Christine Curcio, PhD, shares histology update supporting review software and revised nomenclature for <3 μm OCT

Christine A. Curcio, PhD, delivered an update on histology and its critical role in advancing <3 μm optical coherence tomography (OCT) interpretation at the Heidelberg 2025 International SPECTRALIS Symposium – and Beyond (ISS), held June 13-14 in Heidelberg, Germany. "Histology is the study of tissue sections by microscopes that range in magnification and resolution themselves, and so the microscopy really has to be matched to the signal source in OCT,” said Curcio, emerita professor of ophthalmology and visual sciences at the University of Alabama at Birmingham Heersink School of Medicine.

With OCT now able to visualize reflectivity at subcellular levels, Curcio and her team are leveraging volume electron microscopy to correlate high-resolution tissue data with OCT B-scans. “We saw a complete RPE cell for the first time,” she noted—an achievement with major implications for understanding AMD and inherited retinal diseases.

A central theme of her talk was how new histologic techniques are informing refined software tools and a revised OCT nomenclature. “We built on the success of the 2014 international OCT consensus by Staurenghi et al,” Curcio explained, referencing a landmark framework that introduced terms like the ellipsoid zone and interdigitation zone. Among key additions in the updated system is the inclusion of the RPE basal lamina, which had been excluded from the original RPE-Bruch’s complex. This extracellular matrix thickens in AMD and forms basal laminar deposit (BLamD), which must be distinguished from neovascular structures. “BLamD, in turn, must be differentiated from type 1 macular neovascularization so that patients do not undergo anti-VEGF injections that will not be effective.”

Curcio also highlighted the need for anatomical precision in defining the foveal center, particularly in clinical trial design. “Attention to precision is really essential,” she concluded, underscoring how these advances will support both mechanistic insight and therapeutic development in outer retinal disease.