A mechanical model of retinal detachment

Abstract

We present a model of the mechanical and fluid forces associated with exudative retinal detachments where the retinal photoreceptor cells separate, typically from the underlying retinal pigment epithelium (RPE). By computing the total fluid volume flow arising from transretinal, vascular and RPE pump currents, we determine the conditions under which the subretinal fluid pressure exceeds the maximum yield stress holding the retina and RPE together, giving rise to an irreversible, extended retinal delamination. We also investigate localized, blister-like retinal detachments by balancing mechanical tension in the retina with both the retina-RPE adhesion energy and the hydraulic pressure jump across the retina. For detachments induced by traction forces, we find a critical radius beyond which the blister is unstable to growth. Growth of a detached blister can also be driven by inflamed lesions in which the tissue has a higher choroidal hydraulic conductivity, has insufficient RPE pump activity, or has defective adhesion bonds. We determine the parameter regimes in which the blister either becomes unstable to growth, remains stable and finite-sized, or shrinks, allowing possible healing. The corresponding stable blister radius and shape are calculated. Our analysis provides a quantitative description of the physical mechanisms involved in exudative retinal detachments and can help guide the development of retinal reattachment protocols or preventative procedures.

Vascular Endothelial Growth Factor Modulates the Function of the Retinal Pigment Epithelium In Vivo

“…Although the values were strain specific, they were in agreement with data published for the hydraulic conductivity (0.756 lLÁcm À2 Áh À1 Ámm Hg À1 ) 35 and active pumping (~10 À8 mÁs À1 »3.6 lLÁcm À2 Áh À1 ) of ex vivo RPE tissue for other species. 31,35 Our experiments represent the first direct measurement of RPE hydraulic conductivity in vivo. 30 Vascular endothelial growth factor is widely accepted as a vascular permeability factor in endothelial cells 6,36 including retinal vasculature, 37 and human recombinant VEGF has been shown to be active on the blood vessels in rabbit eyes.…”

Mechanical spectroscopy of retina explants at the protein level employing nanostructured scaffolds

“…The forces associated with retinal detachment depend on many factors such as pressure-driven flows, active retinal pigment epithelium (RPE) pump-mediated drag, cell-cell adhesion forces, and retinal tension forces. 39 The origin of the tension inside the retina is still unknown. The retinal structure and function are understood properly but its mechanical properties have not received great attention until now and are still a matter of debate.…”

TraumaticStaphylococcus gallinarumendophthalmitis and detachment of a pallid retina

“…The same force applied to the normal appearing superior retina did not detach it, even though the vitreous separation was extended way up to the vitreous base. A healthy retina does not detach with the shearing forces of vitreous separation unless the retinal pigment epithelium (RPE) pumps fail or retina-RPE adhesion energy reduce 9. The force required to separate the retina from RPE in experimental conditions is ∼0.01–0.1 J/m 2 9.…”

“…A healthy retina does not detach with the shearing forces of vitreous separation unless the retinal pigment epithelium (RPE) pumps fail or retina-RPE adhesion energy reduce 9. The force required to separate the retina from RPE in experimental conditions is ∼0.01–0.1 J/m 2 9. Presuming a non-rhegmatogenous aetiology for the detachment, we preferred to observe rather than use a long-term tamponading agent.…”