Post-cataract eye drops can be avoided by depot steroid injections.

There are over 400 000 cataract operations now being performed annually in the UK. With the majority of those patients being older people, comorbidities such as dementia or arthritis can prevent patients putting in their own post-operative eye drops. Where there is a lack of family or other support, district nursing services are often called upon to administer these eye drops, which are typically prescribed four times a day for 4 weeks, thus potentially totalling 112 visits for drop instillation per patient. To reduce the burden of these post-operative eye drops on district nursing services, administration of an intra-operative sub-Tenon's depot steroid injection is possible for cataract patients who then do not require any post-operative drop instillation. As a trial of this practice, 16 such patients were injected in one year, thus providing a reduction of 1792 in the number of visits requested. Taking an estimated cost of each district nurse visit of £38, this shift in practice potentially saved more than £68 000; the additional cost of the injection over the cost of eye drops was just £8.80 for the year. This practice presents an opportunity to protect valuable community nursing resources, but advocacy for change in practice would be needed with secondary care, or via commissioners.

Solution-state conformational ensemble of a hexameric porphyrin array characterized using molecular dynamics and X-ray scattering.

Solution-phase X-ray scattering measurements in combination with coordinate-based modeling have been used to characterize the conformational ensemble of a hexameric, diphenylethyne-linked porphyrin array in solution. Configurationally broadened X-ray scattering patterns measured at room temperature for dilute toluene solutions of the porphyrin array were compared to scattering patterns calculated from structural ensembles in constant pressure and temperature molecular dynamics simulations. Thermal fluctuations sampled at picosecond intervals within nanosecond time scale dynamic simulations show large-amplitude motions that include porphyrin ring "tipping" around the porphyrin linkage axes and extended hexameric porphyrin array "breathing" motions involving torsional distortions collectively distributed along porphyrin and diphenylethyne groups. Each type of group motion produced characteristic, angle-dependent dampening of scattering features that are needed to reproduce dampening features in the experimental X-ray scattering. However, mismatches in the magnitudes of experimental and simulated dampening of high-angle X-ray scattering patterns show that large-amplitude hexamer array breathing-type motions are significantly under-represented in the simulated ensembles. This comparison between experiment and simulation provides a means not only to interpret scattering data in terms of an explicit atomic model but more generally demonstrates the use of solution X-ray scattering as an experimental benchmark for the development of simulation methods that more accurately predict configurational dynamics of supramolecular assemblies.