Traction on the retina induced by saccadic eye movements in the presence of posterior vitreous detachment

Abstract

Posterior vitreous detachment is a fairly common condition in elderly people. Tractions exerted by the detached vitreous on the retina may result in retinal tears and detachments. We studied how these tractions can arise from saccadic eye movements. Numerical simulations have been performed on a two-dimensional model of the vitreous chamber within a rigid spherical sclera, subjected to prescribed finite-amplitude rotations about a vertical axis. The vitreous chamber was assumed to be split into two regions: one occupied by the detached vitreous, modeled as an elastic viscous solid, and the other occupied by the separated liquefied vitreous, modeled as a Newtonian fluid. At the interface between the two phases, we also considered the presence of the vitreous cortex, modeled as an elastic membrane. We tested several different configurations of the interface. In all cases, we found that eye rotations generate large tractions on the retina close to the attachment points of the membrane. Comparing them, we identified configurations of the vitreous detachment that exhibit higher tractions. We also investigated how the response to saccadic movements depends on some physical parameters, in particular on the rheological properties of the solid phase and the membrane. The numerical simulations show that the generated tractions may be of the same order of magnitude as the adhesive force between the retina and the pigment epithelium. Therefore, the model provides a sound physical justification for the hypothesis that saccadic movements, in the presence of posterior vitreous detachment, could be responsible for high tractions on the retina, which may trigger retinal tear formation.

Preoperative Posturing of Patients with Macula-On Retinal Detachment Reduces Progression Toward the Fovea

“…22 Shear forces on the retina by eye and head movements are expected to affect RD progression as well. 23,24 Bed rest not only allows for specific positioning, but also helps to reduce eye and head movements. Although there is no evidence available, posturing at home may increase the risk of RD progression because of the traveling time, the lack of nurse surveillance, and the need to perform domestic duties.…”

Mechanical Models of the Dynamics of Vitreous Substitutes

“…Posterior vitreous detachment is primarily responsible for the generation of tractions on the retina that might produce retinal tears. These can possibly evolve into retinal detachment, since the detached vitreous often displays tight attachment points with the retina, where concentrated mechanical stimuli occur [1]. In the general population, nontraumatic phakic rhegmatogenous retinal detachment occurs in about 5.4 out of 100,000 persons and is among the most frequent causes of blindness in Western countries [2].…”

Intraocular currents, Bernoulli’s principle and non-drainage scleral buckling for rhegmatogenous retinal detachment

“…Dynamic traction is caused by eye (and some believe head) movements. 4 Saccadic and pursuit eye movements are usually rotational and can reach high angular velocities. 5 In the presence of a PVD, the content of the vitreous cavity no longer move bodily as a single semi-solid structure.…”

“…5 In the presence of a PVD, the content of the vitreous cavity no longer move bodily as a single semi-solid structure. 4 Being attached at the vitreous base, the anterior vitreous gel continues to move at roughly the same angular velocity as the eye wall. In contrast, being detached posteriorly, the posterior vitreous gel lags somewhat behind ( Figure 1).…”