Changes in blood-retinal barrier permeability in form deprivation myopia in tree shrews

To study the correlation between blood-retinal barrier (BRB) permeability a nd development of form deprivation (FD) myopia, FD was induced in tree shre ws. The refractive error and the axial dimensions of the optical elements w ere measured. Ocular fluorescence was measured before and after fluorescein -Na injection. The inward permeability (P-in) of the BRB was measured befor e and 15, 301 and 45 days after FD was induced. FD eyes became significantl y myopic 15 days after FD was induced (P < 0.01), and myopia progressed 45 days after FD was induced compared with untreated controls. Neither anterio r chamber length nor lens thickness changed significantly. The vitreous cha mber in FD eyes, however, was significantly elongated from 15 days after FD was induced (P < 0.01) compared with controls. The P-in ratio (P-in [FD ey e]/P-in [untreated control]), increased significantly 45 days after FD was induced (P < 0.05). In FD myopia in tree shrews, the BRB permeability incre ases abnormally. Impaired BRB function might be a secondary effect of myopi a development rather than the cause of myopia. (C) 2000 Elsevier Science Lt d. All rights reserved.