Frequency Doubling Technology Correlates With Selective Magno Stimulus Response On Calcarine Cortex Evaluated By Functional Magnetic Resonance Imaging

Abstract

Purpose: : To evaluate association between the magno and parvo stimulus response on functional magnetic resonance imaging (fMRI) and SAP and FDT visual fields in patients with glaucoma and controls.

Methods: : Patients and controls were submitted to a complete ophthalmic examination, including Humphrey Standard automated perimetry (SAP) 24-2 and Matrix frequency doubling technology (FDT) perimetry. To analyze fMRI data a manual segmentation was performed using FSL software, to obtain ROIs of calcarine cortex using the calcarine fissure to separate superior and inferior areas. The occipital pole area was obtained with a Harvard-Oxford Cortical Structural Atlas. Six areas were obtained: occipital pole and superior and inferior calcarine cortex for each hemisphere. For each area BOLD signal (%) was calculated in two different ways: using featquery (FSL) program and MATLAB routine. In featquery was obtained the BOLD signal and average of time series. In MATLAB routine, this time series of FSL were processed for each ROIs. The BOLD value obtained is the maxima value extracted for each period of stimulus. Ocular data (SAP, FDT) were compared to fMRI response to selective magno and parvo stimulus. Perimetry (SAP and FDT) results were divided into four quadrants (superior nasal, inferior nasal, superior temporal, inferior temporal). It was calculated the average of the total deviation for each quadrant, excluding the central point that corresponds to macula. To evaluate the association between the two psychophysics tests and fMRI response, generalized estimating equation (GEE) models were performed to account for the dependence between eyes and cortical segment of the same patient

Results: : Regarding magno stimulus, there was a statistically significant association with Bold 90% for SAP (p= 0,004) and FDT (p= 0,056), and with occipital for FDT. FMRI response to parvo stimulus was significantly associated with SAP results (p= 0,044) but not for FDT.

Conclusions: : A significant association between FMRI response to magno stimulus and FDT Matrix in glaucoma patients was observed.

Keywords: perimetry • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • visual cortex