Wavelength-dependent optical properties of melanosomes in retinal pigmented epithelium and their changes with melanin bleaching: A numerical study

In this paper, we present the first numerical study on full metrics of wavelength-dependent optical properties of melanosomes in retinal pigmented epithelial (RPE) cells. T-matrix method was used to simulate the spheroidal shapes of mature melanosomes, and the complex refractive index was calculated by a subtractive Kramers-Kronig relation for melanin. The validity of the method was first confirmed by Mie theory, and corroborated by a comparison between visible light and near infrared (NIR) optical coherence tomography (OCT) on human retinal imaging. We also studied the changes of melanosome optical properties due to melanin bleaching by numerically reducing the absorption of melanin. This study implies a unique approach to detect melanin changes specifically in RPE by a spectroscopic contrast of optical coherence tomography.