Intraoperative bleeding will be graded in 3 levels: grade 1 is defined as minor bleeding stopped either spontaneously or by transient bottle elevation; grade 2 is defined as moderate bleeding resulting in broad sheaths of clots requiring endodiathermy to the bleeding sites to stop the bleeding; grade 3 is defined as thick clot formation covering half or more of the posterior pole or interfering with the surgical plane. Postoperative preretinal blood will be separated into 3 grades: isolated clots with total area less than 10 disc area and without involvement of the posterior pole (grade1); broad sheaths of clots with total area more than 10 disc area without involving the posterior pole (grade2); broad sheaths of clots with total area more than 10 disc area and with involvement of the posterior pole (grade3). Any noticeable increase of preretinal blood will be defined as recurrent hemorrhage.