Abstract
Abstract: :
Purpose:To study the relationship between the nerve fiber layer measured with laser polarimetry (GDx) and a new temporal modulation perimetry (Pulsar perimetry) in patients with ocular hypertension. Methods:Pulsar perimetry is a new perimetric procedure which uses stimuli combining spatial resolution (SR) and contrast (C) for early glaucoma evaluation. Pulsar perimeter shows white round stimuli, 5º in diameter, 500 msec long, shaped as a wave decreasing in amplitude, in 66 locations. The stimuli scale combines SR and C in 36src units. A temporal modulation program with pulsing stimuli at 30 Hz in phase-counter-phase oscillations (program T-30W), which theoretically excites large ganglion cells, was used. We studied 28 eyes of 28 patients with ocular hypertension (mean age: 61,82 SD 9,90). Inclusion criteria: visual acuity ≷0.8, refractive defect 3 mm, no ocular surgery or pathologies and no uncontrolled diseases. All had previous perimetric experience. 5 parameters of the Laser Polarimeter (NFA II-GDx version 1.0.04) were studied: mean nerve fiber layer thickness at the superior and inferior quadrants (SQ-IQ), S/N, maximal modulation, mean ellipse thickness and ellipse's modulation. Spearman's correlation coefficient was used to correlate such parameters with Pulsar's mean sensitivity (MS), mean defect (MD) and loss variance (LV). Results:Correlations were as follows: between SQ-IQ and MS, r: 0,133 (p=0,681); with MD, r: 0,161 (p=0,681); and with LV, r:0,035 (p=0,914). Correlation between S/N and MS, r: 0,155 (p=0,431); with MD r: -0,148 (p=0,453); and with LV r: 0,188 (p=0,549). Conclusion:There is a low correlation between laser polarimetry and Pulsar perimetry in patients with ocular hypertension. The fact that the magnocellular pathway (theoretically studied by Pulsar perimetry) is affected in early stages of glaucoma can explain such poor correlation between a structural damage studied by laser polarimetry and a functional lesion studied by Pulsar perimetry. There may be a temporal lapse between both defects which may explain our results.
Keywords: 484 nerve fiber layer • 432 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 624 visual fields