  Recent Alzheimer's disease (AD) patient studies have focused on retinal
analysis, as the retina is the only part of the central nervous system which
can be imaged non-invasively by optical methods. However as this is a
relatively new approach, the occurrence and role of pathological features such
as retinal layer thinning, extracellular amyloid beta (A$\beta$) accumulation
and vascular changes is still debated. Animal models of AD are therefore often
used in attempts to understand the disease. In this work, both eyes of 24
APP/PS1 transgenic mice (age: 45-104 weeks) and 15 age-matched wildtype
littermates were imaged by a custom-built multi-contrast optical coherence
tomography (OCT) system. The system provided a combination of standard
reflectivity data, polarization-sensitive data and OCT angiograms. This
tri-fold contrast provided qualitative and quantitative information on retinal
layer thickness and structure, presence of hyper-reflective foci, phase
retardation abnormalities and retinal vasculature. While abnormal structural
properties and phase retardation signals were observed in the retinas, the
observations were very similar in transgenic and control mice. At the end of
the experiment, retinas and brains were harvested from a subset of the mice (14
transgenic, 7 age-matched control) in order to compare the in vivo results to
histological analysis, and to quantify the cortical A$\beta$ plaque load.
