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Research Update

Welcome to our monthly Research Update, available exclusively to IACLE and BCLA members to support your teaching and practice.

Issue 41 – May 2020

As contact lenses are being recommended for myopia control, we begin this month’s issue with a review that addresses a pertinent question: how safe is contact lens wear in children? And a Danish group reports on the association between low physical activity, higher use of screen devices and myopia.

Researchers from China compare the efficacy and safety of two regimens of high myopia–partial reduction orthokeratology in children. We include a study that assesses the risk factors associated with contamination of lens cases in OrthoK lens wearers. Another explores the possibility of classifying keratoconus location based on keratometry or pachymetry.

A Taiwanese group studies the effects of lysosomal deposition on the friction coefficient of hydrogel contact lenses. And finally, we include an editorial that looks at the impact of silicone hydrogel lenses since their introduction 20 years ago. 

Happy reading!!

The IACLE Education Team

JOURNALS

Journals reviewed in this issue:

Acta Ophthalmologica  98:3

Eye & Contact Lens  46:3  

Contact Lens & Anterior Eye  43:2

Clinical and Experimental Optometry  103:3

RISK ANALYSIS

Safety of soft CLs for myopia control in children

In this retrospective review of six prospective, parallel-group, controlled, randomized clinical trials, Cheng et al examined the rate and types of ocular adverse events among children wearing soft contact lenses. A total of 581 myopic children (aged 7-15 years at baseline) dispensed daily disposable hydrogel lenses were included. No significant or serious ocular adverse events were reported. The incidence of contact lens-related events was 4.5 per 100 patient years. These data suggest daily disposable lenses can be safely worn by children.

Acta Ophthalmol 2020;98:3 e346-e351 DOI: 10.1111/aos.14283. Read the abstract

MYOPIA

Low physical activity, higher use of screen devices and myopia

To determine the prevalence of myopia in a Danish cohort aged 16-17 years, Hansen et al included 1,443 participants from the Copenhagen Child Cohort 2000 Eye Study which is a prospective, population-based, observational study. The prevalence of myopia was 25%. Lower physical activity and higher use of screen devices contributed significantly to the prevalence of myopia, with a roughly doubled risk of having myopia if physically active <3h/week or if using screen devices >6h/day.

Acta Ophthalmol. 2020: 98:3 e315-e321 DOI: 10.1111/aos.14242. Read the abstract

ORTHOKERATOLOGY

High myopia – partial reduction with OrthoK

Lyu et al conducted this prospective clinical study to compare the efficacy and safety of two OrthoK regimens with targets of 6D or 4D reduction. A total of 102 highly myopic children (aged 8-15 years) were recruited to three groups: OrthoK Group 1 (target myopia reduction of 6D); OrthoK Group 2 (target myopia reduction of 4D) and control group (single-vision spectacles). After 12 months, the two OrthoK regimens had similar effects in controlling the increase in axial length and refractive error. However, Group 1 had a higher rate of corneal staining that raises questions about its safety.

Eye & Contact Lens 2020; 46:3 141-146. Read the abstract

LENS CASE

Contamination of OrthoK lens cases

Wang et al recruited asymptomatic OrthoK wearers to evaluate the risk factors associated with contamination of lens cases in this group. A total of 194 lens cases were collected for analysis. Flat cases with ridges were the most heavily contaminated and cylindrical lens cases showed least contamination. The authors conclude that case design (cylindrical), monthly replacement, daily rinsing with multipurpose solution, and wiping with a tissue daily can effectively reduce biofilm formation in contact lens cases.

Cont Lens Anterior Eye 2020; 43:2 178-184. Read the full text

KERATOCONUS

Progression parameters of keratoconus

To assess the impact of classifying keratoconus location based on thinnest pachymetry or maximum keratometry (Kmax) on progression parameters after corneal crosslinking (CXL), Bardan et al followed up 43 patients (52 eyes) at one, three, six and 12 months after CXL, in this observational study. Keratoconus was classified as central, paracentral and peripheral based on X and Y co-ordinates of either thinnest pachymetry (Group 1) or Kmax (Group 2). The authors conclude that thinnest pachymetry and Kmax should not be used interchangeably when categorising keratoconus.

Clin Exp Optom 2020; 103:3 312-319. Read the abstract

HYDROGELS

Lysosomal deposition and friction coefficient of hydrogels

Su et al investigated the relationship between lysosomal deposition and the friction coefficient for three contact lenses (ocufilcon D, hefilcon A and nelfilcon A materials). In addition, the ability of the contact lens care solution to remove deposited lysozyme and provide lubrication for the lens was tested. Results showed that the care solution could reduce the increased friction coefficient caused by high lysosomal concentration. The authors propose a potential mechanism for these effects for certain types of hydrogel lenses.

Cont Lens Anterior Eye 2020; 43:2 144-148. Read the full text

SILICONE HYDROGELS

Two decades of silicone hydrogel lenses

In a personal perspective, Efron charts the impact of silicone hydrogel (SiHy) lenses on clinical practice over 20 years. SiHys were predicted to result in fewer hypoxic complications and to alleviate the problem of contact lens-associated keratitis (CLAK). While they have been successful in controlling hypoxic complications, they have had a partial impact on CLAK. The incidence of keratitis with SiHy and hydrogel lenses worn on an extended wear basis is similar in magnitude but the severity is greater with hydrogels. SiHys are expected to continue their domination of the contact lens market in the near future.

Clin Exp Optom 2020; 103:3 251-253. Read the full text

© International Association of Contact Lens Educators 2020

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