“…Incomplete outcome data-Of the 33 studies, investigators of 17 studies reported few or no losses to follow-up, resulting in our assessment of them to be at low risk of attrition bias: four of six trials of Ex-PRESS (Dahan 2012;De Jong 2009;Netland 2014;Wagschal 2013), five of eight studies for Ologen (Cillino 2011;Marey 2013;Papaconstantinou 2010;Rosentreter 2010;Rosentreter 2014), six of 18 studies for amniotic membrane (Cai 2012;Eliezer 2006;Ji 2013;Khairy 2015;Liu 2009;Stavrakas 2012), one study for E-PTFE (Cillino 2008), and one study for Gelfilm (Birt 1998). Four studies had a relatively large percentage of losses to follow-up (> 10%) and we assessed the risk of attrition bias to be high for these studies (Bruno 2008;Cho 2013;Senthil 2013;Sheha 2008).…”