Permeability of the blood-retinal barrier and the blood-aqueous barrier in type I diabetes without diabetic retinopathy: simultaneous evaluation with fluorophotometry.

For the evaluation of a possible malfunction of the blood-retinal barrier (BRB) and the blood-aqueous barrier (BAB) in type I diabetes without manifest angiopathy after i.v. injection of sodium fluorescein, the permeability of the BRB (P) and the permeability coefficient of the BAB [P(a)] were simultaneously determined by fluorophotometry in 34 eyes of 34 type-I diabetics [hemoglobin (Hb)A1c = 6.6% +/- 0.9%] without retinopathy whose age ranged from 19 to 38 years (mean, 30.5 +/- 5 years); the diabetes duration was between 5 and 18 years. Fluorescein angiography was performed to exclude nonperfused areas. In all, 34 eyes of 34 healthy volunteers whose age ranged between 23 and 34 years (mean, 28.5 +/- 3.3 years) served as controls; in this group, fluorophotometry was performed twice to evaluate reproducibility. The mean BAB permeability coefficient in diabetics [P(a) = 5.3 +/- 1.8 x 10(-4)/min] was significantly increased (P = 0.00003) as compared with control values [P(a) = 3.7 +/- 0.7 x 10(-4)/min]; BRB permeability in diabetics (P = 3.2 +/- 1.4 x 10(-7) cm/s) was raised, with this elevation being of lower significance (P = 0.019; controls, P = 2.6 +/- 0.7 x 10(-7) cm/s). We found a decrease in BRB permeability depending on diabetes duration (r = -0.15; P = 0.007) that was not significant in the BAB (r = -0.1; P = 0.24). No correlation was found to exist between permeability and hemoglobin (Hb)A1c values either in the BAB or in the BRB. The reproducibility in controls was 9% in BRB determinations and 12% in BAB measurements.(ABSTRACT TRUNCATED AT 250 WORDS)