The premacular bursa's shape revealed in vivo by swept-source optical coherence tomography
OBJECTIVE: To resolve the controversy surrounding the shape and relationship of posterior vitreous spaces by characterizing the connections between the premacular bursa, the area of Martegiani, and Cloquet's canal. DESIGN: Comprehensive posterior vitreous maps were created using swept-source optical coherence tomography (SS OCT) in a cross-sectional study. PARTICIPANTS: The posterior vitreous of 102 eyes of 51 volunteers 21 to 54 years of age without ocular pathologic features was imaged using SS OCT. METHODS: The DRI OCT-1 Atlantis 3D SS OCT (Topcon Medical Systems, Oakland, NJ) was used to acquire scans of the posterior vitreous over an 18x18-mm area. MAIN OUTCOME MEASURES: Posterior vitreous spaces and their relationships were identified. RESULTS: The premacular bursa was identified in all 102 eyes and was found to extend superiorly beyond our scanning ability at a variable angle. No discernible superior borders could be identified. Instead, a connection of the bursa with the preoptic area of Martegiani or its extension, Cloquet's canal, was found in 101 of 102 eyes. This connection occurred at a variable distance from the optic nerve, where it formed a flat and broad superior channel. The skyward direction of this channel was found to be gravity dependent in all 14 eyes of the 7 subjects examined in various head positions. Although SS OCT was able to identify vitreous degeneration, the above changes were present in 28 eyes even without any discernible vitreous degeneration. CONCLUSIONS: The premacular bursa, also called the posterior precortical vitreous pocket, was found to continue superiorly beyond the posterior pole without a detectable border. The bursa fused broadly with the extension of the preoptic area of Martegiani, namely Cloquet's canal, or the hyaloidal tract of Eisner. These findings suggest that there is a direct anteroposterior connection between the retrolental and premacular and preoptic spaces already existent in the eyes of young adults before the occurrence of vitreous degeneration. This observation may have important implications with respect to the movement of intrinsic and extrinsic mediators between the anterior and posterior segments.
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