Lysosomal trapping at the blood–retinal barrier (BRB) was investigated through quinacrine and fluorescence-labeled verapamil (EFV) uptake. Quinacrine uptake by conditionally immortalized rat retinal capillary endothelial (TR-iBRB2) cells suggested saturable and non-saturable transport processes in the inner BRB. The reduction of quinacrine uptake by bafilomycin A1 suggested quinacrine distribution to the acidic intracellular compartments of the inner BRB, and this notion was also supported in confocal microscopy. In the study using the lysosome-enriched fraction of TR-iBRB2 cells, quinacrine uptake was inhibited by bafilomycin A1, suggesting the lysosomal trapping of quinacrine in the inner BRB. Pyrilamine, clonidine, and nicotine had no effect on quinacrine uptake, suggesting the minor role of lysosomal trapping in their transport across the inner BRB. Bafilomycin A1 had no effect on EFV uptake, and lysosomal trapping driven by the acidic interior pH was suggested as a minor mechanism for EFV transport in the inner BRB. The minor contribution of lysosomal trapping was supported by the difference in inhibitory profiles between EFV and quinacrine uptakes. Similar findings were observed in the outer BRB study with the fraction of conditionally immortalized rat retinal pigment epithelial (RPE-J) cells. These results suggest the usefulness of lysosome-enriched fractions in studying lysosomal trapping at the BRB.

Purpose: To differentiate superior segmental optic hypoplasia (SSOH) from normal-tension glaucoma (NTG) with inferior visual field defects only. Methods Eighteen eyes with SSOH (SSOH group) and 19 eyes with NTG (NTG group) were examined by optical coherence tomography (OCT), Heidelberg retina tomography (Heidelberg Retinal Tomograph II, HRT II) and standard automated perimetry.Results: Retinal nerve fiber layer thickness (RNFLT) based on OCT measurements was significantly reduced (thinner) in the superior to superonasal sectors and significantly greater (thicker) in the inferotemporal sector in the SSOH group than in the NTG group. The cup was significantly smaller and the rim significantly larger in the superotemporal and temporal sectors in the SSOH group than in the NTG group based on HRT II measurements. The greatest area under the receiver operating characteristic curve for discrimination of SSOH from NTG by OCT and HRT II was for the RNFLT ratio of 1 +2 o'clock/10 +11 o'clock (0.985) and for the ratio of the superonasal to superotemporal sector of rim to disc area ratio and cup to disc area ratio (0.955), respectively. The frequent location of the inferior visual field defects corresponded to the difference in structural changes in both groups.Conclusions: Comparison of the superonasal to superotemporal sectors by OCT and HRT II were useful in differentiating SSOH from NTG with only inferior visual field defects.