Vitrectomy and fluid-gas exchange was performed in 29 eyes treated with 5 % C3F8 and 1 week of prone positioning , 30 eyes treated with 10 % C3F8 and 2 weeks of prone positioning , and 90 eyes treated with 16 % C3F8 and 2 weeks of prone positioning 90 % of time , followed by 2 weeks of prone positioning 50 % of time .
