Institute for Eye Research

Sydney, Australia

Institute for Eye Research

Sydney, Australia
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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.

Chen X.,Sun Yat Sen University | Chen X.,Vision Cooperative Research Center | Sankaridurg P.,Institute for Eye Research | Sankaridurg P.,Vision Cooperative Research Center | And 8 more authors.
Vision Research | Year: 2010

Interest in peripheral refractive errors has increased as it was hypothesized that peripheral hypermetropia might provide a stimulus for axial elongation (Smith et al., 2005), this study was to determine relative peripheral refractive errors (RPRE) of the eyes of a group of Chinese children and adults. Central and peripheral (20°, 30°, 40° at nasal, temporal, superior and inferior meridians of retina) refractive errors were obtained from cyclopleged eyes of 40 children and 42 adults with a Shin-Nippon auto-refractor. Only right eyes were considered. Central spherical equivalent (M) was used to classify the eyes as Moderate Myopia (MM, -3.00 < M ≤ -6.00 D), Low Myopia (LM, -0.50 ≤ M ≤ -3.00 D), Emmetropia (E, -0.50 < M < +0.50 D) and Low Hypermetropia (LH, +0.50 < M ≤ +2.00 D). RPRE was calculated as the difference in M between the central and peripheral positions. The results showed that in both children and adults, horizontally, the RPRE profile for the MM group had a relative hypermetropic shift and in contrast, the profile for LH demonstrated a relative myopic shift. The difference in the profile between the MM and LH group was significant (p < 0.05). Also, the RPRE profile for MM group was different between adults and children with adult eyes showing greater amount of hypermetropic shift. Vertically, the RPRE profile of all the refractive error groups showed a myopic shift. Off-axis astigmatism increased and horizontally a shift from 'with the rule' to 'against the rule' astigmatism was observed for all groups. Our observations demonstrated that in Chinese eyes, the myopic group present a hyperopic shift in the periphery, the hypermetropic eye present a myopic shift and the emmetropic eyes present no differences to the fovea, which are similar to those reports in Caucasian eyes. The variations in the RPRE between various refractive error groups can be explained on the basis of eye shape. © 2009 Elsevier Ltd. All rights reserved.

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.

Wu Y.,Institute for Eye Research | Wu Y.,University of New South Wales | Carnt N.,Institute for Eye Research | Carnt N.,University of New South Wales | And 4 more authors.
Eye and Contact Lens | Year: 2010

Purpose: To identify and compare the current contact lens and lens storage case hygiene recommendations amongst three different advisory sources: manufacturers of contact lens disinfecting solutions, the Food and Drug Administration of USA, and optometrists prescribing contact lenses in New South Wales, Australia. Methods: A literature review of contact lens and lens case cleaning instructions from the product inserts of five multipurpose disinfecting solutions (AOSept/ClearCare, Aquify, Complete, Opti-free Replenish, and Renu) and the Food and Drug Administration official Web site. In addition, 77 optometrists were surveyed with self-administered questionnaires, which gathered information about hygiene behaviors recommended for lens wearers in routine consultations. The recommendations were tabulated into two tables specific to contact lens and lens case cleaning instructions. Results: Lens case cleaning instructions were inconsistent, and limited recommendations were available about drying positions, rinsing, and rubbing of lens cases. In comparison, contact lens cleaning instructions were more comprehensive and included lens cleaning time and rubbing motion. However, confusion remained in some of the cleaning instructions, for rinsing and rubbing lenses in particular. Conclusions: Inconsistent and inadequate contact lens and lens case hygiene recommendations remain prevalent amongst various advisory bodies (industry, regulatory authority, and optometrists). Future research is needed to establish evidence-based contact lens hygiene guidelines. © 2010 Lippincott Williams & Wilkins.

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.

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.

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.

Wu Y.T.,Institute for Eye Research | Wu Y.T.,University of New South Wales | Zhu H.,Institute for Eye Research | Zhu H.,University of New South Wales | And 6 more authors.
Optometry and Vision Science | Year: 2010

Purpose. To evaluate the frequency level and profile of contact lens storage case contamination in asymptomatic contact lens wearers and to examine whether different areas of the same lens case may show a different rate and profile of contamination. The relationship between lens storage case contamination and the age of the lens storage case was also examined. Methods. Sixty-four lens cases and case age information were collected from asymptomatic contact lens wearers. Lens cases were sampled at two locations, the upper rim and the lower base. The samples underwent microbiological investigation for recovery of bacteria and fungi. Contamination rate between the two sampling locations and the relationship between the contamination levels and the age of the lens case were analyzed. Results. Contamination occurred in 58% (37 of 64) of lens cases. The most frequently recovered microorganisms were coagulase-negative Staphylococci (51%, 19 of 37), Bacillus spp. (43%,16 of 37), and fungi (27%,10 of 37). For flat-well lens cases, higher numbers of microorganisms were recovered from the upper rim than that from the lower base (p = 0.02), and a greater variety of Gram-negative bacteria were recovered from the upper rim. A higher recovery rate of Micrococcus spp. (p = 0.02; in flat cases) and coagulase-negative Staphylococci (p = 0.01; for both flat and basket type cases) was found from the base of the case well compared with the upper rim. For stand-up cases, higher numbers of microorganisms were recovered from the lens basket compared to the upper hinge (p = 0.047). Lens cases that were <9 months of age had lower levels of contamination (p = 0.013) than older cases. Conclusions. Frequent replacement of lens cases may reduce microbial contamination. Future studies should specify the areas swabbed in the lens case. Better lens storage case design and additional hygiene attention need to be introduced to reduce contamination in these "risky" areas. Copyright © 2010 American Academy of Optometry.

Wu Y.,Institute for Eye Research | Wu Y.,University of New South Wales | Carnt N.,Institute for Eye Research | Carnt N.,University of New South Wales | And 2 more authors.
Contact Lens and Anterior Eye | Year: 2010

Purpose: To identify the demographics profile of lens wearers, and to evaluate the scope and level of noncompliant, behaviours in lens wearers. Methods: 210 contact lens wearers who attended an optometry clinic at an education and research institute, were surveyed using a self-administered questionnaire. The questionnaire was constructed to gather information regarding contact lens wearer demographics, contact lens hygiene behaviours and, attitudes toward lens care. Multivariate testing between lens wearers' demographic, hygiene, behaviours and attitude to aftercare visit were analysed. Results: One hundred and eleven (62%) of participants responded, with a mean age of 33.8 ± 12 years. 55% of the respondents were female. Major non-compliance aspects identified were poor hand hygiene (11%), inadequate cleaning of lenses (13%) and lens storage cases (61%), and wearers not remembering how often they were advised to return for an aftercare (50%). Lens wearers who purchased contact lenses, from the internet were 3.8 times more likely to forget their aftercare schedule than those who purchased contact lenses from the optometrists (95% CI=1.2-12.2, p=0.024). Conclusion: Poor hand hygiene, inadequate lens care, and not remembering when to come back for aftercares are the common non-compliant behaviours in lens wearers. Purchase of lenses via the internet was associated with lack of awareness of aftercare visit. © 2010 British Contact Lens Association.

Zhao Z.,Institute for Eye Research | Zhao Z.,University of New South Wales | Naduvilath T.,Institute for Eye Research | Flanagan J.L.,Institute for Eye Research | And 7 more authors.
Optometry and Vision Science | Year: 2010

Purpose.: To correlate clinical responses during contact lens wear with the amount of protein or cholesterol extracted from lenses after wear. Methods.: Clinical parameters, including adverse response rates and corneal staining, and symptomatology rating during lens wear were collected from a series of clinical tests comprising four different silicone hydrogel lenses with four different multipurpose solutions. To test for correlates, the amount of total protein or cholesterol extracted from lenses after daily wear were compared statistically to clinical parameters. Results.: The amount of protein (p = 0.008) or cholesterol (p = 0.01) extracted from lenses was higher for those subjects who showed solution-induced corneal staining. Amount of protein extracted was correlated (p < 0.01) with conjunctival staining (R = -0.23), lens front surface wetting (r = 0.14), and lens fit tightness (R = -0.20). These clinical parameters accounted for 48% of lens protein deposition. The amount of cholesterol extracted from lenses was much more weakly associated with clinical variables. Amount of protein or cholesterol extracted from lenses was not associated with the production of any corneal infiltrative or mechanical adverse event during wear and was only very weakly correlated with insertion comfort of lenses. Conclusions.: These results suggest that there may be no physiologically relevant consequence of cholesterol depositing on silicone hydrogel lenses. The amount of protein that deposits onto silicone hydrogel lenses during wear may have more affect on lens performance on-eye. However, the correlations were generally small and may still not indicate any causative relevant physiological response. Further work is required to determine whether there is any direct causative effect to support these correlative findings. Copyright © 2010 American Academy of Optometry.

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