Research Update Issue 27

March 2019

Welcome to our monthly research update

Research Update is a resource available exclusively to IACLE and BCLA members to support your teaching and practice. Each month we 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 27 – March 2019

In this issue we bring you various interesting topics related to clinical practice, ocular response and contact lens materials. Dropout has been a perennial concern in contact lens practice. A multi-site study evaluates ocular and lens factors associated with dropout.

Another study looks at the ocular surface of presbyopes wearing modern daily disposable multifocal lenses over a day’s wear. A Turkish group investigates anterior surface inflammation in silicone hydrogel lens wearers with or without meibomian gland dysfunction. And Iranian researchers describe microbial contamination in bandage contact lenses.

We include a couple of studies on material chemistry. An Egyptian group demonstrates release of silver nanoparticles from silicone hydrogel films for sufficient microbial activity. Other researchers examine uptake and release of polyvinyl alcohol from commercially available daily disposable lenses. Finally, we include a study that explores the need for customized multifocal contact lenses.

Happy Reading!

The IACLE Education Team

Journal reviewed in this issue

	JOURNAL	VOLUME AND ISSUE NUMBER
	Contact Lens & Anterior Eye	Articles in Press
	Eye & Contact Lens	45:1
	Cornea	38:2
	Optometry and Vision Science	96:3
	Ophthalmic and Physiological Optics	39:1

DROPOUT

Clinical factors associated with contact lens dropout

To determine ocular and lens factors associated with CL dropout, Pucker et al conducted this prospective, single-visit multi-site study among participants aged 18-45 years who had ceased CL wear within the past 6-12 months due to discomfort. Each subject was administered a symptoms survey and a study-specific survey. Clinical tests included detailed tear assessment. Dropouts were compared to currently successful CL wearers (56 pairs). Dry eye, meibomian gland (MG) plugging, upper eyelid meibum quality, and upper eyelid MG tortuosity significantly increased subjects’ odds of dropping out. Proactively treating MG dysfunction with eyelid hygiene may promote comfort and extra years of comfortable CL use.

Cont Lens Anterior Eye 2019. DOI: https://doi.org/10.1016/j.clae.2018.12.002. Click here for full text

PHYSIOLOGY

Response of the ageing eye to first day CL wear

In this prospective, non-randomized study, Lafosse et al investigated the ocular surface of an aged population wearing a water-gradient (delefilcon A) daily disposable CL over the first day of wear. Tear osmolarity, tear meniscus area (TMA), and ocular surface aberrations (total higher-order root mean square [RMS]) were assessed at baseline (t0), at 20min (t1) and after 8h (t2) of wear among 40 presbyopic subjects. No statistically signiﬁcant changes were found between t0, t1, and t2 for TMA, and between t0 and t2 for ﬂuorescein corneal and conjunctival staining. Tear breakup time worsened by the end of the day.

Eye & Contact Lens 2019;45:1 40-45. Click here for abstract

OCULAR RESPONSE

Inflammation in silicone hydrogel lens wearers

To determine whether silicone hydrogel contact lens (SH-CL) use, with or without meibomian gland dysfunction (MGD), promotes ocular surface inﬂammation, Yucekul et al recruited 80 patients in four categories (20 each) to this cross-sectional study: SH-CL users with clinical evidence of MGD (group 1), without MGD (group 2), CL-naive patients who had MGD (group 3), and who did not have MGD (group 4). All underwent tear function tests and cytokine evaluation. SH-CL use with concomitant MGD is not associated with cytokine-driven ocular surface inﬂammation but may affect tear function leading to dry eye symptoms. The presence of MGD should be monitored in CL wear.

Eye & Contact Lens 2019;45:1 61-66. Click here for abstract

BANDAGE LENSES

Microbiological evaluation of bandage contact lenses

This prospective study by Feizi et al aimed to describe microbiological contamination of bandage soft contact lenses used for management of persistent corneal epithelial defects and enrolled 57 consecutive eyes. Most bandage lenses (70.2%) used for this purpose did not show bacterial growth when placed in an enriched medium. Staphylococcus epidermidis was the most common microorganism isolated from the contaminated lenses. Infectious keratitis was not observed in any eyes.

Cornea 2019;38:2 146-150. Click here for abstract

MATERIALS

Silver nanoparticles and silicone hydrogel films

Mourad et al investigated the effects of silver nanoparticles (AgNPs) incorporated in silicone-hydrogel films on their physico-chemical properties and microbial activity. Silicone-hydrogel composite films (SiHCFs) were prepared by in-situ chemical reduction of silver ions added in different concentrations followed by ultraviolet (UV) casting. Physico-mechanical properties of the SiHCFs were evaluated and antimicrobial activity and biofilm formation of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus assessed. Incorporation of AgNPs into SiHCFs showed sufficient release of AgNPs to inhibit bacterial growth and reduce biofilm formation, with collateral enhancement of some mechanical properties.

Cont Lens Anterior Eye 2019. DOI: https://doi.org/10.1016/j.clae.2019.02.007. Click here for full text

MATERIALS

Uptake and release of PVA from contact lenses

The purpose of this study by Phan et al was to evaluate the uptake and release of polyvinyl alcohol (PVA) from three commercially available hydrogel contact lens materials (etafilcon A, omafilcon A, and nelfilcon A) replaced on a daily disposable basis. After 24h incubation in a 10-mg/mL solution of PVA, the lenses were evaluated using refractive index and an iodine-borate assay. The results suggest that the contact lenses tested in this study have similar efficiency in delivering PVA. These materials could be used to release the wetting agent for a short duration and potentially improve initial comfort.

Optom Vis Sci 2019;96:3 180-186. Click here for abstract

MULTIFOCALS

Could customization improve image quality?

Faria-Ribeiro & Gonzàlez-Mèijome looked at whether eyes with spherical aberration (SA) outside average levels underperform when ﬁtted with a simultaneous-imaging contact lens (CL) with a power proﬁle calculated for an ‘average eye’, and whether CL customization could improve image quality in these eyes. They used a statistical model of the wavefront aberration function of normal eyes to generate a vector of Zernike fourth-order SA coefﬁcients from 100 synthetic eyes. Findings confirmed the hypothesis and suggest that visual performance with multifocals can be improved by using a semi-customized approach.

Ophthalmic Physiol Opt 2019;39:1 37-45. Click here for full text

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