PURPOSE. Successful intraocular lens procedures, that is, implantation of accommodating intraocular lenses (A-IOL), require firm engagement of the IOL haptics to the capsular bag. We evaluated the use of photochemical bonding to engage IOL materials to the capsular bag.METHODS. Freshly enucleated eyes of New Zealand rabbits were used in two types of photobonding experiments using Rose Bengal (RB) photoinitiation and green light (532-nm) irradiation. First, RB-stained capsular bag strips were photobonded ex vivo to IOL polymer [poly(2-hydroxyethyl methacrylate) pHEMA] strips in an atmosphere of air and of nitrogen. Second, IOLs were implanted intracapsularly and photobonded intraocularly. Irradiation times were between 30 and 180 seconds, and laser irradiance was between 0.25 and 0.65 W/cm 2 . The strength of the bonding was tested using a custom-developed uniaxial extensiometry system and the breakage load (the load that caused breakage per bonded area) was calculated.RESULTS. The breakage load of ex vivo capsule-pHEMA bonds increased exponentially with irradiation time, using 0.45 W/cm 2 . In air, the average breakage load across all conditions was 1 g/mm 2 and 1.6 times lower than that in a nitrogen atmosphere. Intraocularly, RB-stained IOLs were strongly photobonded to the capsule bag with breakage loads > 0.8 g/mm 2 .CONCLUSIONS. Breakage of the photobonded linkage between IOL material and capsular bag required loads substantially greater than the maximum force of ciliary muscle, suggesting that this technology may introduce a new paradigm for engagement of A-IOLs. The bonding produced in air was stronger than that in nitrogen atmosphere, suggesting that oxygen is involved in the chemical mechanism for photobonding.
A study of Ba(2)NaNb(5)O(15) and LiNbO(3) crystals with periodic ferroelectric domain structures using the scanning near field optical microscopy technique is reported. Optical contrast is observed in the regions of ferroelectric domain boundaries and it is analysed using beam propagation method modelling. This reveals that the optical contrast, a consequence of changes in the refractive index, is not due to variation of the waveguide-coupling efficiency, and supports the hypothesis that it is associated with the domain array, which is related to the size of the domain.
Multilayers of MgF2 and Sb2S3 have been obtained by physical vapour deposition on glass substrates. Changes in the optical and structural properties have been studied as a function of annealing temperature and the number of layers. A drastic variation in optical transmission, microstrain and grain size is observed at a temperature near 225 °C. A comparison of the material properties of multilayers and a monolayer is carried out.
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