Purpose: It is
generally assumed that patients can lose 30-50% of their retinal Nerve Fiber
Layer (NFL) tissue, before the first glaucomatous abnormalities appear on
standard visual field testing. The GDx (Laser Diagnostic Technologies, San
Diego, CA) is a scanning laser polarimeter that assesses NFL thickness in vivo.
Therefore, the GDx might be capable of detecting so-called pre-perimetric
abnormalities. We present four cases illustrating that this is in fact true.
Methods: 400
patients with ocular hypertension have been measured routinely twice a year
with the GDx and the Humphrey Field Analyzer (24-2 white-on-white full
threshold test strategy). At baseline, several patients had glaucomatous GDx
scans; all patients had reproducible, normal visual fields.
Results:
Case Window
1 (months) Window
2 (months)
#1 9 21
#2 13 13
#3 12 18
#4 19 19
The table shows the
time interval in months between the first abnormal GDx, and the first abnormal
visual field (window1). Window 2 is the time interval in months between the
first (reproducible) abnormal GDx, and the first (reproducible) abnormal visual
field. We will present consecutive GDx and HFA exams of all four cases, as well
as some guidelines for detecting early abnormalities with the GDx.
Conclusions: In the
four cases we presented, the GDx was capable of detecting glaucomatous
abnormalities before they appeared on the visual fields. The window between the
first (reproducible) abnormal GDx, and the first (reproducible) abnormal visual
field could be as wide as 21 months.
Proprietary
Interest: F