Author: Guillermo Carrillo

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Research Update Issue 11


November 2017  
 
 
 
 

Welcome to our monthly research update
 
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
 
More information on Research Update and how to use it in your contact lens teaching here. Access archived issues via Member Login under Research.
 
 
 
Issue 11 – November 2017
 
Orthokeratology and its effects have been a fascination for many contact lens practitioners. In this issue, we cover the influence of corneal asymmetry and ortho-k lens decentration. The long- term effects of ortho-k remain an area of concern. We include a study that evaluates whether ortho-k causes changes in endothelial morphology in children. Continuing our quest for myopia control, we include an extensive review of contact lenses to slow myopia progression and a report on measuring peripheral defocus in myopia control studies.

A group from Canada attempts to evaluate the change in over-refraction after scleral lens fitting. We also report a study by researchers in Spain who assessed the effect of ageing on ocular surface parameters that would affect multifocal contact lens fitting or IOL implantation. And finally, we include a study that quantifies the discomfort over time of various eyelid cleaners used to manage Demodex.

Enjoy!
The IACLE Education Team
 
 
 
Journals reviewed in this issue  

  JOURNAL VOLUME AND ISSUE NUMBER
 
  Optometry and Vision Science 94:9, 94:11
  Contact Lens & Anterior Eye Articles in Press
  Clinical and Experimental Optometry 100:5 (Special issue: CLs)
  Ophthalmic & Physiological Optics 37:4
  Eye & Contact Lens Published Ahead-of-Print
 
 
 
 
 
 ORTHOKERATOLOGY
 

Ortho-K lens decentration with corneal elevation
To investigate the influence of corneal elevation asymmetry on ortho-k lens decentration, Chen et al fitted 36 eyes of 36 myopic children with four-curve reverse geometry ortho-k lenses. The relationship between angle and magnitude of corneal asymmetry vector and lens decentration was analysed. The mean magnitude of lens decentration was 0.72+0.26mm. The most common decentration was infero-temporal (24, ie 67% of eyes). The magnitude and direction of lens decentration were found to be predetermined by paracentral corneal asymmetry, useful insights in screening for ideal ortho-k candidates.

Optom Vis Sci 2017;94:9 903-907. Click here for abstract

 
 
 
 
 
 ORTHOKERATOLOGY
 

Ortho-K and endothelial morphology of children
To compare changes in endothelial morphology in central and superior cornea over 2 years in children wearing ortho-k and controls wearing single-vision spectacles, Cheung and Cho analyzed endothelial images at two locations in 99 subjects (aged 6-12 years) who had completed myopia control studies. Subjects receiving ortho-k had a smaller reduction in endothelial cell density (ECD) in central cornea compared to controls. Otherwise, there were no significant differences in endothelial morphology changes between the groups. Ortho-k had a minimal effect on the endothelial morphology of children after 2 years of lens wear.

Cont Lens Anterior Eye 2017; DOI: http://dx.doi.org/10.1016/j.clae.2017.10.006. Click here for full text
 
 
 
 
 
 MYOPIA
 

Contact lenses to slow myopia progression
This comprehensive review on contact lenses controlling myopia progression was conducted by Sankaridurg. Soft CLs are one of the more effective modalities, along with ortho-k and atropine. Robust evidence for slowing myopia was found with use of multifocal or multifocal-like CLs, supporting their use to slow the progression of myopia. Further work is needed to determine whether there is rebound on discontinuation and whether there is variation in the magnitude of rebound depending on whether the discontinuation occurs during the sensitive period of ocular growth or after growth has stabilized.

Clin Exp Optom 2017; 100:5 432-437. Click here for full text
 
 
 
 
 
 MYOPIA
 

Contact lens decentration in peripheral gaze
Multifocal CLs slow eye growth, in theory, by creating peripheral myopic defocus but the amount of defocus reported is inconsistent. El-Nimri and Walline conducted this study to determine whether soft mutifocal CL lag could affect peripheral defocus. They measured centration in 40 subjects wearing multifocal CLs in primary gaze. The distance between the CL edge and limbus while looking centrally and 20º in each direction was considered as decentration. CLs lagged up to approximately 0.50mm in various gazes, which could affect measurement of peripheral defocus when subjects turn their eyes instead of their head.

Optom Vis Sci 2017;94:11 1029-1035. Click here for abstract

 
 
 
 
 
 SCLERAL LENSES
 

Change in over-refraction after scleral lens settling
To determine the change in over-refraction, if any, after a scleral lens settled on the eye for 6-8 hours, Bray et al fitted 16 patients of varying refractive errors and average corneal curvatures with trial mini-scleral CLs. While there was no significant change in visual acuity with best sphere over-refraction over a 6-8 hour wearing period, there was a significant change in central corneal clearance. This study confirmed there is no link between reduction in central corneal clearance and change in over-refraction for average corneas.

Ophthalmic Physiol Opt 2017;37:4 467-472. Click here for abstract
 
 
 
 
 
 PHYSIOLOGY
 

Ageing and ocular surface parameters
Rico-del-Viejo et al assessed the effect of ageing on ocular surface parameters affecting multifocal CL fitting. A total 110 subjects were divided into three age groups: <42 years, 42-65 years and >65 years. Symptoms, tear film, slit-lamp findings, lid margin and corneal integrity were assessed. The elderly population presented more ocular surface changes than a young population. A majority of the ocular surface parameters studied presented a fair correlation with age. Women showed more changes due to ageing than men.

Cont Lens Anterior Eye 2017; DOI: http://dx.doi.org/10.1016/j.clae.2017.09.015. Click here for full text
 
 
 
 
 
 EYELIDS
 

Eyelid cleansing products for Demodex
In this prospective, randomized, controlled, crossover, open label study Ngo et al quantified discomfort over time of various eyelid cleansers against Demodex. Five different cleaners were used on 26 participants. They were asked to close their eyes as the product was gently rubbed into the eyelashes and verbally rated their discomfort over the course of 10 min. Three out of five cleansers used in this study induced significant discomfort. These results may help clinicians educate patients about what to expect from eyelid Demodex treatment.

Eye & Contact Lens 2017; DOI: 10.1097/ICL.0000000000000415. Click here for abstract
 
 
 
 
 
For more information on Research Update visit www.iacle.org.
 
 
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Research Update Issue 10


October 2017  
 
 
 
 

Welcome to our monthly research update
 
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
 
More information on Research Update and how to use it in your contact lens teaching here. Access archived issues via Member Login under Research.
 
 
 
Issue 10 – October 2017
 
The influence of lens care products on contact lens comfort has been a topic of discussion recently. This month we look at the effects of multipurpose solutions on hydrogel lens performance. Click on the abstract to find out which solutions were tested. And we join the debate on an important question often asked in practice: ‘What is the appropriate frequency for CL aftercare visits?’

Two studies relate to the interaction between soft CLs and cosmetic products: one on diffusion of eye shadow and another on absorption of cleansing oil. Is there merit in using topical anaesthetic prior to RGP lens fitting? A new study answers this age-old question. We report a study that examines accommodative response of eyes wearing aspheric single-vision contact lenses. And finally, we include a comprehensive review of intracorneal inlays for correcting presbyopia.

Enjoy this month’s update!
The IACLE Education Team
 
 
 
Journals reviewed in this issue  

  JOURNAL VOLUME AND ISSUE NUMBER
 
  Optometry & Vision Science Pre-publication, 94:10
  Clinical & Experimental Optometry 100:5
  Contact Lens & Anterior Eye 40:5, Articles in Press
  Eye & Contact Lens 43:5
 
 
 
 
 
 LENS CARE
 

Multipurpose solutions and hydrogel lens performance
In this prospective, double-masked, randomized, crossover study, Kitamata-Wong et al investigated short-term effects of modern multipurpose solutions (MPS) on CL comfort and dryness, pre-lens tear film stability and ocular surface health, in addition to solution effects on CL surface properties in vitro. Over four visits, subjects were exposed to control solution in one eye and to one of four test solutions in the contralateral eye, for 2h using presoaked lenses. Different MPS showed different effects on the ocular surface. The effect of MPS on CL properties in vitro reflect how the MPS altered pre-lens tear stability.

Optom Vis Sci 2017;DOI: 10.1097/OPX.0000000000001125. Click here for abstract
 
 
 
 
 
 AFTERCARE
 

Rethinking contact lens aftercare frequency
Efron and Morgan conducted this review to rethink CL aftercare in a modern context and explore two overarching issues: the key reasons for conducting aftercare examinations and the appropriate frequency for aftercare visits. Four key clinical reasons for conducting a routine aftercare visit are identified: preserving ocular health, maintaining good vision, optimizing comfort and ensuring satisfactory fitting performance. The authors recommend: first aftercare visit within 1-2 weeks of lens dispensing. Follow-up guidelines are: soft daily disposable, 24 months; soft daily reusable and rigid daily wear, 12 months; soft and rigid extended wear, six months.

Clin Exp Optom 2017;100:5 411-431. Click here for full text
 
 
 
 
 
 POLYMER INTERACTION
 

Diffusion of eye shadow in soft contact lenses
Tavazzi et al quantified and compared absorption of the dye component of a powder eyeshadow into soft CLs of five hydrogel and four silicone hydrogel (SiHy) materials. Diffusivity was higher in SiHys than in hydrogels. In hydrogels, diffusivity was greater in materials with lower oxygen transmissibility. Diffusion of dye was found to follow Fick’s law and is driven by polymer-dye interaction, which governs lens hydration and swelling. Based on results with one specific cosmetic, SiHys were found to be not recommended for prolonged wear for eyeshadow wearers.

Cont Lens Anterior Eye 2017;40:5 335-339. Click here for full text
 
 
 
 
 
 POLYMER INTERACTION
 

Cleansing oil absorption by soft contact lenses
This study by Tsukiyama et al investigated absorption of a cosmetic product by three brands of hydrogel and seven brands of SiHy contact lenses (SHCLs) along with the degree of differences between these dry and wet states. The cleansing oil (for removing make-up) was not absorbed by hydrogel lenses under wet or dry conditions. SHCLs exhibited different degrees of resistance depending on the lens material. Some SHCLs absorbed cosmetic cleansing oil more under dry conditions than under wet conditions

Eye & Contact Lens 2017;43:5 318-323. Click here for full text
 
 
 
 
 
 RGP FITTING
 

Topical anaesthetic use prior to RGP lens fitting
To investigate the effect of topical anaesthetic (TA) during rigid gas-permeable (RGP) CL fitting on subjective and objective measures of patient anxiety, Gill et al conducted this prospective, randomised, double-masked study among 47 subjects at two visits scheduled one week apart. Use of TA in RGP CL fitting was shown to be a clinically safe practice that may enhance first RGP CL experience especially in anxious patients, reduce anxiety during the adaptation period, and reduce anxiety prior to subsequent RGP CL wear.

Cont Lens Anterior Eye 2017;DOI: http://dx.doi.org/10.1016/j.clae.2017.07.005. Click here for full text
 
 
 
 
 
 OPTICS
 

Accommodative behaviour of eyes wearing aspheric CLs
To examine the accommodative response of young eyes wearing aspheric single-vision CLs, Altoaimi et al measured accommodation behaviour in eight young adult eyes using the Shack-Hartmann aberrometer. Near vision pupil miosis was sufficient to counteract the increasing negative spherical aberration induced by the accommodating crystalline lens. Aspheric CLs designed to correct some or all of the unaccommodated eye’s positive spherical aberration do not interfere with accommodation.

Optom Vis Sci 2017;94:10 971-980. Click here for abstract

 
 
 
 
 
 PRESBYOPIA
 

Intracorneal inlays for correction of presbyopia
In this review article, Binder analyses the history and development of various inlay approaches designed to correct presbyopia. Recent surgical approaches include intracorneal inlays. Inlay approaches include increasing corneal curvature alone, implanting a multifocal inlay, or implanting a small-aperture device that functions as a pinhole to restore unaided near and intermediate visual acuity. Unlike other refractive surgical approaches, these newer techniques are removable. Technological advancements have produced predictable and safer clinical results compared with previous intracorneal inlays.

Eye & Contact Lens 2017;43:5 267-275. Click here for abstract
 
 
 
 
 
For more information on Research Update visit www.iacle.org.
 
 
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Research Update Issue 9


September 2017  
 
 
 
 

Welcome to our monthly research update
 
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
 
More information on Research Update and how to use it in your contact lens teaching here. Access archived issues via Member Login under Research.
 
 
 
Issue 9 – September 2017
 
Mucin balls are in the spotlight again this month. In this issue, we look at the microstructural characteristics of mucin balls and their correlation with ocular surface properties. We also include a study that investigates tear cytokine levels in lens wearers with Acanthamoeba keratitis.

Contact lens material properties are also highlighted. Could hyaluronan be incorporated into hydrogels as a built-in lubricant? And does lipid deposition differ between combinations of lenses and lens care solutions? An Australian group examines tear film biochemistry of symptomatic and asymptomatic lens wearers. American researchers report on compliance and patient responses to eyelid hygiene. And finally, we describe a fascinating study that explores the association between constricted living space in Hong Kong and myopia development.

Enjoy!
The IACLE Education Team
 
 
 
Journals reviewed in this issue  

  JOURNAL VOLUME AND ISSUE NUMBER
 
  Contact Lens & Anterior Eye 40:5
  Cornea 36:7
  Journal of Biomedical Materials Research B Early view
  Optometry and Vision Science 94:9
  Eye & Contact Lens 43:4
  Ophthalmic & Physiological Optics 37:5
 
 
 
 
 
 OCULAR RESPONSE
 

Microstructural evaluation of mucin balls
Grupcheva et al conducted this prospective, comparative analysis of two groups of patients, continuously wearing silicone hydrogel lenses for therapeutic (20 eyes) or optical (22 eyes) purposes. Clinical examination was reinforced with laser scanning in vivo confocal microscopy, and qualitative analysis of mucin balls included shape and reflectivity. Mucin balls affected the corneal surface at microstructural level including transient epithelial alteration and keratocyte activation. The main predisposing factor for mucin ball formation appeared to be irregular ocular surface.

Cont Lens Anterior Eye 2017;40:5 340-345 Click here for full text
 
 
 
 
 
 OCULAR RESPONSE
 

Tear cytokine levels in Acanthamoeba keratitis
Carnt et al conducted this prospective study of CL wearers with Acanthamoeba keratitis (AK) to determine differences in key tear film cytokines between mild and severe cases of AK and control CL wearers. Basal tear specimens were collected by 10mL capillary tubes and tear protein levels were measured (132 tear samples from 61 AK cases – 15 severe and 46 mild/moderate – and 22 controls). Profiling patients with AK during disease showed differences in cytokine levels between severe and milder disease that may help clinical management.

Cornea 2017;36:7 791-798. Click here for abstract
 
 
 
 
 
 MATERIALS
 

Hydrogel lubrication with bulk incorporated hyaluronan (HA)
The objective of this experiment conducted by Samson et al was to assess the effect of crosslinked HA into the bulk of model CL materials on (a) surface wettability, (b) protein sorption, and (c) boundary lubricating properties, both alone and synergistically with PRG4 in solution. Surface wettability was assessed by water contact angle measurement, protein sorption by lysozyme sorption assay, and boundary lubricating properties using an in vitro friction test method. HA incorporation can reduce friction of hydrogels alone and in combination with PRG4 in solution.

J Biomed Mater Res B 2017; DOI: 10.1002/jbm.b.33989. Click here for abstract
 
 
 
 
 
 DEPOSITS
 

Lipid deposition on soft CLs with contemporary solutions
To determine the effect of lens/care system combinations on levels of lipid deposits, Babaei Omali et al recruited 236 experienced spherical soft CL wearers. Combinations of three CL and four CL care solutions were investigated. The study did not demonstrate conclusively that any of the solution/ CL combinations was superior to any of the other combination for amounts of lipid deposition. This limits the ability to make specific recommendations regarding lens care solution-CL material combinations. The possibility remains that certain lipid deposits may allow for greater comfort during wear.

Optom Vis Sci 2017;94:9 919-927. Click here for abstract
 
 
 
 
 
 TEAR FILM
 

Tear film biochemistry of lens wearers
To quantify concentrations of tear lipids and proteins in CL wearers, Masoudi et al recruited 45 (22 symptomatic and 23 asymptomatic) healthy, adapted wearers. Proteins were assayed using selected reaction monitoring mass spectrometry and enzyme immunoassay kits were used to measure prostaglandins, leukotriene B4 (LTB4), and cysteinyl leukotrienes. On a scale of 1 to 100, average comfort was above 70 for asymptomatic and equal or below 70 for symptomatic group. LTB4 was significantly higher in symptomatic CL wearers compared to asymptomatic wearers, which may partly mediate their discomfort response.

Optom Vis Sci 2017;94:9 914-918. Click here for abstract
 
 
 
 
 
 COMPLIANCE
 

Compliance and patient responses to eyelid hygiene
This cross-sectional study by Alghamdi et al assessed patient compliance with lid hygiene and which factors predict a favourable symptomatic response to treatment. Investigators assessed dry eye symptoms and lid margin signs, then instructed patients to perform warm compresses and lid scrubs. A follow-up phone survey assessed compliance and subjective therapeutic response after 6 weeks. Patients who self-reported dry eye symptoms at the first visit were more likely to be compliant with lid hygiene than those who did not report symptoms. Patients who performed the routine noted improvement in symptoms.

Eye & Contact Lens 2017;43:4 213-217. Click here for abstract
 
 
 
 
 
 MYOPIA
 

Constricted living space and myopia development in children
Choi et al investigated whether the crowded habitat in Hong Kong is associated with refractive error among children. Information such as demographics, living environment, parental education and ocular status were collected using parental questionnaires. Ocular axial length and refractive status of all 1,075 subjects from 12 schools were measured. Axial length in children and childhood refractive error were associated with high population density and small home size. A constricted living space may be an environmental threat for myopia development in children.

Ophthalmic Physiol Opt 2017;37:5 568-575. Click here for full text
 
 
 
 
 
For more information on Research Update visit www.iacle.org.
 
 

 

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Research Update Issue 8


August 2017  
 
 
 
 

Welcome to our monthly research update
 
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
 
More information on Research Update and how to use it in your contact lens teaching here. Access archived issues via Member Login under Research.
 
 
 
Special Issue – August 2017
 
The TFOS Dry Eye Workshop II

CLICK HERE FOR AN INTRODUCTION AND HERE FOR INFORMATION FROM TFOS ON TRANSLATIONS INTO MULTIPLE LANGUAGES

Since publication of the first TFOS DEWS report 10 years ago, the number of publications relating to dry eye has almost doubled. This reflects the enormous amount of work being done in this area and warranted an upgrading of the first report.

Two years of work by 12 subcommittees, made up of 150 experts from 23 countries, has been published by the Tear Film and Ocular Surface Society as the TFOS DEWS II Report. The report is published in The Ocular Surface and is also available via the TFOS website.

The objectives of the workshop were to:

  • Update the definition, classification and diagnosis of dry eye disease (DED)
  • Critically assess the etiology, mechanism, distribution and impact of this disorder
  • Address its management and therapy

Dry eye was identified as a disease for the first time during the TFOS DEWS I. The new definition of DED includes the phrase ‘loss of homeostatis’. The revised definition states:

  • Dry eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles.

Here are some excerpts from the report.
The IACLE Education Team
 
 
 
Journals reviewed in this issue  

  JOURNAL VOLUME AND ISSUE NUMBER
 
  The Ocular Surface 15:3
 
 
 
 
 
 SEX, GENDER AND HORMONES
 

Men vs women
While they play a major role in the regulation of the ocular surface and adnexal tissues, and in the difference in DED prevalence between men and women, further research is needed to clarify the precise nature, extent, and mechanisms of these sex, gender, and endocrine effects on the eye in health and disease. A deeper understanding of these issues may result in improved, more tailored and appropriate options for the treatment of DED.

Ocul Surf 2017;15:3 284-333. Click here for full text
 
 
 
 
 
  EPIDEMIOLOGY
 

Prevalence and risk factors
The prevalence of DED, with and without symptoms, ranges from 5% to 50%. Prevalence of DED based on signs only is even more variable, reaching up to 75% in some populations. Asian ethnicity appears to be a risk factor, but the reason for this is, as yet, unclear. Higher rates of DED in women compared to men only become significant with increasing age. The most severe economic impact of DED likely results from indirect costs related to decreased work productivity. Future needs include a detailed evaluation of the prevalence of DED of varying severity, prevalence in youth, incidence studies in various populations, and the impact of the use of current technologies, such as mobile devices.

Ocul Surf 2017;15:3 334-365. Click here for full text
 
 
 
 
 
 TEAR FILM
 

Structure and measurement
Evidence continues to support the more contemporary two-phase model of the tear film, with a lipid layer overlying a muco-aqueous phase. While tear proteins are reported to change in DED, no definitive set of proteins or changes in protein levels have been validated to aid in diagnosis. There is a need to further characterize the biochemistry of the tear film and for ways to dynamically measure tear film osmolarity and markers of inflammation over the whole ocular surface.

Ocul Surf 2017;15:3 366-403. Click here for full text
 
 
 
 
 
 PAIN AND SENSATION
 

Role of cold receptors
Cold thermoreceptors continuously discharge nerve impulses at the normal ocular surface temperature, responding to warming or cooling and to osmolarity increases, likely contributing to reflex control of basal tear production and blinking. Studies to date suggest potential merit in exploring treatment strategies involving cold receptors to manage DED symptoms.

Ocular Surface 2017;15:3 404-437. Click here for full text
 
 
 
 
 
 PATHOPHYSIOLOGY
 

Hyperosmolarity: hallmark of DED
Meibomian gland dysfunction (MGD) and Sjögren and non-Sjögren lacrimal disease remain leading causes of evaporative and aqueous-deficient DED, respectively. The core mechanism of DED is tear hyperosmolarity, which is the hallmark of the disease. It damages the ocular surface both directly and by initiating inflammation. The role of increased friction in DED and its subsequent sequelae deserves further investigation. Improved understanding of the role of subclinical inflammation in the early stages of DED also warrants further study.

Ocular Surface 2017;15:3 438-510. Click here for full text
 
 
 
 
 
 IATROGENIC DRY EYE
 

Medications, CLs and other interventions
Topical and systemic medications, contact lenses, ophthalmic surgeries, and non-surgical procedures can cause DED. Future recommendations for research include conducting further epidemiological studies to better define risk factors, creating less toxic medications and preservatives, devising less invasive ophthalmic procedures, and developing strategies for the detection of early DED prior to surgical interventions.

Ocular Surface 2017;15:3 511-538. Click here for full text
 
 
 
 
 
 DIAGNOSTIC METHODOLOGY
 

Identifying DED
If DED is suspected, a positive result to a screening questionnaire such as the 5-item Dry Eye Questionnaire (DEQ-5) or the Ocular Surface Disease Index (OSDI) should trigger further evaluation, with tear break-up time (non-invasive methods preferred), tear film osmolarity determination, and ocular surface staining (that includes the cornea, conjunctiva and lid margin) with fluorescein and lissamine green. Identification of a disruption in tear film homeostasis with these tests allows a diagnosis of dry eye to be made. Other tests, such as meibography, lipid layer interferometry, evaporation and tear volume measurements can help clarify where the individual with DED falls on the evaporative and aqueous-deficient DED subtype classification spectrum.

Ocular Surface 2017;15:3 539-574. Click here for full text
 
 
 
 
 
 MANAGEMENT AND THERAPY
 

 
Restoration of tear film homeostasis is the ultimate goal in the management of DED. Determining whether the major cause(s) of an individual’s DED pertains predominantly to aqueous tear deficiency or to evaporative causes, or both, is critical in helping select the most appropriate management strategy. Although staged management and treatment recommendations are presented, the heterogeneity of the DED patient population mandates that practitioners manage and treat patients based on individual profiles, characteristics and responses.

Ocular Surface 2017;15:3 575-628. Click here for full text
 
 
 
 
 
For more information on Research Update visit www.iacle.org.
 
 

 

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Research Update Issue 7


July 2017  
 
 
 
 

Welcome to our monthly research update
 
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
 
More information on Research Update and how to use it in your contact lens teaching here. Access archived issues via Member Login under Research.
 
 
 
Issue 7 – July 2017
 
One group of ametropes is arguably less well understood than others: those with astigmatism. In this issue, we look at how different types of astigmatism influence visual acuity and also the possibility of estimating total corneal astigmatism from anterior corneal data.

An Australian research group investigates changes in corneal sensitivity and nerve morphology in orthokeratology. Two reviews look at the effects of refractive interventions on the cornea. A study from China examines changes in tear film and blink pattern after corneal refractive surgery. We also seek an answer to the often-asked practical question: ‘What is the ideal contact lens cessation time prior to corneal refractive surgery?’ And finally, we report a study that explores the impact of increasing myopia on central corneal nerve density.

Enjoy!
The IACLE Education Team
 
COMING SOON: our review of the new TFOS DEWS II Report, now available via The Ocular Surface here and on the TFOS website here
 
 
 
Journals reviewed in this issue  

  JOURNAL VOLUME AND ISSUE NUMBER
 
  Journal of Optometry 10:3
  Cornea 36:7
  Eye & Contact Lens 43:4
  Contact Lens & Anterior Eye Articles in Press
  Ophthalmic & Physiological Optics 37:4
 
 
 
 
 
 ASTIGMATISM
 

Influence of type of astigmatism on VA
To investigate change in visual acuity (VA) produced by different types of astigmatism (power and orientation of principal meridians) on normal, accommodating eyes, Remón et al used the lens-induced method to simulate astigmatic blur conditions on healthy emmetropic eyes. VA correlated with blur strength in a different way for each type of astigmatism, depending on accommodative demand. VA is better when one of the focal lines lies on the retina irrespective of the axis orientation, while accommodation favors this situation.

Journal of Optometry 2017;10:3 141-148. Click here for full text
 
 
 
 
 
 ASTIGMATISM
 

Estimating corneal astigmatism from anterior corneal data
Næser et al reviewed the records of 951 patients examined with Pentacam high-resolution Scheimpflug camera to determine keratometric astigmatism (KA), posterior corneal astigmatism (PCA), and total corneal astigmatism (TCA), and to establish a model for estimating TCA from anterior corneal data. They found a strong linear correlation (r2 = 0.90) between KA and TCA meridional powers. TCA could be accurately estimated from anterior corneal data with a new formula. Applications include toric intraocular lens calculation.

Cornea 2017;36:7 828-833. Click here for abstract
 
 
 
 
 
 ORTHOKERATOLOGY
 

Corneal sensitivity and nerve density in Ortho-K
This cross-sectional study by Lum et al looked at changes in corneal sensitivity and nerve morphology in orthokeratology (OK) contact lens wear. Corneal sensitivity, nerve morphology and nerve fiber density (NFD) of 54 subjects grouped in three categories (no lens wear, soft lens wear and OK wear) were measured. There was a significant difference in corneal sensitivity between the three groups. Long-term OK lens wear was associated with a decrease in central corneal sensitivity and NFD. Corneal nerves play an important role in the blink reflex and tear production.

Eye & Contact Lens 2017;43:4 218-224. Click here for abstract
 
 
 
 
 
 REFRACTIVE SURGERY
 

Tear film instability after corneal refractive surgery…
In this study Chen et al investigated associations between changes in tear film instability and the lipid layer thickness (LLT) and blink pattern after corneal refractive surgery (CRS). The LLT and blink pattern of 40 patients were evaluated, one week before and 30 days after CRS. The authors conclude that the LLT and blink pattern are involved in maintaining tear film stability after CRS. Artificial tears containing lipids, and well directed blink training, might be beneficial to maintain tear film stability after CRS.

Cornea 2017;36:7 810-815. Click here for abstract

 
 
 
 
 
 REFRACTIVE SURGERY
 

…and effects of soft CL wear prior to surgery
To examine the influence of previous soft contact lens (SCL) wear on corneal refractive surgery (CRS) outcomes, Lloyd-McKernan et al reviewed patient records for two groups of LASIK and LASIK/PRK patients: those who ceased SCL wear for two weeks or for 24h prior to CRS. CRS outcomes (efficacy, predictability, VA and refractive error) were compared pre-operatively and one and six months post-operatively. Previous SCL wear had no negative impact on visual outcomes compared with a non-CL control group, regardless of previous SCL cessation time. Longer cessation times may be advisable for hyperopic SCL wearers.

Cont Lens Anterior Eye 2017; http://dx.doi.org/10.1016/j.clae.2017.05.009. Click here for full text

 
 
 
 
 
 MYOPIA
 

Corneal nerve density in myopia
Harrison et al explored the impact of increasing myopia on central corneal nerve density by comparing sub basal nerve plexus density measured by confocal microscopy. Corneal nerves of 70 healthy adult subjects aged 21-50 years were imaged over the central cornea with a Nidek CS4 confocal microscope. Nerves were evaluated using the NeuronJ program for density calculation. Corneal nerve density in the sub-basal plexus decreased with increasing myopia, a noteworthy finding for corneal surgery and contact lens wear.

Ophthalmic Physiol Opt 2017;37:4 297-304 Click here for abstract
 
 
 
 
 
For more information on Research Update visit www.iacle.org.
 
 
Posted on

Research Update Issue 6


June 2017  
 
 
 
 

Welcome to our monthly research update
 
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
 
More information on Research Update and how to use it in your contact lens teaching here. Access archived issues via Member Login under Research.
 
 
 
Issue 6 – June 2017
 
Strategies to control the progression of myopia continue to be a focus for current research. In this issue, we take a look at the intriguing association between time spent outdoors and development of myopia, and also the efficacy vs adverse effects of atropine in myopic children.

With increasing interest in fitting children with soft contact lenses, we present a timely review of studies that estimate the incidence of corneal infiltrative events and microbial keratitis in children. Two studies look at other ocular responses to soft lens wear: changes to limbal topography and ocular surface inflammation. And finally we report on visual acuity and quality of life in dry eye disease.

Happy reading!
The IACLE Education Team
 
 
 
Journals reviewed in this issue  

  JOURNAL VOLUME AND ISSUE NUMBER
 
  Acta Ophthalmologica Early view
  JAMA Ophthalmology 135:6
  Optometry & Vision Science 94:6
  Contact Lens & Anterior Eye Articles in Press
  The Ocular Surface 15:2
 
 
 
 
 
 MYOPIA
 

Outdoor time: role in myopia prevention and control
To evaluate the evidence for an association between time outdoors and risk of developing myopia, Xiong et al conducted a systematic review followed by a meta-analysis and a dose–response analysis of 25 relevant research papers. They found a significant protective effect of outdoor time for incident myopia. Increased time outdoors is effective in preventing the onset of myopia as well as in slowing the myopic shift in refractive error. However, outdoor time was not effective in slowing progression in eyes that were already myopic.

Acta Ophthalmol 2017; DOI: 10.1111/aos.13403. Click here for full text
 
 
 
 
 
  MYOPIA
 

Atropine in childhood myopia therapy
In this meta-analysis, to evaluate the efficacy vs adverse effects of various doses of atropine as myopia therapy in children, Gong et al included 19 studies (randomised clinical trials and cohort studies) that examined 3,137 children. All doses of atropine were equally beneficial with respect to myopia progression. High-dose atropine (0.5% to 1.0%) was associated with more adverse effects, such as a 43% incidence of photophobia, compared with 6% for low dose (0.01%) and 18% for moderate dose (>0.1% to <0.5%). The findings suggest that efficacy of atropine is dose independent, whereas the adverse effects are dose dependent.

JAMA Ophthalmol 2017; 135:6 624-630. Click here for abstract
 
 
 
 
 
 COMPLICATIONS
 

Are soft contact lenses safe for children?
To estimate the incidence of corneal infiltrative events and microbial keratitis in soft lens wearers under the age of 18 years, Bullimore reviewed and summarized a broad range of studies including large-scale epidemiological studies, hospital-based case series, long- and short-term prospective studies, and multicenter retrospective studies. None of the nine prospective studies reported any cases of microbial keratitis. The incidence of corneal infiltrative events in children was found to be no higher than in adults, and in the age range of 8 to 11 years, it may be markedly lower.

Optom Vis Sci 2017;94:6 638-646 Click here for full text
 
 
 
 
 
 OCULAR RESPONSE
 

Limbal changes following soft lens wear
Consejo et al conducted a prospective study to assess whether short-term soft contact lens (SCL) wear affects the anterior ocular surface. Twenty-two subjects were imaged using a corneo-scleral profilometer. Measurements were obtained without lens wear (baseline), immediately after lens removal following 5h of wear and 3h after lens removal. Six types of daily disposable CLs were considered. Short-term SCL wear significantly modified corneo-scleral limbal radius and the changes were repeatable. Assessing topographical limbus after CL wear could be a tool to optimize lens selection.

Cont Lens Anterior Eye 2017; DOI: http://dx.doi.org/10.1016/j.clae.2017.04.007. Click here for full text
 
 
 
 
 
 OCULAR RESPONSE
 

Measuring ocular surface inflammation
Chao et al reviewed non-invasive contemporary techniques for detecting inflammatory responses in SCL wearers. More than 1,500 proteins have been identified on the ocular surface and tear film. Among them, at least 25 inflammatory mediators can be detected in tears in healthy subjects. Tear analysis of inflammatory mediators is relatively less invasive and requires few collection and extraction procedures. Possible methods to collect tears include microcapillary tubes, Schirmer strips and microsponges. Apart from tear analysis, conjunctival cells have been used to assess the ocular surface inflammatory responses.

Cont Lens Anterior Eye 2017; DOI: http://dx.doi.org/10.1016/j.clae.2017.05.008. Click here for full text

 
 
 
 
 
 DRY EYE
 

Visual acuity and quality of life in dry eye disease
This article by Benítez-del-Castillo et al was developed from a meeting of the OCEAN group. The effects of dry eye disease (DED) on visual acuity result in difficulties with driving, reading and computer use, and negatively impact psychological health. Patients with DED often have poor quality of life (QoL). This may be due to both the physical effects of DED, such as ocular discomfort, and decreased visual function. Clinicians should consider the impact of decreased visual function, which needs to be measured dynamically, and the impact on QoL.

Ocul Surf 2017;15:2 169-178. Click here for abstract
 
 
 
 
 
For more information on Research Update visit www.iacle.org.
 
 
Posted on

Research Update Issue 5


May 2017  
 
 
 
 

Welcome to our monthly research update
 
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
 
More information on Research Update and how to use it in your contact lens teaching here. Access archived issues via Member Login under Research.
 
 
 
Issue 5 – May 2017
 
Many contact lens experts are intrigued by keratoconus and its management. In this issue, we present two systematic reviews on treatments for keratoconus, especially highlighting corneal collagen cross-linking.
In other reviews, a study conducted in Hong Kong evaluates the effect of discontinuation of orthokeratology on eyeball elongation. A research group from Spain reports on the success of rigid gas-permeable lens fits for refractive and therapeutic reasons. We include a study that tests the hypothesis that sleep position may affect dry eye and meibomian gland dysfunction. And finally, a comparison of theoretically optimized bifocal contact lens designs to those commercially available suggests that these designs should be prototyped and tested in a clinical setting.

Happy reading!
The IACLE Education Team
 
 
 
Journals reviewed in this issue  

  JOURNAL VOLUME AND ISSUE NUMBER
 
  Eye & Contact Lens 43:3
  Acta Ophthalmologica 95:3
  Contact Lens & Anterior Eye 40:2
  Cornea 36:5
  Ophthalmic & Physiological Optics 37:3
 
 
 
 
 
 KERATOCONUS
 

Keratoconus management: a review of treatment modalities
Mandathara et al conducted a systematic review of 241 articles on keratoconus (KC) management options from the past 20 years. About 41% of them were prospective case series; randomized controlled trials (RCTs) were limited to corneal collagen cross-linking (CXL). Contact lenses (CLs) were the mainstream of KC management and were associated with reversible and non-sight-threatening complications. Surgical procedures were generally associated with transient inflammatory events and permanent sequelae. High-quality, longer follow-up RCTs are required to evaluate the long-term effects of KC interventions.

Eye & Contact Lens 2017;43:3 141-154. Click here for abstract
 
 
 
 
 
 KERATOCONUS
 

Cross-linking in children with keratoconus
In this systematic review to determine the effectiveness of corneal collagen cross-linking (CXL) in children, McAnena et al analyzed 13 papers, examining 490 eyes of 401 patients with a mean age of 15.25 (+1.5) years. Nine papers were included in the meta-analysis. The review found that standard CXL may be effective in halting progression of keratoconus in pediatric patients at 1 year. However, larger, more long-term studies are required to ascertain its effectiveness.

Acta Ophthalmol 2017;95:3 229-239. Click here for abstract
 
 
 
 
 
 MYOPIA
 

Does axial elongation increase when ortho-k is discontinued?
This single-masked, prospective study was conducted by Cho & Cheung to evaluate changes in axial elongation, over a 14-month period, in subjects who discontinued (for 7 months) and then resumed orthokeratology lens wear. Significant increase in axial elongation was found in subjects when they discontinued lens wear. Stopping ortho-k lens wear at or before the age of 14 years led to a more rapid increase in axial length that slowed again with resumed lens wear after 6 months.

Cont Lens Anterior Eye 2017;40:2 82-87. Click here for full text
 
 
 
 
 
 FITTING
 

Success of RGPs: refractive and therapeutic fittings
To evaluate the success of rigid gas permeable (RGP) contact lens (CL) fitting, Ortiz-Toquero et al retrospectively analyzed 232 new fits, of which 166 were refractive fittings (71.6%) and 66 therapeutic (28.4%). Of the refractive fittings, 88 subjects (53%) were initially fitted with RGP CLs and 61 (69.3%) of them met the success criteria. Of the therapeutic fittings, 61 subjects (92.4%) were initially fitted with RGP CLs and 59 (96.7%) of these were successful. A relatively high percentage of successful RGP fits was achieved for refractive (7/10 subjects) and even higher for therapeutic (9/10 subjects) prescriptions.

Eye & Contact Lens 2017; 43:3 168-173. Click here for abstract
 
 
 
 
 
 DRY EYE
 

EYE Effect of sleep position on ocular surface
To validate their observation that sleep position in some cases may significantly affect dry eye and meibomian gland dysfunction (MGD), Alevi et al conducted this cross-sectional, non-interventional, single-masked study involving 100 study patients and 25 in a control group. The Ocular Surface Disease Index score was found to be elevated in patients who slept on their sides or face down as opposed to on their backs. In addition to treatment, changing sleep pattern to a supine position may lead to improvement of patients’ disease.

Cornea 2017;36:5 567-571. Click here for abstract

 
 
 
 
 
 OPTICS
 

Commercial vs theoretically optimized CLs for presbyopia
To compare optical designs of theoretically optimized bifocal CLs to those of commercially available designs for presbyopia, Legras & Rio simulated retinal images using a numerical eye model and tested 10 optical designs – 4 commercially available and 6 optimized. Twenty subjects graded the quality of simulated images. Commercial contact lens profiles did not give an image quality and depth-of-focus as good as the theoretically optimized optical designs. The best bifocal profiles were those with 5 and 8 concentric zones. Inter-individual variations were observed for all profiles.

Ophthalmic Physiol Opt 2017;37:3 297-304 Click here for abstract
 
 
 
 
For more information on Research Update visit www.iacle.org.
 
 
Posted on

Research Update Issue 4


April 2017  
 
 
 
 

Welcome to our monthly research update
 
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
 
More information on Research Update and how to use it in your contact lens teaching here. Access archived issues via Member Login under Research.
 
 
 
Issue 4 – April 2017
 
Physiological response to contact lens wear is a fascinating topic and worth revisiting. In this issue, we take a look at the corneal endothelial response to RGP lens wear and also investigate the relationship between mucin balls and corneal infiltrative events.

A research group in the US surveys practitioner reports of ocular complications in patients wearing decorative contact lenses purchased through unauthorized sellers. Another survey compares vision correction preferences of non-presbyopes and presbyopes. We also include a study that tests the hypothesis that tear break-up (TBU) presents a direct noxious stimulus to the ocular surface. And we report on the effect of multifocal contact lenses on disability glare by means of ocular straylight.

Happy reading!
The IACLE Education Team
 
 
 
Journals reviewed in this issue  

  JOURNAL VOLUME AND ISSUE NUMBER
 
  Contact Lens & Anterior Eye 40:2 and Articles in Press
  Optometry & Vision Science 94:4
  Eye & Contact Lens 43:2
  The Ocular Surface Articles in Press
 
 
 
 
 
 OCULAR RESPONSE
 

Corneal endothelium in RGP lens wearers
To assess whether polymegethism and pleomorphism were evident after medium-term rigid gas permeable (RGP) CL wear, Doughty conducted a cross-sectional, observational study following 46 subjects over 12 years. Compared to a historical database, most endothelia (37/46) showed some changes. Endothelial polymegethism appeared to be a consequence of RGP lens wear with the magnitude of change related to the cumulative duration of wear.

Cont Lens Anterior Eye 2017;40:2 109-115. Click here for full text
 
 
 
 
 
 OCULAR RESPONSE
 

Mucin balls and corneal infiltrative events
A randomized clinical trial was nested within a cohort study by Szczotka-Flynn et al to determine whether mucin ball (MB) formation is protective against corneal infiltrative events (CIEs). Of 282 participants, 218 entered phase 2, i.e. randomized trial, during which 33 CIEs occurred. Repeated, longer-term MB presence did not significantly reduce the incidence of CIEs; however, it significantly decreased the rate of CIEs by 62%. The hypothesis that MB formation is protective against CIEs throughout extended wear was not supported.

Optom Vis Sci 2017; 94:4 448-457. Click here for full text
 
 
 
 
 
 COMPLICATIONS
 

Decorative CLs purchased through unauthorized sellers
Gaiser et al reported results of a survey completed by 22 optometrists regarding ocular complications in patients wearing decorative CLs. Concurrently, the authors evaluated 18 independent, online decorative CL sellers. A majority of respondents (77%) reported having patients with complications from decorative CLs. The most common age group for complications was 18 to 25 years (61%). A quarter of the lenses were purchased illegally. Of the 18 online sites examined, 72% of sellers failed to adhere to FTC and FDA regulations. The authors call for better regulation and oversight of unlicensed vendors.

Eye Contact Lens 2017;43:2 135-139. Click here for abstract
 
 
 
 
 
 PRESBYOPIA
 

Challenging assumptions about presbyopes and CLs
This prospective, cross-sectional study was conducted by Rueff and Bailey to survey opinions on refractive correction among adults wearing spectacles or CLs (n=304). There was no difference in the proportion of presbyopes and non-presbyopes who had tried CLs or who would prefer to wear CLs. Presbyopes and non-presbyopes had similar opinions about spectacles and CLs. Eye care practitioners should not assume that presbyopia, refractive error, or gender are factors that preclude a patient from being interested in CLs.

Cont Lens Anterior Eye DOI: http://dx.doi.org/10.1016/j.clae.2017.03.010. Click here for full text

 
 
 
 
 
 TEAR FILM
 

Tear break-up and symptoms of ocular irritation
Zhang et al tested the hypothesis that tear break up (TBU) presents a direct noxious stimulus to the ocular surface. Ten subjects kept one eye open as long as possible, termed sustained tear exposure (STARE), while discomfort was monitored with and without a CL in place. Discomfort was significantly higher during trials without a CL. TBU during STARE trials was associated with increased discomfort, which was partially blocked by a CL. This supports the hypothesis that TBU directly stimulates the corneal surface.

The Ocular Surface DOI: http://dx.doi.org/10.1016/j.jtos.2017.03.001. Click here for abstract
 
 
 
 
 
 OPTICS
 

Ocular straylight with multifocal CLs
To investigate the effect of multifocal CLs on disability glare by means of ocular straylight, Labuz et al conducted this prospective, randomized, comparative study in 16 subjects. Straylight was measured using a commercial straylight meter with the natural and dilated pupil, and measurements were repeated with a CL in situ after pupil dilation. After pupil dilation, straylight increased significantly. Straylight-pupil size dependency should be considered to avoid elevated straylight in multifocal CL wearers. Some types of multifocal might be more beneficial for some wearers, e.g. professional drivers, when straylight is taken into account.

Optom Vis Sci 2017;94:4 496-504 Click here for abstract
 
 
 
 
 
For more information on Research Update visit www.iacle.org.
 
 
Posted on

Research Update Issue 3


March 2017  
 
 
 
 

Welcome to IACLE’s monthly research update
 
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
 
More information on Research Update and how to use it in your contact lens teaching here. Access archived issues via Member Login under Research.
 
 
 
Issue 3 – March 2017
 
The effects of myopia correction on binocular vision are an area of interest for all eye care practitioners and for researchers. In this issue, we take a look at how orthokeratology in young adults, and soft multifocals in children, affect binocular vision function.
In other studies, a research group in Australia investigates spherical aberrations induced by multifocals and their impact on visual performance. We report on a study of anterior and posterior corneal astigmatism of normal and keratoconic eyes. One paper addresses a practical issue of fluorescein volumes and their effect on tear film stability. And a group in Thailand assesses knowledge and behavior in cosmetic CL wearers, and the presence of amoebae in lenses. Finally we also include a study that supports previous work on conjunctival microcirculation in response to CL wear.

Happy reading!
The IACLE Education Team
 
 
 
Journals reviewed in this issue  

  JOURNAL VOLUME AND ISSUE NUMBER
 
  Contact Lens & Anterior Eye Articles In Press
  Optometry & Vision Science 94:3, 94:2
  Cornea 36:4
  Eye & Contact Lens 43:2
 
 
 
 
 
 MYOPIA & BINOCULAR VISION
 

Ortho-K vs soft lens wear
To compare near point binocular vision function of young adult myopes wearing orthokeratology (OK) lenses to single-vision soft disposable contact lens (SCL) wearers, Gifford et al retrospectively analysed clinical records of 17 OK wearers (aged 18-30 years). Compared to matched SCL wearers, the OK group were significantly more exophoric and had better accommodation accuracy. More SCL wearers had high lags of accommodation and esophoria than OK wearers. Young adult myopes with specific binocular vision disorders may benefit from OK wear in comparison to single-vision SCL wear.

Cont Lens Anterior Eye 2017. Click here for full text

 
 
 
 
 
 MYOPIA & BINOCULAR VISION
 

Accommodation and phoria with multifocals
In this crossover study Gong et al aimed to determine the effect of multifocal contact lenses (MFCLs) on accommodation and phoria in children. Accommodative responses and phorias of 16 myopic children wearing single-vision (SV) and MFCLs (+2.50D center-distance add) were measured at four distances (>3m, 100cm, 40cm, 25cm). The authors found a small decrease in high and low illumination visual acuity, and contrast sensitivity with multifocals. Subjects were more exophoric with multifocals and had decreased accommodative responses at increasing accommodative demands.

Optom Vis Sci 2017;94:3 353-360. Click here for abstract
 
 
 
 
 
 OPTICS
 

Spherical aberration and multifocal performance
Fedtke et al investigated the impact of the primary (PSA) and secondary (SSA) spherical aberration on visual performance in 17 presbyopes wearing seven commercial lens types (four center-near MFCLs, one center-distance MFCL, one bifocal, one single-vision control). All test lenses induced significant amounts of PSA. Compared to the control, distance high- and low-contrast visual acuities, and contrast sensitivity, were significantly reduced with all test lenses. The findings may prove useful when designing new or optimizing existing MFCLs.

Optom Vis Sci 2017;94:2 197-207. Click here for abstract
 
 
 
 
 
 KERATOCONUS
 

Corneal surfaces in keratoconic eyes
To evaluate and compare power and axis orientation of anterior and posterior astigmatism, Shajari et al retrospectively examined 861 eyes of 494 patients with keratoconus, and 256 eyes of 256 healthy individuals. Magnitude of corneal astigmatism was 3.47±2.10D on the anterior surface and 0.69±0.40D on the posterior surface in keratoconic eyes. In eyes with keratoconus, posterior axis alignment of corneal astigmatism is in line with alignment of the anterior surface in a majority of cases.

Cornea 2017;36:4 457-462. Click here for abstract
 
 
 
 
 
 TEAR FILM
 

Less is more for fluorescein volume
Mooi et al compared tear film break-up time measurements of 41 subjects obtained non-invasively (NIBUT), with those measured following minimal (mTBUT) and conventional volumes (TBUT) of fluorescein instillation. Both NIBUT and mTBUT measurements were significantly longer than TBUT, while there were no significant differences between NIBUT and mTBUT. Both NIBUT and mTBUT measurements demonstrated a larger spread than those of TBUT, although NIBUT and mTBUT did not differ significantly. This suggests that minimising instilled volumes can reduce the impact of fluorescein on clinical measurements.

Cont Lens Anterior Eye. Click here for full text
 
 
 
 
 
 COMPLIANCE
 

Cosmetic lenses: knowledge, behavior and contamination
Mahittikorn et al surveyed 100 cosmetic contact lens (CCL) wearers to assess their knowledge and behavior of lens care. Their lenses were also tested for free-living amoeba (FLA) strains. The CCL wearers generally showed a moderate (47%) or good (35%) level of knowledge, and good (51%) or excellent (40%) use of CCLs. Two CCL samples were positive for Acanthamoeba genotype T3 (wearer used saline for treating lenses) or Vahlkampfia (wearer used CCL while swimming). The public should be aware of CCL contaminated with potentially pathogenic FLA that can cause keratitis.

Eye Contact Lens 2017;43:2 81-88. Click here for abstract
 
 
 
 
 
 OCULAR RESPONSE
 

Conjunctival microcirculation in contact lens wear
Chen et al determined blood flow velocities and corresponding vessel diameters to characterize the response of the bulbar conjunctival microvasculature to contact lens wear. They used an adapted slit lamp to image the temporal bulbar conjunctiva of 22 healthy subjects before and after 6h of soft CL wear. Average blood flow velocity increased from 0.51+0.20 to 0.65+0.22 mm/sec after 6h of wear. Blood flow velocity distribution showed a velocity increase that correlated with vessel diameter increase from baseline.

Eye Contact Lens 2017;43:2 95-99. Click here for abstract
 
 
 
 
For more information on IACLE Research Update visit www.iacle.org.
 
 
Posted on

Research Update Issue 2

 

February 2017  
 
 
 
 

Welcome to our monthly research update
 
Welcome to Research Update, a new resource available to IACLE and BCLA members to support your teaching and practice. Each month we will send you a summary of some of the interesting findings appearing in peer-reviewed journals that month. Our aim is to help you keep up to date with the latest contact lens and anterior eye research, and to locate articles when you want to know more about a particular topic.
 
More information on Research Update and how to use it in your contact lens teaching here
 
 
 
Issue 2 – February 2017
 
In most countries around the world, hydrogels and silicone hydrogels account for an overwhelming majority of prescribed materials in contact lens practice. Yet we still have much to learn about their performance. In this issue, we take a look at some interesting new work in soft contact lenses.

A research group in the UK identifies factors associated with retention and dropout in the first year of CL wear, with surprising findings. Another study re-evaluates the inter-relationship of soft CL base curve radius, diameter and lens fit. An Australian team compares the performance of silicone hydrogel and hydrogel daily disposables. And we report on a new study assessing compliance with daily disposable lens replacement. We also include research that compares dry eye tests in older females and that reveals the interaction of bacteria in CL cases. Happy reading!
 
The IACLE Education Team
 
 
 
Journals reviewed in this issue  

  JOURNAL VOLUME AND ISSUE NUMBER
 
  Contact Lens & Anterior Eye 40:1
  Optometry & Vision Science Pre-publication
  Eye & Contact Lens Published ahead-of-print
  Investigative Ophthalmology & Visual Science 58:1
 
 
 
 
 
 DROPOUT
 

New wearers: when and why do they drop out?
To identify factors associated with retention and dropouts in first year of CL wear, Sulley et al reviewed records of 524 patients at 29 sites in this retrospective study. After 12 months, 74% were still wearing CLs. Of the 136 lapsed, 25% discontinued during the first month and 47% within 60 days. While handling and comfort were the most commonly cited performance-related reasons for discontinuing in new spherical lens wearers, visual problems were the most common among new wearers of toric and, in particular, multifocal CLs.

Cont Lens Anterior Eye 2017;40:1 15-24. Click here for full text
 
 
 
 
 
 FITTING
 

Re-evaluating soft lens fit
Using a mathematical model, Young et al evaluated the inter-relationship of soft CL base curve radius, diameter, and lens fit. The highest overall success rate (90%) was with an 8.60/14.2mm (BC/diameter) design. The recommended rules of thumb: for a 0.4 mm change in BC, change the diameter by 0.2 mm to maintain similar on-eye diameter. When changing diameter by 0.4 mm, a change in BC of 0.2 mm is required to maintain similar lens tightness.

Optom Vis Sci 2017; DOI: 10.1097/OPX.0000000000001048. Click here for abstract
 
 
 
 
 
 MATERIALS
 

Silicone hydrogels versus hydrogels
To compare subjective, objective and safety performance of silicone hydrogel (SiHy) with hydrogel (Hy) daily disposable CLs, Diec et al performed a retrospective analysis on 201 patients. In the Hy group, there was greater increase in limbal redness from baseline but less conjunctival staining and indentation compared to the SiHy group. Neither material showed superiority in comfort; adverse event rates were low with both types. However, SiHy materials should be considered for patients at risk of hypoxia-related complications.

Eye Contact Lens 2017;DOI: 10.1097/ICL.0000000000000363. Click here for abstract
 
 
 
 
 
 COMPLIANCE
 

Health beliefs and daily lens replacement
Livi et al conducted a multi-center survey to assess the compliance of daily disposable (DD) CL wearers with replacing lenses. Out of the 354 Italian respondents, 23% were non-compliant with manufacturer-recommended replacement frequency. The main reason for re-using DDCLs was ‘to save money’ (35%). It is important to warn DDCL wearers of the severity of a CL-related eye infection, and to underline the possibility of its prevention.

Cont Lens Anterior Eye 2017;40:1 25-32. Click here for full text
 
 
 
 
 
 DRY EYE
 

Comparing dry eye tests in older women
Ngo et al quantified the association of dry eye (DE) symptoms with diagnostic tests in older females. Twenty symptomatic females were age matched with 20 females without DE symptoms (age range 46-73 years). The tests most strongly associated with DE symptoms in older women were ocular staining, meibum quality, number of obstructed meibomian glands, and tear film stability. MGD was likely to be the main etiology of DE in this group.

Eye Contact Lens 2016; DOI: 10.1097/ICL.0000000000000344. Click here for abstract
 
 
 
 
 
 HYGIENE
 

Bacterial interactions in contact lens cases
To examine the interaction of commonly isolated bacteria from contact lens cases, Datta et al grew 4-5 strains each of the bacteria and allowed them to coaggregate for 24 hours. The study demonstrated, for the first time, that ocular isolates of P. aeruginosa and S. aureus could coaggregate. But this may not be related to buildup of biofilms in cases, as there was no evidence that coaggregation was associated with cohesion between the strains. The study also confirmed that P. aeruginosa can inhibit the growth of S. aureus.

Invest Ophthalmol Vis Sci 2017;58 50-58. Click here for full text
 
 
 
 
 
For more information on Research Update visit www.iacle.org.