Research Update

Research Update Issue 25

January 2019

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 …

January 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 25 – January 2019

Presenting to you the first issue of 2019! We begin the new year with diverse topics in the field of contact lenses.

An Australian group highlights the differences between modern daily disposable multifocal soft contact lenses. We include a study that compares the effects of toric vs spherical lenses on visual performance. Another examines the relationship between water content and silicon content of silicone hydrogels. And a report from Ghana warns of microbial contamination of fluorescein solutions in multiple-use bottles.

Spanish researchers find that keratoconus onset has an impact on the whole anterior segment. Among contributions to a special issue on scleral lenses, a European group looks at how the anterior eye surface is affected by short-term miniscleral contact lens wear. Finally, we include a study that explores whether orthokeratology has a dose-response effect on axial length growth and reduces the interocular difference in axial length in anisomyopic children.

Happy reading!

The IACLE Education Team
Journal reviewed in this issue
Optometry and Vision Science 95:12, 96:1
Eye & Contact Lens 45:1
Clinical and Experimental Optometry 102:1
Contact Lens & Anterior Eye 41:6,
42:1 (Scleral Lens Special Edition)

Visual performance of daily disposable multifocal lenses
Sha et al recruited 72 presbyopes to this prospective, randomized, double-blind, crossover clinical trial. Three daily disposable simultaneous-vision multifocal soft lens types were fitted according to manufacturers’ guidelines and worn for 1 week. High- and low-contrast visual acuities were measured. Subjective performance was assessed (1-10 scales) for clarity, ghosting, driving vision, vision stability, ease of focusing, overall vision satisfaction and ocular comfort. BioTrue had better distance performance than near, whereas 1-Day Acuvue Moist performed conversely. Dailies AquaComfort Plus performed reasonably overall.

Optom Vis Sci 2018;95:12 1096-1104. Click here for abstract


Effect of toric vs spherical CLs on vision and eyestrain
In this subject-masked, randomized, cross-over study, Berntsen et al compared the effect of toric vs spherical soft contact lenses on objective measures of visual performance. Current soft CL wearers with -0.75 to -1.75D astigmatism in each eye were binocularly fitted with daily disposable toric and spherical CLs. High and low-contrast visual acuities were measured. Electromyography of the orbicularis oculi muscle was used to evaluate eyestrain. Toric CLs provided improved objective measures of vision in low-to-moderate astigmats.

Eye & Contact Lens 2019;45:1 28-33. Click here for full text


Silicone hydrogels: silicon, fluorine and water content
Dupre & Benjamin examined the relationship between water (W) content and silicon (Si) content of silicone hydrogel (SiHy) CL materials. SiHy materials were obtained from 16 CL brands. Fluorine (F) content was included in the analysis for the three materials containing a fluoropolymer. A fundamental negative linear relationship exists between Si and W contents for SiHys above 35% W content that is followed when F content and hydrogel coatings are empirically added to the analysis below 35% W content. The relationship between (Si+F) and W seems to be based on composition rather than structure of available SiHys.

Eye & Contact Lens 2019;45:1 23-27. Click here for abstract


Microbial contamination of multiple-use fluorescein
To investigate the possible microbial contamination of fluorescein sodium dye solutions used in eye clinics in Ghana, Kyei et al collected 21 samples of multiple-use fluorescein ophthalmic solutions from clinics (in-use) and 18 unopened bottles (yet to be used) from the same facilities. The solutions were inoculated in different culture plates. Microbial growth was identified using standard techniques. Positive cultures were recorded for all 21 multiple‐use bottles. Multiple-use bottles of fluorescein solution were contaminated with clinically important strains of bacteria and fungi.

Clin Exp Optom 2019;102:1 30-34. Click here for abstract


Anterior chamber parameters in keratoconus
Mas-Aixala et al investigated whether structural changes in keratoconus are predominantly corneal, limbal/scleral, or a combination of both, and possible differences between anterior segment meridians. A total of 84 eyes with keratoconus and 49 healthy eyes were included. Anterior chamber depth from the endothelium and corneal thickness, anterior chamber depth and sagittal depth (SAGT) from the epithelium, and distance from the end-point of SAGT to the anterior surface of the lens were measured. Keratoconus onset has an impact on the anterior segment as a whole, not only on corneal structures.

Cont Lens Anterior Eye 2018;41:6 538-541. Click here for full text


Anterior eye surface changes after miniscleral wear
To quantify the effect of short-term miniscleral CL wear on the anterior surface, Consejo et al fitted12 healthy subjects with a highly gas-permeable,16.5 mm diameter miniscleral worn for a 5h period. Topography-based corneo-scleral limbal radius estimates were derived from height measurements. Elevation differences in corneal and scleral regions were calculated and sclero-conjuctival flattening within different sectors analysed. A relatively short period of optimally fitted miniscleral lens wear in healthy eyes alters corneo-scleral and sclero-conjuctival topography but, on average, no significant corneal shape changes were found.

Cont Lens Anterior Eye 2019;42:1 70-74. Click here for full text


OrthoK and axial elongation in anisomyopic children
This retrospective, cohort study was conducted by Zhang & Chen to compare the effect of ortho-k on axial length elongation between the fellow eyes of anisomyopic children. Myopic children were categorised into four groups (n=49 in each group): anisomyopic ortho-k, high-isomyopic ortho-k, low-isomyopic ortho-k and anisomyopic spectacles (control). Axial length was measured at baseline and at 1 and 2-year visits. Axial length elongation and interocular difference in axial length were compared. Ortho-k could reduce the amount of anisomyopia in children primarily through stronger myopia control in the more myopic eye.

Optom Vis Sci 2019;96:1 43-47. Click here for abstract

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