Quantitative in-vivo characterization of optical properties of ocular tissue for diagnosis and monitoring of chorioretinal diseases

Current clinical ophthalmic practice focuses on assessing the (chorio)retinal condition based on many imaging techniques, including indirect ophthalmoscopy, slit-lamp examination, SLO, (auto)fluorescence and OCT. These techniques are capable of depicting the general appearance and anatomical structure of the chorioretinal complex, but do not quantitatively represent the state of the retina. In this proposal, we will develop techniques to quantitatively assess various optical properties of the retina and its separate layers, thereby providing information about the health status of the retina. These properties are the attenuation coefficient, polarization properties and the spectral signature of the retina. The attenuation coefficient is related to the scattering properties of the tissue and we have shown that the attenuation coefficient of the RNFL correlates with glaucomatous damage to this layer. Polarization is an important property of some of the retinal layers, such as the RNFL and the retinal pigment epithelium (RPE), that are for example involved in glaucoma and AMD, respectively. The spectral signature of the retina contains information about its biochemical constitution and oxygenation and can reveal information about metabolic activity or retinal ischemia. We aim to develop quantitative methods to study the retinal layers and correlate these quantitative measures to diagnostic criteria to provide new means for improving clinical care in ophthalmology. The project includes building prototype implementations and performing several pilot studies to assess the usefulness of each technique and optical property for various diseases of the retina. The objectives of this proposal can be summarized as follows: - To accurately derive and validate the attenuation coefficient from various structures within the chorioretinal OCT data by novel mathematical modeling. - To develop novel instrumentation to measure and derive polarization-related properties by PS- OCT. - To measure and analyze the spatially-resolved spectral signature of the retina by a multispectral MP-SLO system and to correlate the spectral signatures with the three dimensional structure as determined by OCT. - To evaluate the value of these optical properties in diagnosis and monitoring of glaucoma, AMD, central serous retinopathy (CSR), macular edema due to retinal vein occlusions (RVO) and DRP, and various other diseases of the (chorio)retinal complex. Reaching these objectives will reveal new methods of improving diagnosis (accuracy, sensitivity, reproducibility) and monitoring (progression and treatment) of diseases of the retina, ultimately leading to reduced blindness and loss of vision in an aging population.