Dizziness, but not falls rate, improves after routine cataract surgery: the role of refractive and spectacle changes

YesPurpose To determine whether dizziness and falls rates change due to routine cataract surgery and to determine the influence of spectacle type and refractive factors. Methods Self-reported dizziness and falls were determined in 287 patients (mean age of 76.5 ± 6.3 years, 55% females) before and after routine cataract surgery for the first (81, 28%), second (109, 38%) and both eyes (97, 34%). Dizziness was determined using the short-form of the Dizziness Handicap Inventory. Six-month falls rates were determined using self-reported retrospective data. Results The number of patients with dizziness reduced significantly after cataract surgery (52% vs 38%; χ2 = 19.14, p < 0.001), but the reduction in the number of patients who fell in the 6-months post surgery was not significant (23% vs 20%; χ2 = 0.87, p = 0.35). Dizziness improved after first eye surgery (49% vs 33%, p = 0.01) and surgery on both eyes (58% vs 35%, p < 0.001), but not after second eye surgery (52% vs 45%, p = 0.68). Multivariate logistic regression analyses found significant links between post-operative falls and change in spectacle type (increased risk if switched into multifocal spectacles). Post-operative dizziness was associated with changes in best eye visual acuity and changes in oblique astigmatic correction. Conclusions Dizziness is significantly reduced by first (or both) eye cataract surgery and this is linked with improvements in best eye visual acuity, although changes in oblique astigmatic correction increased dizziness. The lack of improvement in falls rate may be associated with switching into multifocal spectacle wear after surgery.This work was supported by The Dunhill Medical Trust(grant number SA14/0711)

The effect of mesoporous silica impregnation on tribo-electrification characteristics of flurbiprofen

Tribo-electrification is a common occurrence within the pharmaceutical industry where solid dosage forms constitute majority of pharmaceutical formulations. Tribo-electrification of powders leads to a range of complications such as adhesion of particulate material to the processing equipment resulting in segregation, affecting the content uniformity. Flurbiprofen, a highly charging material, was used as a model drug to investigate the tribo-electrification and adhesion characteristics by impregnating the model drug inside a mesoporous silica matrix. The model drug was impregnated using i) solvent loading, and ii) physical mixing methods, at varying degree of silica to drug ratio (5-20% w/w). The resulting mixtures were tribo-charged using a custom built device based on a shaking concept inside a stainless steel capsule, consisting of a Faraday cup and connected to electrometer. The electrostatic charge and the percentage adhesion of Flurbiprofen were reduced in both drug loading methods. The solvent impregnation method using acetone was more successful at reducing the electrostatic charge build up on flurbiprofen than physical powder mixing. The percentage adhesion to the shaking capsule was reduced notably as a result of loading the drug in the SBA-15 porous network. The results illustrate that the incorporation of highly charged model drug inside a low-charging pharmaceutical carrier system to be an effective approach in control the induction of tribo-electrification phenomena during powder processing

Powder Compaction: Compression Properties of Cellulose Ethers

Effective development of matrix tablets requires a comprehensive understanding of different raw material attributes and their impact on process parameters. Cellulose ethers (CE) are the most commonly used pharmaceutical excipients in the fabrication of hydrophilic matrices. The innate good compression and binding properties of CE enable matrices to be prepared using economical direct compression (DC) techniques. However, DC is sensitive to raw material attributes, thus, impacting the compaction process. This article critically reviews prior knowledge on the mechanism of powder compaction and the compression properties of cellulose ethers, giving timely insight into new developments in this field

Optical characteristics of Alvarez variable-power spectacles

Purpose: To establish the optical performance of currently-available Alvarez variable-power spectacles in relation to their possible utility for ametropes and presbyopes.Methods: Two commercial designs of variable-power (variable-focus) spectacles were studied: FocusSpecs and Adlens Adjustables. Using focimetry, power and prism at three different power settings were measured across the aperture of the lenses of each design and local optical quality was explored in more detail using interferometry.Results: In general, equivalent-sphere powers at all lens settings were adequately stable across the central aperture (about 20 mm diameter) of the lenses, with prism changes following the Prentice rule. Some astigmatism (generally ≤0.5 DC over the central area) and higher-order aberration (comparable to the normal wavefront aberration of the eye) were found, the latter increasing towards the edge of the useable lens area.Conclusions: Within their designed power ranges, optical performance of currently-available Alvarez variable-power spectacles appears to be adequate to correct the distance and near vision of spherical ametropes

Development and validation of the vision-related dizziness questionnaire

YesPurpose: To develop and validate the first patient-reported outcome measure (PROM) to quantify vision-related dizziness. Dizziness is a common, multifactorial syndrome that causes reductions in quality of life and is a major risk factor for falls, but the role of vision is not well understood. Methods: Potential domains and items were identified by literature review and discussions with experts and patients to form a pilot PROM, which was completed by 335 patients with dizziness. Rasch analysis was used to determine the items with good psychometric properties to include in a final PROM, to check undimensionality, differential item functioning, and to convert ordinal questionnaire data into continuous interval data. Validation of the final 25-item instrument was determined by its convergent validity, patient, and item-separation reliability and unidimensionality using data from 223 patients plus test–retest repeatability from 79 patients. results: 120 items were originally identified, then subsequently reduced to 46 to form a pilot PROM. Rasch analysis was used to reduce the number of items to 25 to produce the vision-related dizziness or VRD-25. Two subscales of VRD-12-frequency and VRD-13-severity were shown to be unidimensional, with good psychometric properties. Convergent validity was shown by moderately good correlations with the Dizziness Handicap Inventory (r = 0.75) and good test–retest repeatability with intra-class correlation coefficients of 0.88. conclusion: VRD-25 is the only PROM developed to date to assess vision-related dizziness. It has been developed using Rasch analysis and provides a PROM for this under-researched area and for clinical trials of interventions to reduce vision-related dizziness.College of Optometrists (UK) research studentship

Urea Finishing Process: Prilling versus Granulation

Solid urea is the largest nitrogen fertilizer product which is produced in two forms of granules and prills. Although the chemical properties of both prills and granules remain similar, their different physical and mechanical properties are distinguishable and make them suitable for different application either as fertilizer or raw materials for chemical industry. The objective of this work is to analyses physical and mechanical properties of urea granules produced in two different plants in Malaysia using fluidized bed process and compare them with the imported urea prills to the country; hence make a process-product relationship for urea finishing processes. Results of size distribution of the samples show that the most of the granules fall in the size range between 2.40 and 3.50 mm, whereas the prills size is around 1.60 mm. Strength measurement using side crushing test also shows that the prills with the average failure load of 3.80 N remain significantly weaker than the granules with failure load of 10-17 N. Strength distribution of the particles also shows that a more uniform strength distribution is observed for the prills than the granules. It is concluded that the urea prilling process is the finishing process which produces the weaker and the more uniform size and strength of the particles than the fluidized-bed granulation process

Dizziness and falls rate changes after routine cataract surgery and the influence of visual and refractive factors

Purpose: To determine whether symptoms of dizziness and fall rates change due to routine cataract surgery and to determine the influence of visual and refractive factors on these common problems in older adults. Methods: Self-reported dizziness and falls were determined in 287 subjects (mean age of 76.5±6.3 years, 55% females) before and after routine cataract surgery for the first (81, 28%), second (109, 38%) and both eyes (97, 34%). Six-month falls rates were determined using self-reported retrospective data. Dizziness was determined using the short-form of the Dizziness Handicap Inventory. Results: The number of patients with dizziness reduced significantly after cataract surgery (52% vs. 38%; χ2 = 19.14 , p<0.001), but the reduction in number of patients who fell in the 6-months post surgery was not significant (23% vs. 20%; χ2= 0.87, p=0.35). Multivariate logistic regression analyses found significant links between post-operative falls and change in spectacle type (increased risk if switched into multifocal spectacles). Post-operative dizziness was associated with changes in best eye visual acuity and changes in oblique astigmatic correction. Conclusions: Dizziness is significantly reduced by cataract surgery and this is linked with improvements in best eye visual acuity, although changes in oblique astigmatic correction increased dizziness. The lack of improvement in falls rate may be associated with switching into multifocal spectacle wear after surgery.The Dunhill Medical Trus