Abstract
Purpose:
To investigate which OCT optic nerve head parameters are most associated with field loss in patients with asymmetric glaucoma.
Methods:
A retrospective chart review was conducted of 64 patients who underwent a Humphrey visual field and Cirrus OCT for POAG from 2010-2014. Degree of glaucoma asymmetry was calculated as the difference in mean deviation (MD) and difference in pattern standard deviation (PSD) between eyes for each subject. Asymmetry of OCT optic nerve head parameters were calculated for retinal nerve fiber layer thickness (RNFL), average cup to disc ratio, and vertical cup to disc ratio by taking the difference between each eye. For rim area, disc area, and cup volume asymmetry was calculated using the percent difference between each eye. Pearson's correlation was used to measure the relationship between each calculated OCT variable and the degree of glaucoma asymmetry derived from MD and PSD.
Results:
Percent difference in rim area correlates strongly to difference in MD (r=0.701, P<0.01), and weakly to difference in PSD (r= -0.249, P=0.47). Difference in RNFL thickness has a moderate correlation to MD difference (r=0.394, P<0.001) and PSD difference (r=-0.35, P<0.001). Vertical C:D ratio has a moderate correlation to difference in MD (r=-0.473, P<0.001) and difference in PSD (r=0.312, P=0.12). Difference in average C:D ratio, percent difference of disc area, and percent difference of cup volume were not found to correlate to difference in MD or difference in PSD.
Conclusions:
In our study, we find that OCT rim area has the highest correlation with degree of glaucoma asymmetry.