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A swept-source widefield deviation map can help identify eyes in the early stages of glaucoma, according to findings published in the British Journal of Ophthalmology.
Deviation maps, which compare the nerve layer thickness data and macular ganglion cell complex (GCC) thickness against an internal normative database, are widely used. However, this study recommends analyzing each peripapillary and macular area separately. This provides the ability to visualize the axon bundles from the ganglion cells at the macular area that converge around the optic disc.
Advancements in swept-source optical coherence tomography (SS-OCT) now enable examination of the thickness of a wider section of the neural layer compared with earlier devices. However, only a narrow portion around the optic disc center and macula have been used in the analysis.
To develop a widefield OCT deviation map from swept-source scans, 400 eyes, including 200 healthy eyes and 200 eyes with early glaucoma, were enrolled in a retrospective observational study. Patients received a comprehensive ocular examination, including widefield SS-OCT. The new map was compared with conventional deviation maps based on the area under the curve (AUC).
The widefield deviation map created using the normative widefield database showed the highest diagnostic ability for diagnosing early glaucoma (AUC=0.980 and 961 for color-coded pixels presenting <5% and <1%, respectively) among various deviation maps. Furthermore, its AUC was significantly superior to that of most conventional deviation maps (P <.05), according to researchers. In addition, the widefield deviation map demonstrated early structural glaucomatous damage across a comprehensive area. Researchers add that, since data of the GCC — including the RNFL layer — were used instead of those of the macular ganglion cell-inner plexiform layer, “the widefield deviation map of this study better depicted the continuity between the parts within and outside the peripapillary circle.”
The study’s authors note several limitations with their research, including that all enrolled patients were Korean, those with a high degree of myopia were excluded, and there was no control for anatomical variables. In addition, researchers report difficulties defining pixel size and did not analyze the location and shape of ocular damage.
Reference
Kim H, Park HM, Jeong HC, et al. Wide-field optical coherence tomography deviation map for early glaucoma detection. Br J Ophthalmol. Published Online July 22, 2021. doi:10.1136/bjophthalmol-2021-31950.
