Quantitative multimodal retinal imaging

点击翻译按钮获取中文摘要

Project Summary-Abstract Our ultimate goal is to develop a multimodal VIS-OCT platform for retinal imaging to improve patient care and to advance clinical research. We proposed to develop a visible-light optical coherence tomography (VIS-OCT) platform for multimodal multifunctional imaging of the retina. Two novel VIS-OCT based imaging technologies will be built in this platform: quantitative fundus autofluorescence (FAF) or VIS-OCT-FAF, and retinal nerve fiber layer (RNFL) spectral contrast OCT or DUAL-OCT-RNFL. The two new technologies will add new tools for ophthalmologists to make early diagnosis and better monitor retinal diseases. The proposed work is based on hypotheses that are strongly supported by our theoretical modeling and solid preliminary data. We hypothesize that 1) Quantification of absolute FAF intensity can be achieved by normalizing raw FAF signals with an internal reference and an external standard fluorescence reference; 2) RPE OCT signals simultaneously acquired with FAF can serve as an internal reference; and 3) The spectral contrast of the RNFL can be used as a biomarker for RNFL damage by elevated IOP. Three Specific Aims are proposed. Aim 1: To develop a VIS-OCT platform for VIS-OCT-FAF and DUAL-OCT-RNFL imaging. We will develop and refine the VIS-OCT platform consisting of a VIS-OCT centered at 480 nm, a NIR-OCT centered at 840 nm, and a FAF detection module. A reference target with known fluorescence efficiency and reflectance placed in the intermediate retinal imaging plane will serve as a reference to normalize raw data to obtain absolute FAF intensity and quantitative RNFL spectral reflectance. The reference target will use a PMMA slide stained with A2E as fluorescent molecule. We will introduce the A2E equivalent unit (AEU) as a measure of FAF. Aim 2: To study VIS-OCT-FAF and DUAL-OCT-RNFL imaging in phantom and animals. We will test the system in phantom and animals to verify the capabilities of the VIS-OCT platform, to calibrate and obtain feedback for fine-tuning the hardware and algorithms. Phantom studies will use a model eye with A2E, melanosome and TiO2 to simulate lipofuscin, absorption and scattering in RPE. FAF images from albino and pigmented rats of different ages will be studied. A2E in each imaged eye will be quantified by mass-spectroscopy to verify the accuracy of FAF signals. Elevated IOP will be induced on rats by photocoagulation to the trabecular meshwork. RNFL spectral contrast images from eyes with or without increased IOP will be compared. Aim 3: To study VIS-OCT-FAF and DUAL-OCT-RNFL imaging in human subjects. Our ultimate goal is to develop a multimodal VIS-OCT platform for retinal imaging to improve patient care and to advance clinical research. Studies in this Aim will allow us to learn how the systems behave in a real clinical setting. We will image normal subjects of 6 age groups to establish age-based normative data. Patients with early dry AMD and Stargardt’s disease will also be studied. In the RNFL imaging studies, we will image 6 age groups of normal individuals to establish age-based normative data. Patients with early stage glaucoma will be studied.