- 2026-04-20
- Investigative ophthalmology & visual science 67(4)
- Viet-Hoan Le
- Omar S El-Mulki
- Yi Zhang
- Hefu Pan
- Sivathanu Kumar
- Mengxi Shen
- Sara Beqiri
- Omar Badla
- Alessandro Berni
- James Kastner
- Giovanni Gregori
- Philip J Rosenfeld
- Ruikang K Wang
Study Design
- Type
- Observational
- Population
- age-related macular degeneration (AMD) cohort
- Methods
- Observational and experimental laboratory study analyzing volumetric OCT scans with hypoRCD from an AMD cohort; tissue phantom experiments with different oil droplets to model different refractive indices; proposed three metrics for quantification
Purpose
To investigate the optical mechanism and impact of the artifactual bending of Bruch's membrane (BM) beneath hyporeflective core drusen (hypoRCD) on optical coherence tomography (OCT).Methods
This observational and experimental laboratory study analyzed volumetric OCT scans with hypoRCD from an age-related macular degeneration (AMD) cohort. The optical mechanism underlying BM bending was examined using tissue phantoms with different oil droplets to model different refractive indices (RIs) of hyporeflective cores (hypoRCs). Three metrics were proposed to quantify hypoRCD: (1) hypocore bending index (CoreBI), (2) drusen bending index (DruBI), and (3) maximum bending index (Bmax). The impact of BM bending on choriocapillaris flow deficit (CCFD) analysis was assessed by comparing CCFD measurements before and after correcting BM segmentation under hypoRCD.Results
BM bending was consistently observed beneath the core region of hypoRCD in both structural OCT and optical attenuation coefficient (OAC) B-scans. Phantom experiments demonstrated that the bending was associated with differences in the RIs of the hypoRCs. The degree of bending, quantified by the CoreBI, increased with the RI of the core material (P < 0.001). The CCFD percentage beneath hypoRCD was significantly reduced by 25.9% ± 7.7% (P = 0.005) after correcting the BM segmentation. Morphological changes associated with the bending could be quantified using the three proposed metrics.Conclusions
BM bending induced by hypoRCD is an artifactual OCT feature that reflects the optical properties of the hypoRCs. This morphological characteristic may improve our understanding of hypoRCD, raise cautions in quantitation of CCFDs under hypoRCD, and provide additional insights into their role in AMD.