Purchase this article with an account.
Garth G. Whelan, Abbas Shirinifard, James A. Glazier; RPE Tears: An in silico Perspective. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5837.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
We use computational modeling to evaluate the possibility of several theoretical etiologies for retinal pigment epithelium (RPE) tears in response to treatment of occult choroidal neovascularization (CNV). We test both hydrostatic pressure beneath the RPE and a decrease in the volume of the tissue or fluid between the RPE and Bruch’s membrane (BrM) as they have been mentioned in the literature as theoretical causes for RPE tears.
We use computer simulations, implemented in Compucell3D, to model the RPE in occult CNV and a wide range of biomechanical forces similar to several suggested etiologies. We study mechanical stress in the RPE due to hydrostatic pressure between the RPE and Bruch’s membrane, or a decrease in volume of the sub-RPE fluid or the fibrovascular tissue, with various combinations of forces representing tension originating from different sources within the eye. In the model we represent RPE, BrM and medium, including cell-cell adhesion and force from the cytoskeleton binding cells together. Depending on the etiology we test, we add an external force representing pressure, and other forces representing other biomechanical forces such as shear stress.
We find a decrease in volume of the sub-RPE fluid could not cause a tear in our computational model in most cases. As decrease in volume of about 12.5% is usually seen after weeks of treatment, this is not a reasonable tear cause in our model. However, as a decrease in volume of fibrovascular tissue may be anisotropic, this leads to a possibility of tear formation. Increased hydrostatic pressure was enough to create a tear. The addition of a tangential force to the RPE would create tears in situations with hydrostatic pressure which would not tear otherwise.
As in our computational model a decrease in volume of the sub-RPE fluid is not able to cause a tear in most cases, such a decrease in volume is a less likely etiology. Both hydrostatic pressure with and without tension can cause tears, leading to our belief that among the hypotheses tested, any hypothesis with hydrostatic pressure could lead to a tear. A tangential force causing tension could create RPE tears when otherwise tears would not occur, making tension a possible player in tear formation. There is also a possibility that a decrease in volume of the fibrovascular material beneath the RPE could cause a tear.
This PDF is available to Subscribers Only