APR 16, 2021
This retrospective cohort study measured structural and functional changes among glaucoma and glaucoma suspects.
Researchers used spectral-domain OCT and standard automated perimetry (SAP) to assess 6,138 eyes of 3,669 patients enrolled in the Duke Glaucoma Registry. Study patients had 6 or more months of follow-up and 2 or more reliable tests from each modality. The rates of change were calculated and categorized using pre-existing cut-offs.
Overall, 27,182 OCT visits and 19,812 SAP tests were analyzed. The average rate of change for global retinal nerve fiber layer (RNFL) thickness on OCT was -0.73 μm/year while the average decline for SAP was -0.09 dB/year. In eyes with primary open-angle glaucoma (POAG), 28.3% showed at least moderate rate of change on OCT compared with 13.5% on SAP. The odds of detecting moderate or fast rate of change was 2.5-times greater with OCT than SAP. OCT also detected more fast progressors compared with SAP. There was significant disagreement between OCT and SAP for the classification of rates of progression as slow, moderate and fast.
This study has all the limitations of a retrospective study. In addition, vision and cataract status were not factored in but could have impacted measurements on both testing modalities and would have contributed to a faster rate of change that was attributed to glaucoma progression.
These findings suggest the rates of change in SAP and OCT often disagree, indicating it is still clinically necessary to monitor both structural and functional tests.