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Sydney, Australia

Urs R.,University of Miami | Ho A.,Institute for Eye Research | Ho A.,Vision Cooperative Research Center | Ho A.,University of New South Wales | And 4 more authors.
Vision Research | Year: 2010

Purpose: To develop an age-dependent mathematical model of the zero-order shape of the isolated ex vivo human crystalline lens, using one mathematical function, that can be subsequently used to facilitate the development of other models for specific purposes such as optical modeling and analytical and numerical modeling of the lens. Methods: Profiles of whole isolated human lenses (n=30) aged 20-69, were measured from shadow-photogrammetric images. The profiles were fit to a 10th-order Fourier series consisting of cosine functions in polar-co-ordinate system that included terms for tilt and decentration. The profiles were corrected using these terms and processed in two ways. In the first, each lens was fit to a 10th-order Fourier series to obtain thickness and diameter, while in the second, all lenses were simultaneously fit to a Fourier series equation that explicitly include linear terms for age to develop an age-dependent mathematical model for the whole lens shape. Results: Thickness and diameter obtained from Fourier series fits exhibited high correlation with manual measurements made from shadow-photogrammetric images. The root-mean-squared-error of the age-dependent fit was 205μm. The age-dependent equations provide a reliable lens model for ages 20-60. years. Conclusion: The contour of the whole human crystalline lens can be modeled with a Fourier series. Shape obtained from the age-dependent model described in this paper can be used to facilitate the development of other models for specific purposes such as optical modeling and analytical and numerical modeling of the lens. © 2010 Elsevier Ltd. Source

Stahl U.,Vision Cooperative Research Center | Stahl U.,University of New South Wales | Willcox M.,Vision Cooperative Research Center | Willcox M.,University of New South Wales | And 4 more authors.
Clinical and Experimental Optometry | Year: 2012

The tear film is a nourishing, lubricating and protecting layer that bathes the ocular surface. It is continuously replenished through cycles of production and elimination via evaporation, absorption and drainage. These processes are often referred to as tear film dynamics. Osmolality is an objective clinical measurement that provides insight into the balance of these complex tear film dynamics. Balanced tear production and elimination is vital for tear film integrity, stability and normal osmolality. Imbalances cause alterations of the tear film structure and composition, ultimately leading to tear film instability and measurable tear film hyperosmolality. Elevated tear film osmolality is considered a core mechanism in dry eye, forming the basis of dry eye symptoms and leading to ocular surface damage. Despite its immense potential in the diagnosis of dry eye, tear film osmolality is not commonly assessed. This review will focus on the current knowledge of tear film dynamics and tear film osmolality. © 2011 Vision Co-operative Research Centre. Clinical and Experimental Optometry © 2011 Optometrists Association Australia. Source

Flanagan J.L.,Institute for Eye Research | Simmons P.A.,Allergan, Inc. | Vehige J.,Allergan, Inc. | Willcox M.D.,Institute for Eye Research | And 3 more authors.
Nutrition and Metabolism | Year: 2010

Carnitine is a conditionally essential nutrient that plays a vital role in energy production and fatty acid metabolism. Vegetarians possess a greater bioavailability than meat eaters. Distinct deficiencies arise either from genetic mutation of carnitine transporters or in association with other disorders such as liver or kidney disease. Carnitine deficiency occurs in aberrations of carnitine regulation in disorders such as diabetes, sepsis, cardiomyopathy, malnutrition, cirrhosis, endocrine disorders and with aging. Nutritional supplementation of L-carnitine, the biologically active form of carnitine, is ameliorative for uremic patients, and can improve nerve conduction, neuropathic pain and immune function in diabetes patients while it is life-saving for patients suffering primary carnitine deficiency. Clinical application of carnitine holds much promise in a range of neural disorders such as Alzheimer's disease, hepatic encephalopathy and other painful neuropathies. Topical application in dry eye offers osmoprotection and modulates immune and inflammatory responses. Carnitine has been recognized as a nutritional supplement in cardiovascular disease and there is increasing evidence that carnitine supplementation may be beneficial in treating obesity, improving glucose intolerance and total energy expenditure. © 2010 Flanagan et al. Source

Saville J.T.,University of Wollongong | Zhao Z.,Institute for Eye Research | Zhao Z.,University of New South Wales | Willcox M.D.P.,Institute for Eye Research | And 3 more authors.
Investigative Ophthalmology and Visual Science | Year: 2010

PURPOSE. To examine the deposition of tear phospholipids and cholesterol onto worn contact lenses and the effect of lens material and lens care solution. METHODS. Lipids were extracted from tears and worn contact lenses using 2:1 chloroform: Methanol and the extract washed with aqueous ammonium acetate, before analysis by electrospray ionization tandem mass spectrometry (ESI-MS/MS). RESULTS. Twenty-three molecular lipids from the sphingomyelin (SM) and phosphatidylcholine (PC) classes were detected in tears, with total concentrations of each class determined to be 5 ± 1 pmol/μL (~3.8 μg/mL) and 6 ± 1 pmol/μL (~ 4.6μg/mL), respectively. The profile of individual phospholipids in both of these classes was shown to be similar in contact lens deposits. Deposition of representative polar and nonpolar lipids were shown to be significantly higher on senofilcon A contact lenses, with ~59 ng/lens SM, 195 ng/lens PC, and 9.9 μg/lens cholesterol detected, whereas balafilcon A lens extracts contained ~19 ng/lens SM, 19 ng/lens PC, and 3.9 μg/lens cholesterol. Extracts from lenses disinfected and cleaned with two lens care solutions showed no significant differences in total PC and SM concentrations; however, a greater proportion of PC than SM was observed, compared with that in tears. CONCLUSIONS. Phospholipid deposits extracted from worn contact lenses show a molecular profile similar to that in tears. The concentration of representative polar and nonpolar lipids deposited onto contact lenses is significantly affected by lens composition. There is a differential efficacy in the removal of PC and SM with lens care solutions. © Association for Research in Vision and Ophthalmology. Source

Zhao Z.,Institute for Eye Research | Zhao Z.,University of New South Wales | Liu J.,Institute for Eye Research | Wasinger V.C.,University of New South Wales | And 5 more authors.
Experimental Eye Research | Year: 2010

Proteins are very important components in tears. Their phosphorylation is an important posttranslational modification affecting biological activity. Using proteomic techniques, this study was designed to analyze phosphoproteins found in open eye basal tears from normal human subjects. Proteins in tear samples were separated in 1-dimensional (1D) and 2-dimensional (2D) gels and phosphoproteins were selectively stained with Pro-Q diamond dye before visualization of all proteins using Sypro Ruby. Potential phosphoproteins in 2D gels were identified by liquid chromatography-mass spectrometry (LC-MS/MS) after trypsin digestion and phosphopeptide enrichment using titanium dioxide (TiO2) columns. The tryptic digests of the tear samples were also analyzed to identify phosphoproteins directly by LC-MS/MS after phosphopeptide enrichment. The major phosphoprotein stained by Pro-Q diamond in the gels and identified by LC-MS/MS from the spots was tear lipocalin. Tear lipocalin was separated into 3 different isoforms and one phosphorylation site (serine at position 24) was identified in one of the isoforms. Prolactin-induced protein, nucleobindin-2 and lipophilin C were also stained with Pro-Q diamond although no phosphorylated peptides from these proteins could be found using LC-MS/MS. Direct analysis of the tear tryptic digests by LC-MS/MS identified a further 12 potential phosphoproteins with tear lipocalin predominant. Four phosphorylation sites (position 24 (serine), 32 (serine), 34 (threonine) and 36 (tyrosine)) were identified for tear lipocalin using this method. These results indicate that tear lipocalin is the predominant phosphoprotein in normal human basal tears. Nucleobindin-2, prolactin-induced protein and lipophilin C also appear to be phosphorylated in basal tear samples. © 2009 Elsevier Ltd. Source

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