Vision Cooperative Research Center

Sydney, Australia

Vision Cooperative Research Center

Sydney, Australia
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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.

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.

Smith III. E.L.,University of Houston | Smith III. E.L.,Vision Cooperative Research Center | Hung L.-F.,University of Houston | Hung L.-F.,Vision Cooperative Research Center | And 2 more authors.
Investigative Ophthalmology and Visual Science | Year: 2012

PURPOSE. Time spent outdoors reduces the likelihood that children will develop myopia, possibly because light levels are much higher outdoors than indoors. To test this hypothesis, the effects of high ambient lighting on vision-induced myopia in monkeys were determined. METHODS. Monocular form deprivation was imposed on eight infant rhesus monkeys. Throughout the rearing period (23 ± 2 to 132 ± 8 days), auxiliary lighting increased the cage-level illuminance from normal lighting levels (15-630 lux) to ~25,000 lux for 6 hours during the middle of the daily 12-hour light cycle. Refractive development and axial dimensions were assessed by retinoscopy and ultrasonography, respectively. Comparison data were obtained in previous studies from 18 monocularly form-deprived and 32 normal monkeys reared under ordinary laboratory lighting. RESULTS. Form deprivation produced axial myopia in 16 of 18 normal-light-reared monkeys. In contrast, only 2 of the 8 highlight- reared monkeys developed myopic anisometropias, and in 6 of these monkeys, the form-deprived eyes were more hyperopic than their fellow eyes. The treated eyes of the high-light-reared monkeys were more hyperopic than the form-deprived eyes of the normal-light-reared monkeys. In addition, both eyes of the high-light-reared monkeys were more hyperopic than those of normal monkeys. CONCLUSIONS. High ambient lighting retards the development of form-deprivation myopia in monkeys. These results are in agreement with the hypothesis that the protective effects of outdoor activities against myopia in children are due to exposure to the higher light levels encountered outdoors. It is possible that therapeutic protection against myopia can be achieved by manipulating indoor lighting levels. © 2012 The Association for Research in Vision and Ophthalmology, Inc.

Smith III E.L.,University of Houston | Hung L.-F.,University of Houston | Hung L.-F.,Vision Cooperative Research Center | Arumugam B.,University of Houston | And 3 more authors.
Investigative Ophthalmology and Visual Science | Year: 2013

PURPOSE. To determine whether high light levels, which have a protective effect against formdeprivation myopia, also retard the development of lens-induced myopia in primates. METHODS. Hyperopic defocus was imposed on 27 monkeys by securing -3 diopter (D) lenses in front of one eye. The lens-rearing procedures were initiated at 24 days of age and continued for periods ranging from 50 to 123 days. Fifteen of the treated monkeys were exposed to normal laboratory light levels (~350 lux). For the other 12 lens-reared monkeys, auxiliary lighting increased the illuminance to 25,000 lux for 6 hours during the middle of the daily 12 hour light cycle. Refractive development, corneal power, and axial dimensions were assessed by retinoscopy, keratometry, and ultrasonography, respectively. Data were also obtained from 37 control monkeys, four of which were exposed to high ambient lighting. RESULTS. In normal- and high-light-reared monkeys, hyperopic defocus accelerated vitreous chamber elongation and produced myopic shifts in refractive error. The high light regimen did not alter the degree of myopia (high light: -1.69 6 0.84 D versus normal light: ±2.08 6 1.12 D; P 1/4 0.40) or the rate at which the treated eyes compensated for the imposed defocus. Following lens removal, the high light monkeys recovered from the induced myopia. The recovery process was not affected by the high lighting regimen. CONCLUSIONS. In contrast to the protective effects that high ambient lighting has against formdeprivation myopia, high artificial lighting did not alter the course of compensation to imposed defocus. These results indicate that the mechanisms responsible for form-deprivation myopia and lens-induced myopia are not identical. © 2013 The Association for Research in Vision and Ophthalmology, Inc.

Smith III E.L.,University of Houston | Smith III E.L.,Vision Cooperative Research Center | Hung L.-F.,University of Houston | Hung L.-F.,Vision Cooperative Research Center | And 2 more authors.
Eye (Basingstoke) | Year: 2014

Investigations employing animal models have demonstrated that ocular growth and refractive development are regulated by visual feedback. In particular, lens compensation experiments in which treatment lenses are used to manipulate the eye's effective refractive state have shown that emmetropization is actively regulated by signals produced by optical defocus. These observations in animals are significant because they indicate that it should be possible to use optical treatment strategies to influence refractive development in children, specifically to slow the rate of myopia progression. This review highlights some of the optical performance properties of the vision-dependent mechanisms that regulate refractive error development, especially those that are likely to influence the efficacy of optical treatment strategies for myopia. In this respect, the results from animal studies have been very consistent across species; however, to facilitate extrapolation to clinical settings, results are presented primarily for nonhuman primates. In agreement with preliminary clinical trials, the experimental data show that imposed myopic defocus can slow ocular growth and that treatment strategies that influence visual signals over a large area of the retina are likely to be most effective. © 2014 Macmillan Publishers Limited. All rights reserved.

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.

Lovicu F.J.,University of Sydney | Lovicu F.J.,Vision Cooperative Research Center | McAvoy J.W.,University of Sydney | McAvoy J.W.,Vision Cooperative Research Center | de Iongh R.U.,University of Melbourne
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2011

Growth factors play key roles in influencing cell fate and behaviour during development. The epithelial cells and fibre cells that arise from the lens vesicle during lens morphogenesis are bathed by aqueous and vitreous, respectively. Vitreous has been shown to generate a high level of fibroblast growth factor (FGF) signalling that is required for secondary lens fibre differentiation. However, studies also show that FGF signalling is not sufficient and roles have been identified for transforming growth factor-β and Wnt/Frizzled families in regulating aspects of fibre differentiation. In the case of the epithelium, key roles for Wnt/β-catenin and Notch signalling have been demonstrated in embryonic development, but it is not known if other factors are required for its formation and maintenance. This review provides an overview of current knowledge about growth factor regulation of differentiation and maintenance of lens cells. It also highlights areas that warrant future study. © 2011 The Royal Society.

Wang Q.,University of Sydney | Mcavoy J.W.,University of Sydney | Mcavoy J.W.,Vision Cooperative Research Center | Lovicu F.J.,University of Sydney | Lovicu F.J.,Vision Cooperative Research Center
Investigative Ophthalmology and Visual Science | Year: 2010

Purpose. Although some of the factors and signaling pathways that are involved in induction of fiber differentiation have been defined, such as FGF-mediated MAPK/ERK and PI3-K/Akt signaling, the factors in the vitreous that regulate this differentiation process in vivo have yet to be identified. The purpose of this study was to better understand the role of growth factors in vitreous that regulate this process by further characterizing the signaling pathways involved in lens fiber differentiation.Methods. Rat lens epithelial explants were used to compare the ability of vitreous, IGF-1, PDGF-A, EGF, and FGF-2 to stimulate the phosphorylation of ERK1/2 and Akt leading to fiber differentiation, in the presence or absence of selective receptor tyrosine kinase (RTK) inhibitors.Results. Similar to vitreous, FGF induced a sustained ERK1/2 signaling profile, unlike IGF, PDGF, and EGF, which induced a more transient (shorter) activation of ERK1/2. For Akt activation, IGF was the only factor that induced a profile similar to vitreous. IGF, PDGF, and EGF potentiated the effects of a low dose of FGF on lens fiber differentiation by extending the duration of ERK1/2 phosphorylation. In the presence of selective RTK inhibitors, although the sustained vitreous-induced ERK1/2 signaling profile and subsequent fiber differentiation was perturbed, the results also showed that, although prolonged ERK1/2 phosphorylation was necessary, it was not sufficient for fiber differentiation to proceed.Conclusions. These results are consistent with FGF's being the key growth factor involved in vitreous-induced signaling leading to lens fiber differentiation; however, they also indicate that other vitreal growth factors such as IGF may be involved in fine-tuning ERK1/2- and Akt-phosphorylation to the level that is necessary for initiation and/or maintenance of lens fiber differentiation in vivo. © Association for Research in Vision and Ophthalmology.

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.

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.

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