Macular Posterior Vitreous Detachment: Mechanical Insights From Volume-Rendered Swept Source Optical Coherence Tomography

Summary

Macular PVD commonly involves circumferential cortical tearing (rather than detachment) due to shallow angle of tractional forces. May contribute to subsequent ERM formation —Retrospective, volume-rendered SS-OCT, 53 eyes

Abstract

Purpose: To characterize the structural features and mechanical failure patterns of macular posterior vitreous detachment using volume-rendered swept source optical coherence tomography and to analyze the forces governing cortical tearing versus vitreomacular separation.

Methods: In this retrospective study, eyes with developing or recent macular posterior vitreous detachment were imaged with swept source optical coherence tomography optimized for vitreous visualization by defocusing into the vitreous cavity. Volumetric data sets were processed and rendered three-dimensionally. Structural findings were analyzed descriptively and interpreted using vector-based mechanical modeling of cortical tensile forces and insertion geometry.

Results: Fifty-three eyes of 44 patients were imaged; 48 were evaluable. Circumferential tears of the posterior vitreous cortex were identified in 43 of 48 eyes (89.6%), including partial and complete tears. In a minority of eyes, detachment occurred without cortical rupture. The premacular bursa was preserved in partial tears and absent in complete tears. Measured insertion angles at the vitreomacular interface were shallow (<10°). Vector analysis demonstrated that at small insertion angles, the normal component of cortical tension is markedly attenuated (F⊥ = F sin θ), favoring cortical rupture at the insertion site over adhesive failure at the macula. Volume rendering demonstrated residual full-thickness cortical plaques adherent to the macular surface after tearing.

Conclusion: Volume-rendered swept source optical coherence tomography demonstrates that macular posterior vitreous detachment commonly involves circumferential cortical tearing. Mechanical analysis indicates that shallow insertion geometry favors cortical rupture as an initial failure mode, dissipating traction but leaving a residual cortical plaque that may contribute to subsequent epiretinal membrane formation.