Injectable silicone rubber for ocular implantation after evisceration

Objective
To investigate the usefulness of addition type liquid silicone rubber (ATLSR) as injectable implant after evisceration to maintain the eyeball volume in an animal experiment.
Methods
Twelve adult New Zealand white rabbits were included. One eye of each rabbit was randomly selected for evisceration with the fellow eye as control. ATLSR was injected to fill the eyeball socket after evisceration. In vivo observation and photographs were performed up to 24 weeks post-op. Two rabbits were sacrificed respectively at post-operative week 1, 2, 4, 8, 12 and 24. After enucleation, the vertical, horizontal and sagittal diameters of the experimental eyeballs were measured and compared with the control eyes. Histopathological studies were performed to evaluate signs of inflammation.
Results
Cornea remained clear throughout the observation period despite mild epithelial edema and neovascularization. Compared to the control eyes, the experimental eyes were significantly smaller in vertical diameter (17.00±1.17 vs. 17.54±1.11 mm, P<0.001), but larger in sagittal diameter (16.85±1.48 vs. 16.40±1.38 mm, P = 0.008), and had no significant difference in horizontal diameter (17.49±1.53 vs. 17.64±1.21 mm, P = 0.34). Postoperative inflammation was observed at one week after surgery, which peaked at 2–3 weeks, then regressed gradually. At week 12 and week 24, most of the inflammatory cells disappeared with some residual plasma cells and eosinophils.
Conclusion
Injectable addition type silicon rubber may be a good choice for ocular implantation after evisceration, maintaining eyeball volume and cosmetically satisfactory when compared to the fellow eye. Spontaneous regression of inflammation implied good biocompatibility for at least 24 weeks.

研究目的：本动物实验旨在探究添加型液体硅橡胶（addition type liquid silicone rubber, ATLSR）作为眼球内容剜除术后可注射植入物，在维持眼球容积方面的应用价值。
研究方法：选取12只成年新西兰大白兔，随机选取每只家兔的1只眼行眼球内容剜除术，对侧眼作为对照。剜除术后向眼窝内注射ATLSR以填充缺损。术后直至24周期间，定期开展体内观察与眼部影像拍摄。分别于术后1、2、4、8、12及24周各处死2只家兔。处死摘除眼球后，测量实验组眼球的垂直径、水平径及矢状径，并与对照眼进行对比。同时开展组织病理学检查，以评估炎症反应征象。
研究结果：整个观察周期内，角膜均保持透明，仅伴随轻度上皮水肿与新生血管形成。与对照眼相比，实验组眼球垂直径显著更小（17.00±1.17 vs 17.54±1.11 mm，P<0.001），矢状径显著更大（16.85±1.48 vs 16.40±1.38 mm，P=0.008），而水平径无显著统计学差异（17.49±1.53 vs 17.64±1.21 mm，P=0.34）。术后1周即可观察到炎症反应，于2~3周达到峰值，随后逐渐消退。至术后12周及24周时，绝大多数炎症细胞已消失，仅残留少量浆细胞与嗜酸性粒细胞。
研究结论：可注射型添加型液体硅橡胶可作为眼球内容剜除术后眼部植入的优质选择，相较于对侧眼，其可有效维持眼球容积且外观效果理想。炎症反应可自发消退，表明该材料至少在24周内具备良好的生物相容性。