Abstract
Purpose:
To measure the thickness of inner retinal layers in the macula using frequency domain-optical coherence tomography (fd-OCT) in patients with permanent temporal hemianopia from chiasmal compression and to compare these measures to visual field (VF) loss.
Methods:
33 patients with permanent temporal VF defects and 36 age- and sex-matched healthy subjects underwent 24-2 VF testing with standard automated perimetry (Carl Zeiss Meditec) and macular thickness measurements with fd-OCT cube scans (Topcon Inc). One eye of each subject was studied. The fd-OCT scans were segmented with an automated algorithm, and then manually hand-corrected.[1,2] For each scan, we determined, the thickness of the retinal nerve fiber layer (RNFL), the combined retinal ganglion cell plus inner plexiform layers (RGCL+), and the inner nuclear layer (INL), as well as total retinal thickness. Measurements were averaged for each quadrant of the macular region. VF loss was estimated using the central 16 test points in the VF, a region roughly corresponding to the OCT scan. Comparisons between groups was made using the Student’s t test. Correlations between measurements were also verified using either Pearson’s (VF loss in 1/Lambert units) or Spearman’s (VF loss in dB units) correlation.
Results:
In all quadrants, RNFL, RGCL+ and total retinal thickness measurements were significantly smaller in patients with chiasmal compression than in healthy controls. The largest differences were found in the RNFL thickness in the superior nasal quadrant (average loss of 23 μ, p<0.001) and the RGCL+ thickness of the inferior nasal quadrant (average loss of 20.5 μ, p<0.001). INL thickness was not significantly different compared to controls. A significant correlation was found between RNFL, RGCL+, and total macular thickness and the corresponding VF mean sensitivity. The strongest association was observed between superonasal quadrant RGCL+ thickness and the inferotemporal mean VF loss in 1/Lambert (r=0.805, p<0.001) and in dB (r=0.765, p<0.001).
Conclusions:
Although fd-OCT RNFL and macular thickness measurements were correlated with VF loss, the strongest correlation was found with quadrantic macular quadrant RGCL+ thickness. RGCL+ thickness measures may be useful for quantifying neuronal loss in patients with chiasmal compression. 1. Raza et al. AO 2011; 2. Yang et al. Opt Express 2010
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
629 optic nerve •
758 visual fields