Research Update

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.


The IACLE Education Team
Journals reviewed in this issue  

  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

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


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: Click here for full text


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


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


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


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: Click here for full text


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

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