Reversible retina implants glue impresses

October 23, 2007

A thermosensitive glue for retinal implants provides an effective in vitro retinal adhesion that is completely reversible by lowering the temperature.

A thermosensitive glue for retinal implants provides an effective in vitro retinal adhesion that is completely reversible by lowering the temperature, according to a report published in the September issue of Retina Journal.

Murat Tunc from Abant Izzet Baysal University, Turkey and colleagues conducted a study to determine the in vitro effects of plasma polymerized N-isopropyl acrylamide (pNIPAM) coating for thermally controllable adhesion to retinal tissue.

Polyimide (50 µm), parylene C (20 µm) and polydimethyl siloxane (PDMS [200 µm]) were coated with pNIPAM and used as implant materials to test retinal adhesion in enucleated pig eyes. Following preparation of the implant materials (n=5) and retina, the researchers held the implants over the retinal tissue at 22°C and gradually increased the temperature of the water bath over a 15-minute period and monitored the adhesion. The adhesive force was measured using a traction test that involved a suture attached to the implant and a strain gauge. The authors also checked the reversibility of the adhesion by lowering the temperature of the water bath.

The results demonstrated that there was no retinal adhesion at room temperature (22°C), however, adhesion developed strongly within 60 seconds of reaching the critical temperature (≥32°C). The adhesion remained when tractional forces of 98 mN and 148 mN were applied between 32 and 38°C. When the temperature was lowered back to 22°C by irrigation with cold BSS, the implants detached from the retinal surface without the use of tractional force.

This study demonstrates that pNIPAM can provide effective retinal adhesion, which is completely reversible by lowering the temperature of the physiologic medium.