Determining posterior vitreous structure by analysis of images obtained by AI-based 3D segmentation and ultrawidefield optical coherence tomography

Aims To determine the three-dimensional (3D) structure of the vitreous fluid including the posterior precortical vitreous pockets (PPVP), Cloquet's canal and cisterns in healthy subjects by AI-based segmentation of the vitreous of swept-source optical coherence tomography (OCT) images. In addition, to analyse the vitreous structures over a wide and deep area using ultrawidefield swept-source OCT (UWF-OCT). Methods Ten eyes of six patients with the mean age was 40.7 +/- 8.4 years and the mean refractive error (spherical equivalent) was -3.275 +/- 2.2 diopters were examined. Results In the UWF OCT images, the structure of the vitreous was observed in detail over 23 mm wide and 5 mm area. AI-guided analyses showed the complex 3D vitreous structures from any angle. Cisterns were observed to overlie the PPVP from the anterior. The morphology and locations of the cisterns varied among the subjects but tended to be similar in the two eyes of one individual. Cisterns joined the PPVPs superior to the macula to form a large trunk. This joined trunk was clearly seen in 3D images even in eyes whose trunk was not detected in the B scan OCT images. In some eyes, the vitreous had a complex appearance resembling an ant nest without large fluid-filled spaces. Conclusions A combination of UWF-OCT and 3D imaging is very helpful in visualising the complex structure of the vitreous. These technologies are powerful tools that can be used to clarify the normal evolution of the vitreous, pathological changes of vitreous and implications of vitreous changes in various vitreoretinal diseases.