​​Study Explores How to Boost Sensitivity of OCT in Glaucoma Progression

Future OCT software enhancements that increase RNFL segmentation beyond the typical 12 clock hours would increase the test’s diagnostic accuracy, these researchers argue. Their work aims to set the foundation for future development toward that goal. Photo: Andrew Rixon, OD. Click image to enlarge. In OCT scans of glaucomatous eyes, global thickness changes in the circumpapillary retinal nerve fiber layer (cpRNFL) offer clinicians an overview of disease activity over time. This metric, however, must be considered alongside the sectoral map, since thinning often presents itself in small, localized areas that may be obscured by a global metric. “This is similar to visual field progression, where global indices such as mean deviation provide a useful summary measure, but point-by-point analyses are ultimately more responsive to localized change,” wrote a multinational group of researchers in a recent paper for Translational Vision Science & Technology. The team explored methods for improving the accuracy of detecting localized RNFL changes without reducing specificity. Current OCT devices typically use a small number of sectors—four, six or 12—but these can’t achieve high sensitivity for detecting glaucomatous changes in cpRNFL thickness, explained the researchers in their paper. They developed a different prediction model called permutation analysis that might find its way into future OCT technology, the team believes. “The permutation of cpRNFL thickness profiles makes it possible to detect highly localized change in cpRNFL profiles from optical coherence tomography.”Using OCT data from 428 eyes of 255 glaucoma patients, the researchers performed statistical tests of progression in the cpRNFL at different numbers of sectors ranging from one (i.e., global thickness) to 360. The authors explained that this type of combined probability test addresses multiple comparisons and low specificity and “makes it possible to investigate change at finer spatial scales” without sacrificing specificity. At a 95% specificity, they reported a 28% positive rate for global thickness and a 35% rate for 12 sectors, increasing to 41% for 128 sectors. From this they concluded that at least 128 RNFL sectors were needed to achieve the highest sensitivity without decreased specificity, and noted in the study that the difference in positive rates between the global analysis and 128 sectors was likely to be clinically meaningful.“Like other analyses of change, including that of global cpRNFL thickness, the performance of the combined probability test can be affected by inter-visit differences in eye position, magnification, rotation and segmentation errors,” the authors concluded. “But, unlike with other analyses, these error sources will affect sensitivity only, and not specificity” (as long as these errors remain random rather than systematic, as discussed above). The researchers summed up their research by suggesting that it might help the task of estimating the statistical significance of change in cpRNFL thickness profiles. They cautioned, however, that, “such analyses must be evaluated not just in terms of specificity and sensitivity to change, but also for how effectively they support visualization and localization of change, and clinical interpretability and decision-making.”Click here for the journal source. Marín-Franch I, Artes PH, Abu SL, et al. Combined probability test for sectoral progression of the circumpapillary retinal nerve fiber layer thickness. Transl Vis Sci Technol 2025;14:9:4. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.