Injectability of silicone oil-based tamponade agents.

BACKGROUND/AIMS: High viscosity silicone oils are used as tamponade agents to increase the resistance to emulsification; however, this makes the oils more difficult to inject. Increasing the extensional viscosity is one way to reduce emulsification. This study aimed to evaluate how silicone oils with increased extensional viscosity behave in terms of their ease of injection. METHODS: The shear viscosity and the length of time taken to inject 9 ml of Siluron 1000, Siluron 2000, Siluron 5000, SiliconMate, a 56/44 w/w blend of Siluron 1000/Siluron 5000 (Blend A) and a 90/10 w/w blend of Siluron 1000/PDMS 423kDa molecular weight (Blend B) were examined. RESULTS: The shear viscosity of Siluron 1000, Siluron 2000 and Siluron 5000 were within the expected ranges. The shear viscosity of Blend A was 2283 mPa s, Blend B was 4710 mPa s and SiliconMate was 995.3 mPa s. Siluron 1000 and SiliconMate had the shortest injection times as expected due to their lower shear viscosities. Comparison of Siluron 2000 and Blend A demonstrated that Siluron 2000 was easier to inject. Similarly, Blend B was easier to inject than Siluron 5000. CONCLUSION: Silicone oil blends containing small percentages of a high molecular weight additive are easier to inject than single grade oils of the equivalent shear viscosity.

Vitreoretinal interface changes in acute-onset postoperative endophthalmitis.

BACKGROUND: The aim of this study was to assess the significance of different clinical appearances of the vitreoretinal interface in the surgical management of acute postoperative endophthalmitis. PATIENTS AND METHODS: 22 patients underwent vitrectomy and were divided intraoperatively in 3 groups according to the degree of vitreoretinal interface changes: 10 patients had white infiltrates in the vitreous cortex but no retinal hemorrhages (group A), eight patients had white infiltrates in the vitreous cortex and retinal hemorrhages (group B) and four patients had advanced vitreous opacification, strong vitreoretinal adhesions and retinal hemorrhages (group C). In group A vitrectomy was performed and the vitreous cortex was removed cautiously, while in groups B and C the vitreous cortex was not removed in the first procedure. RESULTS: Visual acuity improved in 14 patients, remained stable in 2 patients and deteriorated in 6 patients. The visual prognosis was better in group A. None of the cases was complicated with retinal detachment following vitrectomy, but in groups B and C 37.5 % and 50 % of the patients, respectively, went into phthisis. CONCLUSIONS: Intraoperative assessment of the vitreoretinal interface insult in acute postoperative endophthalmitis contributes to an optimal surgical management, and it also has a prognostic value.