Alteration of the blood-retinal barrier and vitreous in sickle cell retinopathy

Nineteen eyes with background sickle cell retinopathy, eleven from patients with SC disease, eight from patients with SS disease, and twelve eyes with proliferative sickle cell retinopathy were examined by direct and indirect ophthalmoscopy, slit-lamp, fluorescein angiography and vitreous fluorophotometry. Calculation of the alteration of the blood-retinal barrier (BRB) and estimation of the diffusion coefficients of fluorescein in the vitreous were performed by fluorophotometry. In background sickle cell retinopathy, the results show a normally functioning BRB in the posterior pole. Abnormally increased fluorescence values to the mid-vitreous (peripheral leakage) were found only in 3 of these 19 eyes, at the two-hour examination (all SC patients). Similarly, mid-vitreous fluorescence values at the two-hour examination were 4.19 ± 1.52 ng/ml in eyes of patients with SC disease, compared with 2.65 ± 0.56 ng/ml in eyes of patients with SS disease. All eyes with background sickle cell retinopathy, except one, showed values for the coefficient of diffusion of fluorescein within normal limits, indicating normal vitreous gel structure. In proliferative retinopathy, the mid-vitreous fluorophotometry readings were abnormally increased, correlating well with the extent of the peripheral angiographic changes (neovascularization). The coefficient of diffusion of fluorescein in the vitreous was generally increased in the eyes with proliferative retinopathy (15.0 ± 8.4 × 10^-4cm²/min) in comparison with a mean value of 5.4 ± 1.4 × 10^-4cm²/min in the eyes wi background sickle cell retinopathy, suggesting an alteration of the vitreous structure eyes with proliferative retinopathy. Fluorophotometry is considered a useful tool to follow patients with sickle cell retinopathy by quantitating peripheral retinal vascular leakage.