1445 Growth factor levels in the diabetic vitreous: Correlation with type of diabetes and neovascular activity

Purpose. To determine growth factor levels in individual vitrectomy samples from insulin-d ependent and non-insulin dependent diabetics (IDDM & NIDDM) and to correlate such levels with a) the type of diabetes and b) neovascular activity. Me&m! Over 70 vitreous gel samples wem obtained from diabetic patients with proliferative retinopathy and non-diabetic (“control”) patients undergoing vitrectomy. Levels of bFGF, IGF-I, EGF, TGF+Z and insulii were determined by radioimmunoassay. IGF-I binding, protein levels were assessed by laser densitometry of Western ligand blots. RmdtF. bFGF levels were significantly greater in vitreous samples from NIDDM patients than either IDDM OI non-diabetic patients. When subdivided into eyes with active neovascular or inactive fibrotic membranes the highest levels of bFGF were found in NIDDM patients with active membranes. No significant difference in the levels of ~the other growth factors was observed between the NIDDM and non-diabetic group. In the IDDM group, both IGF-I and a 34kDa IGF-BP were elevated compared to the other groups while TGF-p2 levels were greatly reduced. The increase in IGF-I and IGF-BPS, and the decrease in TGF+2, were greatest in patients with active neovascularisation. bFGF and EGF levels were did not differ between the IDDM and non-diabetic groups. Conclwion. In proliferative diabetic rctinopathy there is a correlation between intravitreal growth factors and both disease type (whether IDDM or NIDDM) and disease state (whether active 01 fibrotic).