COMPARISON OF AUTOMATED VISUAL FIELD AND OPTIC NERVE FIBER POLARIMETRY
(GDX) IN GLAUCOMATOUS EYES: OVERALL AND TOPOGRAPHIC CORRELATIONS
Purpose: To evaluate the correlation between Humphrey 24-2 Automated
visual field and nerve fiber thickness analysis by scanning laser polarimetry
(GDx).
Methods: 50 glaucomatous eyes underwent visual field and GDx within 2
months. All visual field were evaluated by means of the CIGTS scoring system.
11 GDx parameters were correlated with visual field indices: MD (mean defect),
PSD (pattern standard deviation), total CIGTS score, superior CIGTS score,
inferior CIGTS score.
Results: Visual field mean defect correlated significantly with “the
number”(r = -0,42) and with modulation (r =0,45) and ratio (r = 0,452)
parameters, while feeble correlation existed with thickness parameters. The
same trend was detected for total CIGTS score. The topographic correlation
between superior hemifield score was good with GDx’s inferior maximum (r =
-0,39) and inferior average (r = 0,392) (both absolute thickness parameters)
whereas inferior hemifield score correlated very well with superior ratio (r =
0,492) and superior/nasal ratio (r = 0,491). No statistically significant correlation was found betwwen PSD and
any of GDx parameters.
Conclusion:GDX parameters that better correlate with MD and total CIGTS
score are the modulation and ratio: they seem to be more useful in the
diagnosis of glaucoma than absolute thickness parameters due to the high
variability of normal RNFL thickness and to the wide overlapping of normal and
glaucomatous values. The topographic correlation was strong for inferior
hemifield and superior fibers. Absolute thickness values are more useful in
follow-up than in diagnosis of glaucoma.