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Posterior Capsule (posterior + capsule)
Selected AbstractsKinematics of the knee at high flexion angles: An in vitro investigationJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2004Guoan Li Abstract Restoration of knee function after total knee, meniscus, or cruciate ligament surgery requires an understanding of knee behavior throughout the entire range of knee motion. However, little data are available regarding knee kinematics and kinetics at flexion angles greater than 120° (high flexion). In this study, 13° cadaveric human knee specimens were tested using an in vitro robotic experimental setup. Tibial anteroposterior translation and internal,external rotation were measured along the passive path and under simulated muscle loading from full extension to 150° of flexion. Anterior tibial translation was observed in the unloaded passive path throughout, with a peak of 31.2 ± 13.2 mm at 150°. Internal tibial rotation increased with flexion to 150° on the passive path to a maximum of 11.1 ± 6.7°. The simulated muscle loads affected tibial translation and rotation between full extension and 120° of knee flexion. Interestingly, at high flexion, the application of muscle loads had little effect on tibial translation and rotation when compared to values at 120°. The kinematic behavior of the knee at 150° was markedly different from that measured at other flexion angles. Muscle loads appear to play a minimal role in influencing tibial translation and rotation at maximal flexion. The results imply that the knee is highly constrained at high flexion, which could be due in part to compression of the posterior soft tissues (posterior capsule, menisci, muscle, fat, and skin) between the tibia and the femur. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] 2267: Safety of the anterior vitreous detachment induced by microplasmin, pharmacologic vitreolysis to separate the posterior capsule from the anterior hyaloidACTA OPHTHALMOLOGICA, Issue 2010J VAN LOOVEREN Purpose The aim of this project is to establish the safety of the use of microplasmin in the vitreolenticular interface to promote the separation of the anterior hyaloid from the posterior capsule. Methods The safety of the use of microplasmin solution will be examined in 24 eyes of 12 rabbits after having performed a cataract surgery and a primary posterior continuous curvilinear capsulorhexis and having exposed the anterior hyaloid interface with a solution of different doses of microplasmin (125µg or 250µg in 0.1ml balanced salt solution)and having left this solution in place during different time intervals starting from 5 minutes to one hour. The rabbit eyes will be examined at well-defined time intervals: day 1 and 7, month 1,2,3,6 and 12. Slitlamp examination and OCT-SLO imaging will be performed to monitor ocular inflammation, visual axis reproliferation and anterior vitreous anatomy. Conclusion Congenital cataracts, whether or not combined with persistent fetal vasculature may present different degrees of congenital dysgenesis of the vitreolenticular interface. Pharmacological separation of the interface between posterior lens capsule and anterior hyaloid would be benificial to improve the surgical outcome. Therefore the feasibility, safety and clinical application of intravitreal injection of microplasmin for this indication need to be examined first. [source] 4241: Optical characterization of PCOACTA OPHTHALMOLOGICA, Issue 2010TJTP VAN DEN BERG Purpose Opacification of the posterior capsule (PCO) is known to degrade visual function on both counts: small angle resolution (visual acuity and contrast sensitivity) as well as large angle light scatter (straylight). No studies have been performed to delineate the optical characteristics of PCO as a basis for explanation of these visual function defects. Methods Preparations of IOL-capsule combinations were harvested from donor eyes after removal of the cornea. They were mounted submersed in saline in an optical set-up, used earlier to characterize the optics of the crystalline lens (van den Berg et al. VR 1999). Illuminated by monochromatic beams of light, the light spreading originating from different areas of the preparation was measured as function of wavelength for different angles. Based on physical optics theory, the optical characteristics of PCO was derived. The data will be presented translated into the straylight parameter, directly comparable to the figures obtained in vivo using the clinical straylight meter (C-Quant from Oculus). Results Twenty successful preparations were harvested with at least some PCO areas. PCO grades varied from severe to slight. Two physically different types of light spreading could be discriminated. One type corresponding to pearl-like appearance, characterized by little wavelenght dependence and smal angle dominance. The other type corresponding to diffuse scatter, characterized by strong wavelength dependence and large angle dominance. The scatter values measured corresponded to clinical measures of straylight in PCO patients using the C-Quant. Conclusion The light scattering characteristics of PCO show two types of optical disturbance: a refractile type, probably dominated by pearl-like structures, and a diffuse type of scattering of yet unclear origin. [source] 4245: Non-surgical strategies for PCO preventionACTA OPHTHALMOLOGICA, Issue 2010IM WORMSTONE Purpose Surgical approaches and IOL design have gone some way to reduce the rate of PCO progression. Despite these efforts PCO remains a common and important problem which diminishes the visual quality of patients and is a major financial burden on healthcare providers. If we are to effectively respond to the problem of PCO then a biological solution has to be adopted to reduce/prevent formation of light scattering changes. Methods Methods have been employed to investigate PCO development, which include in vitro cell culture and capsular bag models; in vivo animal models and post-mortem analysis. These have greatly aided our understanding of PCO. Results A number of basic approaches have been identified to prevent PCO. 1) To kill the entire lens epithelial population. This will require a pharmacological agent, therefore delivery of this drug needs to be localised to the target cells, but have limited access to non-target cells; closed capsular bag systems such as perfect capsule provides opportunity to achieve this aim. 2) Maintenance of a cell monolayer on the posterior capsule. In particular the role of TGF, has been investigated, which is known to cause matrix deformation. Disruption of TGF, signalling pathways can suppress matrix deformation and thus reduce light scatter. 3) Recreation of a lens is the ultimate solution. While it has been shown that lens fibre differentiation can be promoted in animal systems, perfect formation of the lens is not achieved and the protein density is typically low relative to the native lens. Conclusion Strategies to prevent PCO are being actively developed, which will are greatly aided by improved drug delivery systems. The development of biological/pharmacological approaches in concert with improved surgical methods and IOL designs should yield benefit to patients. Commercial interest [source] Bilateral spontaneous rupture of posterior capsule in posterior polar cataractCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 8 2008Hossein Ashraf MD No abstract is available for this article. [source] Operated and unoperated cataract in AustraliaCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 2 2000Catherine A McCarty PhD MPH ABSTRACT Purpose: To quantify the prevalence of cataract, the outcomes of cataract surgery and the factors related to unoperated cataract in Australia. Methods: Participants were recruited from the Visual Impairment Project: a cluster, stratified sample of more than 5000 Victorians aged 40 years and over. At examination sites interviews, clinical examinations and lens photography were performed. Cataract was defined in participants who had: had previous cataract surgery, cortical cataract greater than 4/16, nuclear greater than Wilmer standard 2, or posterior subcapsular greater than 1 mm 2. Results: The participant group comprised 3271 Melbourne residents, 403 Melbourne nursing home residents and 1473 rural residents. The weighted rate of any cataract in Victoria was 21.5%. The overall weighted rate of prior cataract surgery was 3.79%. Two hundred and forty-nine eyes had had prior cataract surgery. Of these 249 procedures, 49 (20%) were aphakic, 6 (2.4%) had anterior chamber intraocular lenses and 194 (78%) had posterior chamber intraocular lenses. Two hundred and eleven of these operated eyes (85%) had best-corrected visual acuity of 6/12 or better, the legal requirement for a driver's license. Twenty-seven (11%) had visual acuity of less than 6/18 (moderate vision impairment). Complications of cataract surgery caused reduced vision in four of the 27 eyes (15%), or 1.9% of operated eyes. Three of these four eyes had undergone intracapsular cataract extraction and the fourth eye had an opaque posterior capsule. No one had bilateral vision impairment as a result of cataract surgery. Surprisingly, no particular demographic factors (such as age, gender, rural residence, occupation, employment status, health insurance status, ethnicity) were related to the presence of unoperated cataract. Conclusions: Although the overall prevalence of cataract is quite high, no particular subgroup is systematically under-serviced in terms of cataract surgery. Overall, the results of cataract surgery are very good, with the majority of eyes achieving driving vision following cataract extraction. [source] | ||||||||||