INTRAVITREAL GROWTH-FACTORS IN PROLIFERATIVE DIABETIC-RETINOPATHY - CORRELATION WITH NEOVASCULAR ACTIVITY AND GLYCEMIC MANAGEMENT

Aim-Many growth factors are implicated in proliferative diabetic retin opathy (PDR). It was decided to test the hypothesis that no one factor is predominant but that a regular profile of levels of different grow th factors might be operating, and that the profile might differ accor ding to whether or not insulin therapy was part of the patient's glyca emic management. The levels of several growth factors in vitrectomy sa mples were therefore determined from diabetic patients with tractional , non-haemorrhagic sequelae of PDR and these levels were correlated wi th (a) each other (growth factor profile), (b) neovascular activity, a nd (c) the method of glycaemic management (insulin treated (TT) or non -insulin treated (NIT)). Methods-72 samples of vitreous were obtained from either diabetic patients with PDR (n = 51) or non-diabetic (contr ol) patients (n = 21). Levels of bFGF, IGF-I, EGF, and insulin were de termined by radioimmunoassay; levels of TGF-beta 2 by ELISA; and level s of IGF-I binding protein by western ligand blotting. The data were a nalysed using appropriate statistics. Results-There was no regular gro wth factor profile. bFGF levels were significantly greater in vitreous from NIT patients compared with TT patients and controls. The highest levels of bFGF were found in NIT patients with actively vascularised membranes. TGF-beta 2 levels were significantly greater in vitreous fr om TT patients compared with NIT patients and controls The highest lev els of TGF-beta 2 were found in IT patients with actively vascularised membranes. IGF-I levels were significantly greater in diabetics (irre spective of insulin treatment) than non-diabetics and the highest leve rs of IGF-I were found in IT patients with actively vascularised membr anes. A 34 kDa IGFBP was the predominant IGFBP identified in vitreous and was found to be elevated in diabetics patients. Conclusion-In PDR there is a correlation between intravitreal growth factor levels and b oth disease state (whether active or fibrotic) and method of glycaemic management.