• Written By: Jennifer I. Lim, MD
    Retina/Vitreous

    The authors of a recent study in Retina nicely present the in vitro effects of a plasma polymerized N-isopropyl acrylamide (pNIPAM) coating for thermally controllable adhesion to retinal tissue.
     
    I found this article of high interest because it presents a substance that will allow for more widespread use of devices within the eye. It may allow us to bridge the gap between "science fiction" and reality. The potential applications are protean – biomimetic devices, drug delivery.
     
    Researchers used polyimide (50 [mu]m), parylene C [poly(monochloro-p-xylylene)] (20 [mu]m), and poly(dimethyl siloxane) (PDMS) (200 [mu]m) coated with pNIPAM as implant materials to test retinal adhesion in enucleated pig eyes.
     
    Following preparation of the implant materials and retina, the authors held the implants over the retinal tissue at 22 C and gradually increased the temperature of the water bath within 15 minutes. While increasing the temperature, the authors monitored the adhesion with the retina and pNIPAM coated implant. The authors measured the adhesive force by a traction test using a suture attached to the implant and a strain gauge. Then the authors checked the reversibility of the adhesion by lowering the temperature of the water bath.
     
    They conclude that pNIPAM provides effective in vitro retinal adhesion between 32 C and 38 C, and that this adhesion is completely reversible by lowering the temperature of the physiologic medium.