Abstract
Purpose :
The management of rhegmatogenous retinal detachment (RRD) involves the use of intraocular tamponades. The most common types of vitreous substitutes include intraocular gas and silicone oil (SO). Retinal displacement, also described as a low integrity retinal attachment (LIRA), is a common complication that occurs after RRD repair, particularly following pars plana vitrectomy (PPV). Here, we developed a theoretical computer model to investigate the physical factors that contribute to retinal displacement.
Methods :
We developed a computer simulation model on MATLAB to calculate the contact angle and pressure between the endotamponade and the retina using interfacial tension and the densities of gas, SO, and the vitreous. A second simulation was used to determine the dynamics of fluid motion in the subretinal space and to calculate any deformations of the retina.
Results :
We demonstrated that the larger the volume of a gas tamponade, the greater the contact pressure on the retina over a greater area of contact. A gas tamponade that filled 93% of the ocular cavity, as in PPV, exerted a pressure that was four times higher than a tamponade that filled 14% of the ocular cavity, as in pneumatic retinopexy. Moreover, for the same fill ratio, gas had a larger contact angle and contact pressure than SO. At 93% fill, gas exerted a contact pressure of 1.5 mmHg on the retina at a contact angle of 125o, while SO exerted 0.024 mmHg at a contact angle of 100o.
Furthermore, endotamponades stretch the retina by displacing subretinal fluid to non-contact areas, causing retinal displacement. A gas tamponade that filled 14% of the ocular cavity stretched the retina an order of magnitude lower than one that filled 93%, suggesting a greater risk of retinal displacement in PPV. In addition, at the same fill volume, a SO tamponade stretched the retina significantly less than a gas tamponade, indicating that a SO tamponade may confer less risk of retinal displacement.
Conclusions :
Our findings suggest that endotamponades stretched the retina by displacing the remaining subretinal fluid after RRD repair. This retinal stretch may be an important mechanism underlying retinal displacement. The degree of gas filling and the type of endotamponade may be modulated to reduce the risk of retinal displacement.
This is a 2021 ARVO Annual Meeting abstract.