Topographic distribution of prednisolone in the lens after organ culture.

Topographic distribution of prednisolone in the lens after organ culture was investigated. Freshly enucleated pig lenses were divided into two groups; the complete vitreous was removed from the lenses in group A, and the adherent parts of the vitreous were left in group B. Groups A and B were each divided into two subgroups which were separated according to drug application: two groups underwent drug application by a divided chamber (Iwata, 1982, DC) and two groups by a closed chamber. The incubation medium was TCM-199 with 2 micrograms/ml prednisolone, and the incubation was performed for 8 h. In order to know the participation of the vitreous in drug penetration into the lens, prednisolone was applied by a divided chamber from the anterior or posterior side, with or without vitreous, and incubated for 4 h as a first incubation. A secondary incubation was performed for another 4 h with a medium that did not contain prednisolone. After the lens incubation, the lenses were separated into single lens layers, and the drug concentration of each lens layer was measured by high performance liquid chromatography. The highest prednisolone concentration in the lens was detected by a closed chamber in the equatorial part followed by the posterior cortex, anterior cortex and nucleus. There were no significant differences in drug concentration due to the direction of drug application or the absence or presence of vitreous. The prednisolone distribution pattern in the lens by DC depended on the direction from which the drug was applied. The highest drug concentrations were detected in the lens cortex of the drug-applied side followed by the equator. No drug was detected in the side of the lens opposite the drug-applied side or in the nucleus. When a drug was applied from the posterior lens side, the presence of the vitreous made a big difference in the amount of drug penetration. The comparison of drug concentration between the absence or presence of the vitreous after secondary incubation in a medium that did not contain prednisolone indicated that the vitreous participates in the drug kinetics of the lens. The experiments suggest that while prednisolone penetration into the posterior lens part is small compared to that of the anterior part, when the steroid penetrated into the posterior part it remained there for a long period.