Swept Source OCT en-face imaging of vitreous cavity reveals topographic relationship of premacular bursa, Cloquet’s canal, prevascular vitreous fissures and cisterns

Abstract

Purpose : To examine the posterior vitreous of healthy subjects using SS-OCT and characterize the topographic relations of the various liquid spaces.

Methods : Zeiss PLEX Elite SS-OCT was used to acquire both 12mm vertical and horizontal high resolution scans, as well as 12x12mm (1024x1024) cube. 20 right eyes of healthy subjects aged 20 – 35 years old and an axial range of 23.0-26.6 were examined. Vitreous scans were segmented parallel to the vitreoretinal interface. Near-infrared, cross-sectional, and en-face images were correlated (see Figures 1 and 2).

Results : Correlation of en-face and cross-sectional B-scans confirmed that the premacular bursa and Cloquet’s canal connect at a variable distance from the optic nerve superiorly and follow a common course towards anterior and superior that escapes the area of detection. The bursa-canal fusional complex followed a relatively straight course through the vitreous in younger patients, whereas the course was more undulating and deflected superiorly in older patients. Hyporeflective spaces observed on B-scans could be topographically correlated to 1^st and 2^nd order retinal vessels, both arterioles and venules.

Conclusions : SS-OCT scans of unprecedented resolution and depth revealed the topographic relationships of the various vitreous spaces and confirmed a broad superior connection and superior extension of premacular bursa and Cloquet’s canal. This challenges concepts supported by earlier generation SS-OCT en-face studies. The prevascular location of hyporeflective spaces could be confirmed on overlays of vitreous scans normalized to the vitreoretinal interface and the corresponding near infrared images of the retinal vasculature.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Figure 1: A) An en face view of the retinal circulation in the right of a study patient. B) En face sections of the vitreous, segmented parallel to the vitreo-retinal interface demonstrates a clear view of the premacular bursa, Cloquet’s canal and prevascular vitreous fissures and cisterns that correlate with the retinal vasculature.

 

Figure 2. A) A horizontal cross-sectional scan at the fovea with increased contrast allows for clear visualization of the premacular bursa. B) This bursa may be manually segmented and the cross-sectional area calculated for comparison across subjects.