Measurement of retinal vascular permeability in a rat model using spectroscopic optical coherence tomography

Abstract

Optical coherence tomography (OCT), a diagnostic tool which can perform non-contact, noninvasive, cross-sectional imaging of the retina and anterior eye in real time, has dramatically improved in its resolution and speed in the recent years. In addition to the advancement in hardware, different OCT methods for functional measurements, such as Doppler OCT for quantifying blood flow and generating angiography using OCT phase information, polarization sensitive OCT for measuring intrinsic mechanical / optical tissue property using light of different polarizations, and spectroscopic OCT for measuring blood oxygenation using multiple wavelengths, have been demonstrated and developed. In this thesis, a dual-wavelength spectroscopic OCT technique is investigated to detect and quantify retinal vascular permeability changes in a small animal model. By injecting an intravascular dye that can act as a wavelength-dependent absorbing contrast agent into the bloodstream of a small animal, retinal vascular permeability changes induced by retinal diseases or external agents directly injected into the vitreous could be measured using spectroscopic OCT. Because OCT enables depth-resolved imaging of the retina, this technique may enable quantitative mapping of vascular permeability in vivo, which may have a significant impact on understanding the mechanisms of diseases that alter retinal vascular permeability, such as diabetic retinopathy. In this study, an OCT system with a diffraction-limited small animal imaging interface and a dual-wavelength OCT spectrometer for spectroscopic measurements was designed and built. Using this dual-wavelength spectroscopic OCT system, the rat retina could be imaged at two different wavelength bands simultaneously, and methods for analyzing spectroscopic OCT data were investigated for retinal vascular permeability measurement.