  One of the greatest needs in modern ophthalmology is access to the eye
choroid in vivo. Without it, it is difficult to introduce new therapies and to
understand most of the pathological changes in the eye, because of the total
blood flow in the eye is caused by the choroidal circulation. It is entirely
responsible for the metabolism of photoreceptors, which each of us feels every
day and senses when its deficits begin. Optical selection of choroid and
choriocapillaris by currently used imaging techniques such as indocyanine
angiography, scanning laser ophthalmoscopy or optical coherence tomography
(OCT) is limited by insufficient lateral resolution, depth of penetration and
the presence of strong light scattering effects. Here we report a
Spatio-Temporal Optical Coherence Tomography (STOC-T) that maintains
microscopic quality of in vivo reconstructions of anatomical layers when
imaging chorioretinal cross-sections in a coronal anatomic plane. STOC-T
performs high definition volumetric imaging in all projections, enabling
reconstruction of anatomical details of the retinal and choroidal layers with
unprecedented quality by using an extra phase randomization for low spatial
coherence. We also demonstrate that STOC-T can detect blood flow and reveal
vascular networks in various chorioretinal layers that are otherwise invisible
to OCT. This capability highlights the unique value of STOC-T angiography.
These technical advances enable acquisition of detailed choroidal structures,
such as Satller layer and choriocapillaris, that are usually buried behind
speckle noise and blurred by eye motion artifacts in conventional OCT. By
imaging the retina and choroid with high contrast, we were able to perform
detailed morphometric analysis, which is the basis for the anticipated clinical
utility of the method in monitoring disease progression and therapeutic
responses of the eye.
