Human vitreal prostaglandin levels and proliferative diabetic retinopathy

To determine the association of prostaglandins E1 (PGE1), E2 (PGE2), and F2-alpha (PGF2-alpha) with proliferative diabetic retinopathy (PDR) in human vitreous.

We collected human vitreous samples from eyes undergoing pars plana vitrectomy for proliferative diabetic retinopathy with vitreous hemorrhage (N=13) and for other reasons including macular gliosis and Stage IV idiopathic macular holes (N=7). Vitreal prostaglandins E1, E2, and F2-alpha were measured by radioimmunoassay.

Eyes with PDR had significantly lower vitreal levels of PGE1 (74.77 pg/ml +/- 15.70) compared to those without PDR (91.86 pg/ml +/- 13.36) (p=0.025) using t-test analysis. Eyes with PDR also had significantly lower levels of PGE2 (127.52 pg/ml +/- 70.52) compared to those eyes without PDR (194.43 pg/ml +/- 57.10) (p=0.045). In addition, eyes with PDR had significantly lower levels of PGF2-alpha (34.62 pg/ml +/- 11.56) compared to those eyes without PDR (51.43 pg/ml +/- 18.44) (p=0.021). Panretinal photocoagulation in diabetic eyes did not have an effect on vitreal concentrations of PGE1 (p=0.588). PGE2 (p=0.460) and PGF2-alpha (p=0.351), but sample size was too small.

Diabetic eyes with PDR had significantly lower vitreal levels of PGE1, PGE2 and PGF2-alpha compared to controls consistent with decreased production of these prostaglandins by the endothelial cells of diabetic eyes. Laser treatment did not appear to have a significant effect on vitreal concentrations of these prostaglandins, but sample size was small. The lower concentration of these vasodilatory prostaglandins may reflect the vasculature's inability to produce these substances and the vasoconstrictive state of the end-stage diabetic eye with PDR.