A reversible thermosensitive adhesive for retinal implants: in vivo experience with plasma-deposited poly(N-isopropyl acrylamide).
OBJECTIVE
To study the in vivo effects of a thermosensitive retinal adhesive, plasma-polymerized N-isopropyl acrylamide (ppNIPAM), in rabbit eyes.


METHODS
Parylene C(poly(monochloro-p-xylylene)) (20 microm) and poly(dimethyl siloxane) (PDMS) (> or =200 microm) coated with ppNIPAM were used as implant materials. Following pars plana vitrectomy (PPV), ppNIPAM coated parylene (n = 3) and PDMS (n = 3) implants were inserted over the retina in six rabbits. Baseline and follow-up imaging (color fundus photographs, fluorescein angiography, and optic coherence tomography [OCT]) and electroretinogram recordings were performed. Histologic evaluation was performed following enucleation at 6 weeks.


RESULTS
Intraoperative retinal adhesion occurred in all eyes with ppNIPAM coated parylene and PDMS implants. Two eyes developed retinal tears during the implantation procedure and the ppNIPAM coated implants closed the retinal tears successfully preventing retinal detachment. OCT findings confirmed the retinal adhesion in all eyes. Four weeks after implantation one parylene and one PDMS implant detached partly from the retinal surface. Histology showed mild changes at the outer retinal segments. There was no evidence of ocular toxicity and inflammation. None of the eyes that had an implant covering the retinal tear developed a retinal detachment but had some inflammatory changes around the implants.


CONCLUSIONS
ppNIPAM coated implants may provide retinal adhesion in vivo without measurable ocular toxicity in the short term. Covering a retinal tear, the ppNIPAM coated implants may prevent retinal detachment.
Doheny Eye Institute, University of Southern California, Los Angeles, CA, USA. mtunc@isbank.net.tr
Murat
M
Tunc
Mark
M
Humayun
Xuanhong
X
Cheng
Buddy D
BD
Ratner
D000178:Acrylamides; D000180:Acrylic Resins; D000818:Animals; D004129:Dimethylpolysiloxanes; D004596:Electroretinography; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D006358:Hot Temperature; D008297:Male; D009757:Nylons; D011108:Polymers; D011184:Postoperative Period; D019736:Prostheses and Implants / Q000009:adverse effects; D019919:Prosthesis Implantation / Q000009:adverse effects; D011817:Rabbits; D012160:Retina / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D012163:Retinal Detachment / Q000517:prevention & control; D012167:Retinal Perforations / Q000209:etiology / Q000601:surgery; D013997:Time Factors; D014014:Tissue Adhesives / Q000009:adverse effects / Q000737:chemistry* / Q000627:therapeutic use*; D041623:Tomography, Optical Coherence; D014821:Vitrectomy / Q000379:methods; D014992:Xylenes
D000178:Acrylamides; D000180:Acrylic Resins; D004129:Dimethylpolysiloxanes; D009757:Nylons; D011108:Polymers; D014014:Tissue Adhesives; D014992:Xylenes; C085707:poly(dimethylsiloxane)-polyamide copolymer; C052970:poly-N-isopropylacrylamide; C011055:parylene