Abstract
Purpose :
Compression of the optic chiasm leads to visual field loss and retrograde degeneration of the retino-geniculate pathway, which can be measured by optical coherence tomography (OCT). Macular ganglion cell complex has been particularly useful clinically and often correspond to the pattern and severity of visual field (VF) loss. In this study, we compared OCT and OCT angiography (OCTA) in patients with chiasmal lesions and determine whether they correlate with each other and VF loss.
Methods :
We performed a retrospective study of 27 subjects, 10 (20 eyes) with chiasmal compression and 17 controls (24 eyes). Only subjects with high quality static perimetry (Humphrey visual field 24-2), OCT, and OCTA studies were included. In patient group, we included those with mean deviation (MD) worse than -2dB. We analyzed whole eye as well as nasal/temporal hemifield and 4 quadrants of mean deviations and compared VF with corresponding OCT macular ganglion cell complex (GCC) thickness and macular OCTA superficial capillary plexus measurements including vessel area density (VAD), vessel skeletal density (VSD), vessel complexity index (VCI), vessel perimetry index (VPI), vessel diameter (VD) and flux. OCTA analyses were performed with MATLAB scripts and statistical analyses using Prism (GraphPad).
Results :
Analysis of macular OCTA revealed there was significant decrease in global perifoveal VAD, VCI, VSD, VPI in chiasmal compression patients compared to controls (p < 0.0001) and no changes in VD and flux. In contrast to macular ganglion cell complex, which exhibited significant regional thinning corresponding to pattern of visual field loss, there was no such regional loss of vessel area density in corresponding hemi retina or quadrants. Because there was no regional loss of vascular density, there was no correlation between VAD and GCC or between VAD and corresponding visual field mean deviation when divided into hemi- or quadrants of macula.
Conclusions :
Retrograde degeneration due to chiasmal compressed led to global rather than regional loss of peri-foveal vessel density on OCTA, in contrast to macular ganglion cell complex, which exhibited significant thinning corresponding to pattern and severity of visual field loss. The lack of regional specificity suggests that local vessel density does not reflect local loss of retinal ganglion cells and decrease metabolic demand.
This is a 2020 ARVO Annual Meeting abstract.