Abstract
Purpose :
Optical coherence tomography (OCT) of the optic nerve (ON) is widely used to assess progression of glaucoma. Macular OCT is an alternative to follow glaucoma that is less influenced by imaging artifact. The association between the retinal nerve fiber layer thicknesses measured using each modality is poorly understood. The purpose of this study is to examine the concordance between focal thinning of ON OCT and regional sectoral thinning of the corresponding macular OCT.
Methods :
We retrospectively analyzed spectral-domain OCT (SD-OCT) data of 28 patients with primary open angle glaucoma (POAG) and 34 patients that were POAG suspects. These patients were seen at Drexel Eye Clinic from July 2015 to September 2018 and had OCTs obtained by the Heidelberg Engineering Spectralis device. Superotemporal (TS), inferotemporal (TI), and temporal areas on optic nerve (ON) were compared to inner sectors and outer sectors of the macula defined by the 1mm, 3mm, and 6mm ETDRS calculation circles. The data were graphed on scatterplots. SPSS Statistics software was used to calculate a correlation coefficient and P-value for each of the scatterplots. P-values less than 0.05 were considered statistically significant.
Results :
In both POAG and POAG suspects, TS thickness of ON was correlated with thickness of the 1-3mm superior region of the macula (r2=0.47, p<0.01) and 3-6mm superior region of the macula (r2=0.58, p<0.01), but not with the nasal regions of the OCT macula. TI thickness of ON was correlated with thickness of the 1-3mm inferior region of the macula (r2=0.65, p<0.01) and 3-6mm inferior region of the macula (r2=0.76, p<0.01), but not with the nasal regions of the OCT macula. The temporal thickness of ON had a weak correlation with the 3-6mm nasal region (r2=0.31, p=0.05) but not the 1-3mm nasal region (r2=0.16).
Conclusions :
Thickness of TS and TI regions of ON is related to the thickness of the superior and inferior macula respectively. The inferior disc, which the area with the most nerve fibers and that generally thins first in glaucoma, is best correlated to sectoral thinning on the OCT macula. Although the papillomacular bundle traverses the nasal macula before entering the temporal optic nerve, there is only a weak correlation between thicknesses of these two areas. These data serve as an important starting point to understand how focal thinning of peripapillary retinal nerve fiber layer is related to thinning in regional macular sectors.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.