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Ale J.B.,Vision Cooperative Research Center
Nepalese journal of ophthalmology : a biannual peer-reviewed academic journal of the Nepal Ophthalmic Society : NEPJOPH | Year: 2011

To review published studies reporting the posterior chamber intraocular lens tilt and decentration after surgically uneventful implantation. Potential influences of normally occurring misalignment of modern designs of IOL on the optical performances are discussed. Published theoretical and clinical studies in relation to primarily implanted posterior chamber intraocular lenses and reports relating to more recent development of intraocular lens technologies were reviewed. Capsulotomy type and integrity, ocular pathology, fixation position of the haptics are some of the important factors causing the misalignment. On an average, a 2-3 degrees tilt and a 0.2 -0.3 mm decentration are common, and which remain clinically unnoticed for any design of IOL. However, theoretical studies predict deterioration of retinal image quality particularly with customized wavefront correcting IOLs. More than a 10 degrees tilt and above 1 mm decentration are occasionally reported even with modern cataract surgery in about 10 % of pseudophakic population. The rate and extent of the complication have lowered substantially concomitant with developments in surgical techniques and IOL designs. While emerging designs of modern IOLs offer improved quality of postoperative vision, optimum performance is vastly influenced by the position of the device in the eye. Therefore, additional precision in alignment of modern designs of IOL may be warranted. © NEPjOPH. Source


Smith E.L.,University of Houston | Smith E.L.,Vision Cooperative Research Center
Optometry and Vision Science | Year: 2011

It is well established that refractive development is regulated by visual feedback. However, most optical treatment strategies designed to reduce myopia progression have not produced the desired results, primarily because some of our assumptions concerning the operating characteristics of the vision-dependent mechanisms that regulate refractive development have been incorrect. In particular, because of the prominence of central vision in primates, it has generally been assumed that signals from the fovea determine the effects of vision on refractive development. However, experiments in laboratory animals demonstrate that ocular growth and emmetropization are mediated by local retinal mechanisms and that foveal vision is not essential for many vision-dependent aspects of refractive development. However, the peripheral retina, in isolation, can effectively regulate emmetropization and mediate many of the effects of vision on the eye's refractive status. Moreover, when there are conflicting visual signals between the fovea and the periphery, peripheral vision can dominate refractive development. The overall pattern of results suggests that optical treatment strategies for myopia that take into account the effects of peripheral vision are likely to be more successful than strategies that effectively manipulate only central vision. Copyright © 2011 American Academy of Optometry. Source


Aller T.A.,Private Practice | Aller T.A.,Vision Cooperative Research Center
Eye (Basingstoke) | Year: 2014

Myopia has been increasing in prevalence throughout the world, reaching over 90% in some East Asian populations. There is increasing evidence that whereas genetics clearly have an important role, the type of visual environment to which one is exposed to likely influences the onset, progression, and cessation of myopia. Consequently, attempts to either modify the environment or to reduce the exposure of the eye to various environmental stimuli to eye growth through the use of various optical devices are well under way at research centers around the globe. The most promising of current treatments include low-percentage atropine, bifocal soft contact lenses, orthokeratology, and multifocal spectacles. These methods are discussed briefly and are then categorized in terms of their expected degree of myopia progression control. A clinical strategy is presented for selecting the most effective treatment for the appropriate type of patient at the optimal stage of refractive development to achieve the maximum control of myopia progression. © 2014 Macmillan Publishers Limited. All rights reserved. Source


Smith E.L.,University of Houston | Smith E.L.,Vision Cooperative Research Center
Experimental Eye Research | Year: 2013

In order to develop effective optical treatment strategies for myopia, it is important to understand how visual experience influences refractive development. Beginning with the discovery of the phenomenon of form deprivation myopia, research involving many animal species has demonstrated that refractive development is regulated by visual feedback. In particular, animal studies have shown that optically imposed myopic defocus slows axial elongation, that the effects of vision are dominated by local retinal mechanisms, and that peripheral vision can dominate central refractive development. In this review, the results obtained from clinical trials of traditional optical treatment strategies employed in efforts to slow myopia progression in children are interpreted in light of the results from animal studies and are compared to the emerging results from preliminary clinical studies of optical treatment strategies that manipulate the effective focus of the peripheral retina. Overall, the results suggest that imposed myopic defocus can slow myopia progression in children and that the effectiveness of an optical treatment strategy in reducing myopia progression is influenced by the extent of the visual field that is manipulated. © 2012 Elsevier Ltd. Source


Masoudi S.,Vision Cooperative Research Center | Masoudi S.,Brien Holden Vision Institute | Zhong L.,University of New South Wales | Raftery M.J.,University of New South Wales | And 3 more authors.
Investigative Ophthalmology and Visual Science | Year: 2014

Purpose. To establish the use of selected reaction monitoring (SRM) mass spectrometry for quantification of tear proteins. Methods. Tear samples were collected on multiple occasions (7-10 days) from healthy subjects with contact lens wear (CL = 3) and without contact lens wear (NCL = 4). Tear proteins were denatured using 8M urea, reduced with iodoacetamide, precipitated by acetone, and digested using trypsin. Internal standards were included by adding isotopically-labelled standards of known concentrations to the samples. Lactoferrin, lysozyme, prolactin-induced protein, lipocalin 1, and proline-rich protein 4 were quantified using liquid chromatography-triple quadruple mass spectrometry in conjunction with selected reaction monitoring. Results. The limits of quantification for the selected peptides were below 50 pg/μL. The recovery of peptides from spiked digested tears was greater than or equal to 56% and the coefficient of variation values were less than or equal to 16%. The concentration of lactoferrin (1.20 ± 0.77 μg/μL), lysozyme (2.11 ± 1.50 μg/μL), and lipocalin-1 (1.75 ± 0.99 μg/μL) were consistent with previous ELISA studies. Tear levels of prolactin-induced protein (0.09 ± 0.06 μg/μL) and proline-rich 4 (0.80 ± 0.50 μg/μL) are reported here for the first time. Conclusions. The SRM method can be used for simultaneous detection and quantification of selected proteins in low volumes of human tear samples (2.5 μL per sample) without prior purification of each protein component or need for antibodies. © 2014 The Association for Research in Vision and Ophthalmology, Inc. Source

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