The permeability of the blood retinal barrier (PBa~) and the diffusion coefficient into the anterior chamber (kd) in 20 insulin dependent (ID) and in 11 non-insulin dependent (NID) diabetics with various degrees of retinopathy were determined by fluorophotometry with a 25% accuracy. The difference of PBRB and the kd values between the NID and the ID patients was not significant (p > 0.05 and p > 0.22).
The mean P~rtB and the mean k d values differed significantly from those of a healthy population (p < 0.0013 and p = 0.025). A significant correlation was established between PBrt~ and diabetes duration (r = 0.55; p < 0.01) but not between PBRB or ka values and metabolic control (HbA1) (p > 0.5) or creatinine clearance (p > 0.5). The time integrals of unbound plasma fluorescein in the diabetics between the time of injection and 1 hour later were comparable with those of healthy controls.
The difference between the mean PBRB value of diabetics with advanced retinopathy and that of a healthy population was significant (p < 0.003) but the difference for the mean values of diabetics with no or minimal background retinopathy was not (p > 0.2), indicating that PBRB values do not increase to an abnormal level while signs of diabetic retinopathy are absent on fluorescein angiography.