Light‐induced modifications of the outer retinal hyperreflective layers on spectral‐domain optical coherence tomography in humans: an experimental study

Abstract

Numerous small hyperreflective dots (HRDs) can be seen within the hyporeflective layer between the ellipsoid zone (EZ) and the interdigitation zone (IZ) on C-scan spectral-domain optical coherence tomography (SD-OCT) with a yet unknown variation under light conditions. The aim of this study was to explore light-induced SD-OCT changes in these HRDs. Methods: The study subjects were randomly assigned to two groups: Group 1 experienced a dark adaptation protocol followed by intense retinal photobleaching, while Group 2, serving as the control group, was exposed to constant ambient light without any variation. The number of HRDs was automatically counted. Results: Twenty healthy volunteers were prospectively included. The number of HRDs differed significantly over time (p = 0.0013). They decreased in Group 1 after dark adaptation and retinal photobleaching before returning to baseline levels 30 min later; conversely, they remained relatively constant in Group 2 throughout the study (p < 0.001). Light-skinned subjects had less HRD than dark-skinned subjects. Conclusion:We observed light-induced modifications in the space between the EZ and the IZ. We hypothesize that the HRDs visible in this zone correspond to melanosomes that are mobilized during the light stimulation protocol. Larger studies are recommended to further evaluate and confirm light-induced SD-OCT changes under physiological and pathological conditions.

Polarization-sensitive investigation of outer retinal OCT bands in the human eye

“…The RPE apical process present at the interdigitation zone contains melanosomes [20]. These melanosomes are known to participate in active photoprotection and can also generate backscattering signals [21]. The scattering signal from the interdigitation zone can explain the presence of the third band peak in cross-polarized signal at a shorter distance from the ELM layer compared to the third bank peak in parallel-polarized signal.…”

Polarization-Resolved Analysis of Outer Retinal Bands: Investigating Ballistic and Multiply Scattered Photons using FF-OCT

“…The RPE apical process present at the IZ band contains melanosomes [32]. These melanosomes are known to participate in active photoprotection and can also generate backscattering signals [33]. The multiply scattering signal from the IZ layer can explain the presence of the 3 rd band peak in the cross-polarization signal at a shorter distance from the ELM layer compared to the 3 rd bank peak in the parallel-polarization signal.…”

Optical coherence tomography in healthy human subjects in the setting of prolonged dark adaptation

“…diabetic retinopathy, macular diseases, etc. ); considerably fewer studies, however, have been performed on healthy human or mouse retinas, and those that have used bleaching or flash light stimuli 9 , 14 – 20 .…”