Rapid and continuous fluctuations in ocular focus are known to occur when the eye views a stationary target. The advent of high-speed infra-red optometers has established that these microfluctuations of ocular accommodation have two dominant components: low frequency of less than 0.6 Hz and high frequency between 1.0-2.3Hz. Although the retinal image blur associated with microfluctuations has the potential to guide and maintain optimum accommodation levels, there is no consensus with regard to the respective contribution of each of the dominant frequency components. Using a newly-designed measurement and recording system we show that, when viewing a stationary target located at 25cm, individuals exhibit little variation in the frequency of low frequency components but significant variation in high frequency components. Simultaneous measurements of ocular accommodation and systemic arterial pulse demonstrate that the variation in high frequency component is significantly correlated with arterial pulse frequency. Since control experiments indicate that the microfluctuations are derived from activity of the crystalline lens our observations could provide the basis for a non-invasive method of assessing the effects of arterial pulse on ciliary body/choroidal vasculature, the vitreous/lens interface and intraocular pressure. Further, it is feasible that under certain conditions an abnormal increase in the magnitude of arterial pulse may affect the aggregate nature of accommodative microfluctuations to an extent that disrupts the normal control processes maintaining optimum retinal contrast during sustained near vision.

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The complex cis-[Os(bpy)2(CO)H]+ (bpy is 2,2'-bipyridine) has been found to be an electrocatalyst for the reduction of C02 in CH$N containing 0.1 M tetra-n-butylammonium hexafluorophosphate at glassy carbon or Pt electrodes. Under anhydrous conditions CO is the dominant product, but addition of water results in up to 22% formate anion. Kinetic parameters derived by digital simulation of cyclic voltammograms under electrocatalytic conditions are consistent with a rate-determining associative step (kl) in which C02 undergoes a reaction with the direduced complex, [Os(bpy)z(CO)H]-, to form an intermediate. This intermediate either gives CO or a second intermediate which is a source of CO or formate by competitive pathways that follow the rate-determining step(s). On the basis of the results of isotopic labeling studies, neither the bound CO nor H-groups are involved in the reduction of CO1. The kinetics of reduction of C02 by the twice-reduced complexes ~is-[M(bpy)~(CO)R]-(M = Os, R = H, Me, Ph; M = Ru, R =