Ocular reactivity of bacterial endotoxin in various media

Even a small quantity injected intracameral leads to visible reactions

Silver Spring – mechentel news – Inflammation was seen after intracameral injection of as little as 0.02 and 0.08 endotoxin units (EU) in ophthalmic viscosurgical device (OVD) and Dulbecco’s phosphatebuffered saline (DPBS) eyes, respectively, so S.Y. Buchen et al. from Oakridge Institute for Science and Education, Silver Spring, USA. This study was performed using 75 rabbits to evaluate the ocular reactivity to bacterial endotoxin contained in DPB, a cohesive OVD, and a dispersive OVD. For each test material, 25 rabbits were randomized into 5 groups and were exposed to the test material containing 0.75 endotoxin units EU, 0.25 EU, 0.08 EU, and 0.02 EU of endotoxin or the vehicle control. The rabbits in each group received bilateral intracameral injection of 0.05 ml of the same test material. All eyes were examined by slit-lamp biomicroscopy at baseline, 3, 6, 9, 24, 48, and 72 hours after injection. At 24 and 72 hours, slitlamp biomicroscopy (and additionally indirect ophthalmoscopy) was performed through dilated pupils. Corneal clouding, anterior chamber (AC ) flare, cells and fibrin, vitreous haze and cells, cells and fibrin on lens surface, lens opacities, and onset time were the main outcome measures. The inflammation seen after exposure to the 3 endotoxin-spiked materials followed the same general time course. Anterior chamber cells, flare, iris hyperemia, and conjunctival congestion were seen as early as 3 hours. They started to diminish after 6 hours (DPBS eyes) and 9 hours (OVDs) and were not detectable at 48 and 72 hours, respectively. The AC inflammation was more severe in the OVD eyes than in the DPBS eyes. Anterior chamber fibrin was seen in the OVD eyes only, which persisted through 72 hours in many eyes. A trend toward a dose-response relationship was seen for AC cells and flare and the presence of cells and fibrin on the lens surface in all 3 treatment groups in the first 24 hours. Observed responses to intracamerally injected endotoxin in OVDs were more severe and of longer duration than those in aqueous medium, so the scientists in the July issue 2012 of the journal Ophthalmology.

Authors: Buchen SY, Calogero D, Hilmantel G, Eydelman MB. Correspondence: Food and Drug Administration, Oak Ridge Institute for Science and Education contractor, Silver Spring, Maryland 20993-0002, USA. Study: Rabbit ocular reactivity to bacterial endotoxin contained in aqueous solution and ophthalmic viscosurgical devices. Source: Ophthalmology. 2012 Jul;119(7):e4-e10. doi: 10.1016/j.ophtha. 2012.04.006. Epub 2012 May 11. Web: http://www.aaojournal.org/article/S0161-6420(12)00328-4/abstract