Purpose:
To investigate the correlation between the structural and functional changes in glaucoma using Time-Domain (TD-OCT), Fourier-Domain Optical Coherence Tomography (FD-OCT) and Standard Automated Perimetry (SAP).
Methods:
Healthy and primary open-angle glaucoma individuals were enrolled in this observational, cross-sectional study. Peripapillary retinal nerve fiber layer (RNFL) thickness was assessed with the Stratus OCT Fast RNFL Scan, Cirrus OCT Optic Disc Cube 200x200 and Spectralis OCT RNFL protocols. Functional loss was assessed with the 24.2 Humphrey SAP. The visual field threshold data and the OCT RNFL data were divided into four sectors. A neural estimate model was used to evaluate the relationship between RNFL sectors and corresponding topographic SAP locations. Correlations were evaluated by Spearman’s rank correlation test.
Results:
One hundred and forty-five eyes of 79 individuals (19 normal, 20 early, 20 moderate and 20 advanced glaucoma) were enrolled in this study (mean age 61.65 years, range 38 to 85). Mean estimates (SD) of the retinal ganglion cells/μm2 for the SAP superior, temporal, inferior and nasal sectors were 25295 (144,526), 57,930 (34,816), 251,438 (98,250) and 213,410 (90,496) respectively. Overall mean estimates (SD) of the retinal ganglion cell axons/μm2for Stratus, Cirrus and Spectralis were 604,637 (312,293), 608,497 (284886) and 647,739 (317,186) respectively. Correlation between OCT and SAP ranged from 0.71 to 0.93 (Table)
Conclusions:
Neural estimates for the TD-OCT and SD-OCT showed good correlations with SAP, depending on the sector tested. Best correlations between structural andfunctional tests were found for the inferior and superior sections as well asfor the overall estimates.
Keywords: ganglion cells • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • nerve fiber layer