser polarimetry is a promising technique
for assessing the retinal nerve fiber layer in vivo, and parallels the visual
field for detecting change or stability over time in the vast majority of
cases. It is possible that it is
more sensitive to change, but longer follow up is needed to see if change
suggested by the GDx is eventually reflected in the visual field.