Study	Reason for exclusion
Bloomgarden 1999	Review article.
Desai 2007	Review article.
Gincherman 1982	The aim of this article was to study haemocoagulation in 78 patients with diabetes mellitus during the treatment of diabetic retinopathy with antiaggregating and haemostatic drugs.
Gol'tseva 1983	Groups from the article are different of those from the protocol.
Ivanisevic 1994	Review article.
Iwafune 1980	The aim of this study was to evaluate the effect of pentoxyfilline given orally to patients with retinal haemorrhage caused by disturbances of retinal circulation, i.e. branch and/or total obstruction of the central retinal vein, obstruction of the central retinal artery, diabetic retinopathy and polycytaemic retinopathy.
Katznelson 1980	The aim of this article was to evaluate the effect of pentoxyfilline on the oxygenation of the anterior chamber humour and the bioelectrical activity of the retina.
McCarty 1998	Review article.
Parikh 2004	Review article.
Polunin 1993	Article is different from the reference.
Radfar 2005	Groups from the article are different of those from the protocol.
Saldan 1984	The aim of this article was to reveal the role of coagulative shift of blood in pathogenesis of diabetic retinopathy.
Schubotz 1975	No RCT, no investigation of diabetic retinopathy.
Schubotz 1975a	No RCT, no investigation of diabetic retinopathy.
Solerte 1985	The aim of this article was to evaluate erythrocyte filtrability, reduction in fibrinogen levels, proteinuria and albumin excretion rate.
Sonkin 1993	The aim of this study was to determine if oral pentoxyfilline would improve retinal microvascular haemodynamics and blood rheology in patients with diabetes.
Wroe 2001	Conference report.