Abstract
Abstract: :
Purpose : To assess corticosteroid induced impairment of fluorescein transport in retinal pigment epithelium (RPE) preparations. The occurence of central serous chorioretinopathy has been linked to corticosteroid treatment. Previous electrophysiological results in vitro seemed to indicate that corticosteroids could have a inhibitory effect on fluid absorption resulting in a relative break-down of the blood-retinal barrier (BRB). In patients with central serous chorioretinopathy, the integrity of the BRB is evaluated by fluorescein angiography. Methods : Bovine RPE-choroid preparations were mounted in Ussing type chambers allowing to monitor continuously the electrophysiological parameters. Fluorescence intensity was measured every 15 minutes for 120 minutes on either apical (retinal) or basolateral (choroidal) side of the preparation after administration of fluorescein on the opposite side. For each experiment, two preparations were obtained from the same eye, in one hydrocortisone (HC) 10-4 was administered on the apical side at t=0, the control preparation received the vehicle. Results : When fluorescein was applied on the basolateral side of the preparation, fluorescein intensity increased with time on the apical side in the RPE preparation treated with HC, whereas fluorescence intensity remained low in controls. When fluorescein was applied on the apical side of the preparation, fluorescence intensity on the basolateral side increased with time in both HC treated and control preparations. However, the intensity was significantly lower in the HC treated preparations. Conclusions : Corticosteroids appear to induce fluorescein accumulation in the subretinal space. Passive diffusion of fluorescein from the choriocapillaris to the retina is not counterbalanced by active transport in the opposite direction.
Keywords: retinal pigment epithelium • corticosteroids • pump/barrier function