Visible light OCT improves imaging through a highly scattering retinal pigment epithelial wall

Area of Science:

• Biomedical Optics
• Ophthalmology
• Medical Imaging

Background:

• Conventional wisdom in biomedical optics suggests longer wavelengths facilitate deeper tissue imaging.
• Bruch's membrane (BM) visualization is critical for understanding retinal health.
• Pigmented eyes present imaging challenges due to the retinal pigment epithelium (RPE) layer.

Purpose of the Study:

• To investigate the effect of visible light wavelengths on optical coherence tomography (OCT) of Bruch's membrane (BM).
• To challenge the assumption that longer wavelengths are superior for deep tissue imaging in biomedical optics.
• To determine optimal wavelengths for visualizing BM in non-pathologic human and mouse eyes.

Main Methods:

• Visible light optical coherence tomography (OCT) was employed.
• Imaging was performed on non-pathologic human and mouse eyes.
• Monte Carlo simulations of radiative transport were used to model light interaction with tissue.

Main Results:

• Shorter visible wavelengths unexpectedly improved BM visualization in pigmented eyes.
• The RPE layer, containing melanosomes, significantly impacts imaging.
• Monte Carlo simulations indicated preferential attenuation of multiply scattered light from the RPE at shorter wavelengths.

Conclusions:

• Shorter visible wavelengths can be advantageous for imaging structures like BM behind scattering layers.
• This finding provides a counter-example to established principles in biomedical optics.
• Optimizing wavelength selection is crucial for effective deep tissue imaging in specific biological contexts.