Abstract
Purpose :
MIGS devices that create an artificial fistula between the anterior chamber(AC) and subconjunctival space(SCS) can effectively reduce intraocular pressure (IOP). Despite this, chemotherapeutic agents are required to prevent fibrosis and subsequent device failure. We investigate whether implanting a NiTi-based deployable stent in the SCS can effectively reduce IOP with the later goal of augmenting fibrosis.
Methods :
We laser cut microstructures on a NiTi tube and then shape it(500 C) into a deployable stent comprising a flexible tube and an expandable element (Fig. 1b). It can be folded inside a 25 gauge needlme and advanced into SCS using an ab interno surgical approach(Fig. 1c). To eliminate permanent deformation during the deployment, a Finite Element Analysis(FEA) model is created to guide the design(Fig. 1d). A lumped parameter model is derived to predict the IOP reduction induced by the stent. Five perfusion tests are conducted to record the IOP of fresh cadaveric porcine eyes during the deployment by an in-situ pressure transducer. The potential anatomical compliance of the deployable stent is investigated via implantation into huan cadaveric eyes.
Results :
FEA model indicates that the stent has no large deformation during the deployment. Five perfusion tests using fresh cadaveric porcine eyes show an average of 4.53±1.42 mm Hg (Fig. 1e) IOP reduction, which quantitively agrees with the prediction from the analytical model. The OCT images of the deployable stent in human cadaveric eyes showed that the device could be located in the desired position and adapted to the surrounding tissues (Fig. 1f).
Conclusions :
By designing the macro and microstructure of a nitinol stent, an adaptable and expandable stent can be deployed into the SCS. It can be positioned stably inside the SCS, separating the tissues to potentially support a subconjunctival bleb and reducing IOP in the long term. This new deployable MIGS stent paves the way for further innovation in this domain to work towards an efficacious long-term minimally invasive solution to glaucoma treatment.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.