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Elysa A Brown, Irina Koreen, R. Patrick Yeatts; Evisceration with Injectable Hydrogel Implant. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2782.
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Evisceration with implant is typically performed using solid sphere implants to reconstitute globe volume. Placement of the sphere requires large anterior and posterior scleral incisions. The development of a liquid injectable implant would permit evisceration through a small incision, such as with 20 gauge vitrectomy. The objective of this study was to determine the safety, durability, and biocompatibility of 2.5% polyacrylamide hydrogel as an injectable implant material in evisceration using a rabbit model.
The protocol was approved by the Wake Forest Institutional Animal Care and Use Committee. Thirteen adult New Zealand rabbits underwent small incision cornea-sparing evisceration of one eye with injection of 2.5% polyacrylamide hydrogel implant. Evisceration was performed through an 8 mm scleral incision 2 mm posterior to the limbus. The wound closure was completed, followed by injection of 2.5% polyacrylamide hydrogel using a 23 gauge needle to fill the globe. Rabbits were sacrificed at 2 weeks (n=1), 6 weeks (n=2), 3 months (n=3) and 6 months (n=3) to evaluate the implant volume and host reaction to the implant. Both eyes were enucleated and their anteroposterior, horizontal and vertical diameters were measured. The eviscerated eyes were then fixed in formalin and processed using routine histopathologic methods.
The implant material was generally well tolerated. Extensive vascularization of the implant was noted starting at 6 weeks. There was excellent maintenance of globe volume that did not diminish over time. The relative diameters of the eviscerated eyes compared to control were 94% at two weeks (n=1), 100% at 6 weeks (n=2), 89 ± 6% (mean ± st dev) at 3 months (n=3), and 94 ± 2% at 6 months (n=3).
Based on our findings, injectable 2.5% polyacrylamide hydrogel may provide an alternative to the solid ocular implants currently used as standard of care in ocular evisceration. The implant material was universally well tolerated and maintained appropriate volume in the orbit for six months following surgery. Vascularization of the implant was a surprising but welcome finding, as it decreases the risk of implant infection. Future directions include evaluation of smaller incision evisceration techniques utilizing vitrectomy equipment for fragmentation and removal of ocular contents.
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