Inflammatory responses after vitrectomy with vitreous substitutes in a rabbit model

PurposeTo investigate the inflammatory response of current and future potential vitreous substitutes in an experimental in vivo vitrectomy model.MethodsTwenty-five gauge pars plana vitrectomy was performed in the right eye of 60 pigmented rabbits, with subsequent injection of 0.5-1.0 ml of Healaflow (R) (cross-linked hyaluronic acid, n=12), Bio-Alcamid (R) (polyalkylimide, n=8), silicone oil (n=12), or balanced saline solution (BSS, n=28). Postoperative clinical evaluation was performed; and the rabbits were sacrificed at 1 day, 1 week, or 1 month. The eyecups were then examined macroscopically; the retinas sectioned and stained with hematoxylin and eosin (Htx), and immunohistochemically labeled for glial fibrillary acidic protein (GFAP), CD45, galectin-3, CD68, and CD20. Unoperated left eyes from treated animals as well as eyes from untreated animals were used as controls.ResultsVitrectomy without major complications was achieved in 46/60 eyes. The remaining 14 eyes were analyzed separately. One eye developed endophthalmitis after 1 week and was excluded. Eyes treated with Healaflow (R), silicone oil, and BSS had a comparable appearance macroscopically and in Htx-stained sections, whereas Bio-Alcamid (R)-injected eyes exhibited increased macroscopic inflammation and severely affected retinas. GFAP upregulation was present in all treatment groups, most prominent in eyes treated with Bio-Alcamid (R) and silicone oil. Upregulation of CD45 and CD68 in the inner retina and vitreous space was most prominent with Bio-Alcamid (R) treatment, and these eyes together with their silicone oil-treated counterparts also displayed a stronger upregulation of CD20-labeled cells compared with remaining groups. General upregulation of galectin-3, mainly in the inner retina, was found in all groups. In eyes with perioperative complications, labeling of CD45, CD68, and especially GFAP was comparably high.ConclusionsWe here describe differences in the postsurgery inflammatory profiles of existing and potential vitreous substitutes. Bio-Alcamid (R) and silicone oil display severe signs of gliosis and inflammation, whereas Healaflow (R) elicits minimal reactions comparable with BSS, highlighting its potential application as a vitreous substitute in a future clinical setting.