Optical properties of ocular fundus tissues-an in vitro study using the double-integrating-sphere technique and inverse Monte Carlo simulation

Abstract

Various models have been published calculating the light transport at the ocular fundus either for interpretation of in vivo reflectance measurements or for the prediction of photocoagulation effects. All these models took the absorption spectra of the pigments located at the ocular fundus, melanin, haemoglobin, xanthophyll, and the photoreceptor pigments, into account. However, light scattering inside the single fundus layers has not been investigated in detail and was, therefore, neglected in the calculations or only considered by very rough approximations. This paper presents measurements on specimens of retina, retinal pigment epithelium, choroid, and sclera using the double-integrating-sphere technique. Absorption coefficients, scattering coefficients, and anisotropy of scattering were calculated by an inverse Monte Carlo simulation from the measured collimated and diffuse transmittance and diffuse reflectance. Conclusions are drawn for the interpretation of fundus reflectance measurements, which are a useful tool in diagnostics and photocoagulation dosimetry.

Integrating photoacoustic ophthalmoscopy with scanning laser ophthalmoscopy, optical coherence tomography, and fluorescein angiography for a multimodal retinal imaging platform

“…4(a)] specifically imaged five individual retinal vessels and the RPE due to strong optical absorption of hemoglobin and melanin. Unlike clearly resolved multiple retinal layers in the SD-OCT B-scan, other anatomic layers except for the vasculature and the RPE were invisible in the PAOM B-scan due to their low optical absorption coefficients 24 and poor axial resolution in the PAOM. 4 The 1 When we compare the PAOM and FA-SLO images, much finer details of the retinal capillaries can be observed in the FA-SLO image than in the PAOM image.…”

Human retinal circuitry and physiology.

“…This way, image degradation by the inhomogeneous optical properties of the retinal neuronal elements, which scatter light as it travels from the inner to the outer retina (Hammer, Roggan, Schweitzer, & Muller, 1995), is reduced.…”

Measuring Dynamics Of Scattering Centers In The Ocular Fundus

“…Ocular fundus tissues have been extensively studied by Hammer et al [7], who reported in their paper the optical properties summarized in Table I. shape and size of the molecules, interaction among other molecules, constraints due to membranes, and so forth.…”