Effects of UV Crosslinking under High Temperature on the Refractive Indices and Aggregation Structures of Benzophenone-containing Polyimides

For controlling the optical and thermal properties of photo-sensitive benzophenone (BP)-containing polyimides (PIs), an attempt was made to fix the dense polymer chain packing induced by high pressure using intermolecular crosslinking reactions. The effects of temperature and pressure during UV irradiation on the reaction rates of photo-crosslinking and refractive indices were evaluated. After UV irradiation at ambient temperature and pressure, refractive indices of the PIs increased due to the densification of chain packing. The degree of crosslinking was further increased with increasing the irradiation temperature. The PI films irradiated at 400 MPa exhibited higher refractive indices than those irradiated at 0.1 MPa, despite the nearly identical reaction rates. The fluorescence intensities of the PIs irradiated at 400 MPa showed smaller dependence on the pressure than those irradiated at 0.1 MPa, which indicates that the dense chain packing formed under high pressures was partially and effectively fixed by UV irradiation. The increase in refractive indices of the PIs irradiated at elevated pressures is attributable to the densification of aggregation structures, which was controllable by pressure under UV irradiation

Crystalline lens changes in porcine eyes with implanted phakic IOL (ICL) with a central hole

BACKGROUND: We calculated the smallest diameter of a hole in the center of the optic at which the optical character of a phakic IOL (ICL) may be maintained. The changes induced in the aqueous humor dynamics and the pathology of cataract development with such a hole were investigated. METHODS: A simulation was performed using ZEMAX software to calculate the hole diameter that makes possible the maintenance of a stable optical character of a phakic IOL. After a hole of calculated diameter was trepanned in the center of the optic of the ICL, the latter was implanted into one eye of a 5-month-old minipig, and an unperforated ICL into the other. The postoperative course was observed for 3 months. Then, Evans blue was injected into the vitreous body under general anesthesia to stain the anterior capsule of the crystalline lens. Within 30 min, the eye was enucleated and the tissues removed were fixed. RESULTS: The MTF of the perforated ICL (hole diameter, 1.0 mm) in the center of the optic resembled that of the unperforated ICL. In all cases with non-perforated ICLs, subcapsular turbidity developed, but no staining caused by EB was observed in the anterior capsule. On the other hand, the anterior capsules of the eyes fitted with ICLs with a 1.0-mm hole were stained, but exhibited no turbidity. CONCLUSION: An ICL with a central hole of diameter 1.0 mm in the optic is similar to an unperforated ICL. The size of the hole influenced the aqueous humor dynamics and increased the aqueous humor perfusion volume over the entire anterior surface of the crystalline lens. The possibility of preventing cataracts was therefore suggested