Contact Lens & Anterior Eye

Editorial Board

2012-06-01

Editorial

Shehzad A. Naroo — 2012-06-01

Readers may have noted that a short but very important announcement was made in the last issue of CLAE, at the top of the contents page. CLAE has been accepted by Thomson Reuters for abstracting and indexing in its SciSearch, Journal Citation Reports, and Current Contents services. This will ensure a greater visibility to the international research community. In addition, in June 2012 CLAE will receive its very first official Impact Factor – a measure of journal influence of importance to authors and readers alike. The impact factor value has not yet been decided but internal estimates by Elsevier estimate it will be around 1, and it will be applied to all CLAE issue back to January 2009 (volume 32). I would guess readers at this stage would have one of two responses – either ‘that's good news’ or perhaps ‘what's an impact factor?’ If you are in the latter camp then allow me to try and explain. Basically the impact factor or citation index of a journal is based on how many times in the previous year papers published in that journal in the previous two years were cited by authors publishing in other journals. So the 2012 impact factor for CLAE is calculated on how many times in 2011 papers that were published in CLAE in 2010 and 2009 were cited in other journals in 2011, divided by the number of papers published in CLAE 2010 and 2009. Essentially authors will try and get their work published in journals with a higher impact factor as it is thought that the paper will be cited more by other authors or the paper will have higher visibility in the arena. For universities having its published output in higher journals is one of the markers used to judge esteem. For individual authors publishing in journals with a higher impact factor or the number of times one of their papers is published is something that they are likely to add to their CVs or demonstrate the importance of their work. Journals with higher impact factors tend to be more review journals or journals with a wider spectrum so for a relatively small journal with a specialised field like CLAE it is great to be listed with a citation index.

Function of lipids – their fate in contact lens wear: An interpretive review

Amandeep Panaser, Brian J. Tighe — 2012-02-10

Abstract: Lipids play a vital role in the body at many interfaces. Examples include the lubrication of articulating joints by synovial fluid, the coating of the lung by pulmonary surfactant and the functions of the tear film in the protection of the anterior eye. The role of the lipids is similar at each site – acting as boundary lubricants and reducing surface and interfacial tension. This review focuses on how and why contact lens wear can disrupt the normal function of lipids within the tear film and explains how the otherwise advantageous presence and function of tear lipids can become disadvantageous, causing problems for the wearer. Because the contact lens is some ten times thicker than the tear film, lipids deposited on the anterior surface become immobilised, reducing lipid turnover and thus leading to prolonged exposure to oxygen and light with consequent generation of degradation products. These degraded lipids reduce lens wettability and have additionally been linked to problems of contact lens discomfort and intolerance. Lipid problems are influenced by the thickness of the lens, the material, surface modification, mode of wear and ultimately the subject. The most influential of these variables is frequently the subject.

Long term effects of the daily wear of senofilcon A silicone hydrogel contact lenses on eyelid tissues

Michel Guillon, Cécile Maïssa — 2012-03-14

Abstract: Purpose: Eyelid changes have been reported with silicone hydrogel contact lenses. It is hypothesized that those changes are associated with the mechanical interaction between the contact lens front surface and eyelid tissues and, are specific to contact lens type rather than a general effect of the lens category. The purpose of this study was to assess the effect of refitting into a silicone hydrogel on a daily wear basis to current contact lens wearers, lapsed wearers and neophytes on eyelid physiology.Methods: The investigation was a 2-year prospective investigation of ACUVUE® OASYS(R) with HYDRACLEAR® Plus (senofilcon A) used with care systems, representative of current practice.Results: 90 subjects were enrolled of whom 64 subjects completed the investigation. The results obtained were as follows:Conclusions: The results of the study demonstrated that senofilcon A, worn on a daily wear basis and replaced every 2 weeks, did not produce any eyelid tissue changes in previous non-contact lens wearers at baseline and revealed no change or a slight improvement of the eyelid tissues of established contact lens wearers.

The influence of lens power and center thickness on the intraocular pressure measured through soft lenses: A comparison of two noncontact tonometers

Kelechi C. Ogbuehi — 2012-02-10

Abstract: Purpose: To quantify the influence of soft contact lens power and thickness on the intraocular pressure (IOP).Methods: Thirty-nine young, healthy adult volunteers completed this study. One eye of each subject was randomly assigned either a +6D or a −6D high water content daily disposable lens. The other eye was fitted with the second lens. Triplicate measurements of IOP were taken before, during, and after contact lens wear. Each time, IOP was assessed in a randomized order with two noncontact tonometers. The lenses were swapped between eyes during a second session of measurements, one week later.Results: In the first session with the +6D lenses, the average IOPs (±SDs) before, with the lenses fitted, and after the lenses were removed, were: 14.3±2.9mmHg, 17.0±3.3mmHg and 13.9±3.1mmHg, respectively, for the CT80 and 13.6±3.1mmHg, 17.1±4.5mmHg and 13.3±2.9mmHg, respectively, for the PT100. The corresponding values for the first session with the −6D lenses were: 14.3±3.1mmHg, 13.1±3.1mmHg and 14.1±3.3mmHg, respectively, for the CT80 and 13.6±3.2mmHg, 13.0±3.0mmHg and 13.6±3.2mmHg, respectively, for the PT100. IOP significantly (P<0.05) increased (+ΔIOP=2.7±0.4mmHg with the CT80 in the first session) with the +6D lenses, but decreased (P<0.05) when the −6D lenses were fitted (−ΔIOP=0.6±0.2mmHg with the PT100 in the first session). The soft contact lens-induced changes were consistent between sessions but varied between tonometers.Conclusions: The measurement of IOP through soft contact lenses resulted in consistent, statistically significant differences in IOP, which were not uniform across tonometers and which did not appear to be solely related to the central thickness of the soft contact lenses.

Corneal changes following short-term rigid contact lens wear

Garima Tyagi, Michael J. Collins, Scott A. Read, Brett A. Davis — 2012-02-24

Abstract: Purpose: The aim of this cross-over study was to investigate the changes in corneal thickness, anterior and posterior corneal topography, corneal refractive power and ocular wavefront aberrations, following the short term use of rigid contact lenses.Method: Fourteen participants wore 4 different types of contact lenses (RGP lenses of 9.5mm and 10.5mm diameter, and for comparison a PMMA lens of 9.5mm diameter and a soft silicone hydrogel lens) on 4 different days for a period of 8h on each day. Measures were collected before and after contact lens wear and additionally on a baseline day.Results: Anterior corneal curvature generally showed a flattening with both of the RGP lenses and a steepening with the PMMA lens. A significant negative correlation was found between the change in corneal swelling and central and peripheral posterior corneal curvature (all p≤0.001). RGP contact lenses caused a significant decrease in corneal refractive power (hyperopic shift) of approximately 0.5D. The PMMA contact lenses caused the greatest corneal swelling in both the central (27.92±15.49μm, p<0.001) and peripheral (17.78±12.11μm, p=0.001) corneal regions, a significant flattening of the posterior cornea and an increase in ocular aberrations (all p≤0.05).Conclusion: The corneal swelling associated with RGP lenses was relatively minor, but there was slight central corneal flattening and a clinically significant hyperopic change in corneal refractive power after the first day of lens wear. The PMMA contact lenses resulted in significant corneal swelling and reduced optical performance of the cornea.

Fibre optics sensors in tear electrolyte analysis: Towards a novel point of care potassium sensor

Daniel Harvey, Neil W. Hayes, Brian Tighe — 2012-03-14

Abstract: The diagnosis of ocular disease is increasingly important in optometric practice and there is a need for cost effective point of care assays to assist in that. Although tears are a potentially valuable source of diagnostic information difficulties associated with sample collection and limited sample size together with sample storage and transport have proved major limitations. Progressive developments in electronics and fibre optics together with innovation in sensing technology mean that the construction of inexpensive point of care fibre optic sensing devices is now possible. Tear electrolytes are an obvious family of target analytes, not least to complement the availability of devices that make the routine measurement of tear osmolarity possible in the clinic. In this paper we describe the design, fabrication and calibration of a fibre-optic based electrolyte sensor for the quantification of potassium in tears using the ex vivo contact lens as the sample source. The technology is generic and the same principles can be used in the development of calcium and magnesium sensors. An important objective of this sensor technology development is to provide information at the point of routine optometric examination, which would provide supportive evidence of tear abnormality.

Long term effects of the daily wear senofilcon A silicone hydrogel contact lens on eyelid tissues

2012-06-01

Long term effects of the daily wear of senofilcon A silicone hydrogel contact lenses on eyelid tissues

2012-06-01