Vitreous fluorophotometry (VFP) was performed for myopic eyes induced by unilateral eyelid suturing of six young cynomolgus monkeys in order to study the permeability of the blood-ocular barrier. The eyelid fusion was temporarily cut and opened at about five-month intervals, and the dioptric power and axial length of test and control eyes were measured. VFP was carried out before and after intravenous injections of fluorescein-Na. The inward permeability of the blood-retinal barrier (P(in)) was estimated by our computer simulation method, and the index of permeability of the blood-aqueous barrier (AQ) was also obtained. Significant prolongation of the length of the vitreous cavity was first seen 10 months after suturing, with the degree of myopia progressing subsequently. P(in) and AQ values increased as myopia progressed: significant increases were observed at 10 and 16 months after suturing, respectively. These results indicate a close relationship between the occurrence and progress of myopia and increased permeability of the blood-ocular barrier.