Development of a Multi-Disciplinary Tool to Investigate Vision Loss due to Posterior Vitreous Detachment

The objective of this proposal is to develop a unique mechanics-based imaging methodology that allows multidisciplinary investigation of vitreous liquefaction and microscale vitreoretinal adhesion to elucidate mechanisms of vision loss from posterior vitreous detachment. Posterior vitreous detachment (PVD) occurs in 24% of all individuals by the age of 50-59 years and 87% of all individuals by the age of 80-89 years. In and of itself, complete detachment of the vitreous from the retina is a naturally occurring preventative mechanism for vision loss. Specifically, as the eye ages, the gel-like vitreous begins to liquefy (liquefaction). Concurrently, adhesion between the vitreous and retina weakens. The two well-timed age-related changes have chemical and mechanical components that work synergistically to cause the vitreous to cleanly and harmlessly separate from the retina. However, if liquefaction occurs early or adhesion is not sufficiently weakened, retinal tearing and/or detachment will occur, leading to vision loss. To date, the mechanisms of liquefaction and vitreoretinal adhesion are unknown. Therefore, there is no knowledge of why liquefaction occurs early or vitreoretinal adhesion weakening is delayed. Identification of the mechanisms involved in PVD will allow both processes to be manipulated such that they work in a cooperative rather than destructive manner, and to decrease the risk of vision loss. In this proposal, we will develop a testing apparatus to evaluate the microscale mechanical mechanisms of liquefaction and vitreoretinal adhesion. Specifically, we will use surface-modified magnetic microbeads to mechanically manipulate collagen fibers in the vitreous. During the manipulation, we will measure time-dependent changes in liquefaction, microadhesion forces at the vitreoretinal interface, and identify failure mechanisms between the vitreous and retina. Confocal reflectance and second harmonic generation will be used to image the manipulation of the collagen fibers in real-time.

Current Status

2021-09-14
Abstract:
The objective of this proposal was to develop a mechanics-based imaging tool for multidisciplinary investigation of vitreous liquefaction and vitreoretinal adhesion to elucidate mechanisms of vision loss from posterior vitreous detachment (PVD). PVD occurs in 87% of people <85 years of age. In and of itself, complete detachment of the vitreous from the retina is a preventative mechanism for vision loss. As the eye ages, the gel-like vitreous begins to liquefy (liquefaction). Concurrently, adhesion between the vitreous and retina weakens. The two well-timed age-related changes work synergistically to harmlessly separate vitreous from the retina. However, if liquefaction occurs early or adhesion weakens late, retinal tearing and vision loss may occur. The mechanisms of liquefaction and vitreoretinal adhesion are unknown. Identification of these mechanisms will allow manipulation of the processes to work in a cooperative rather than destructive manner. In this proposal, surface-modified magnetic microbeads were used to manipulate vitreal collagen fibers and measure time-dependent changes in vitreous under confocal reflectance. The experimental design, devices, and data from this project lay the groundwork necessary to pursue federally funded projects to investigate mechanisms of PVD, and develop strategies to minimize vision loss with age and disease.