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

This month we begin with an editorial in the BCLA journal Contact Lens & Anterior Eye by FIACLE Dr Fabrizio Zeri and IACLE President Dr Shehzad Naroo on measures to adopt in contact lens practice in light of the COVID-19 outbreak.

Getting back to our quest to understand myopia control strategies better, we begin the issue with a systematic review of various interventions to slow myopia. Another review throws light on the much-debated topic of un-, under- and over-correction of myopia. Full text is available for both these reviews. The rising myopic epidemic has also evoked interest in measuring peripheral eye length, a topic we cover this month.

An Australian group studies the zone of clear single binocular vision in orthokeratology. Another study discusses the optical performance of multifocal contact lenses in terms of light distortion and its relationship to pupil size and shape.

A team from China attempts to answer the relevant question in growing cities: does air quality influence the selection tendency of lens wearers? Access the full text to read the results of this interesting study. And finally, we include a paper by Iranian researchers on the effects of corrective contact lenses on corneal microstructure.

The IACLE Education Team

Journals reviewed in this issue:

Cochrane Library  Home

Clinical and Experimental Optometry  103:2 

Eye & Contact Lens  46:2  

Contact Lens & Anterior Eye  43:2, In Press

Contact lens practice in the time of COVID-19

Zeri & Naroo’s editorial outlines the current situation on the coronavirus disease outbreak and actions to be taken in contact lens practice based on available evidence. Measures include rescheduling non-urgent appointments, use of personal protection equipment and disinfection of contact lens equipment and trial sets. Hand sanitisation is emphasized, along with the importance of practitioner and staff monitoring.

Cont Lens Anterior Eye 2020. DOI: 10.1016/j.clae.2020.03.007. Read the full text

Interventions to slow myopia in children

To assess the effects of interventions in slowing myopia progression in children, Walline et al conducted this systematic review including 41 randomised controlled trials with 6,772 participants. Anti-muscarinic topical medication was effective in slowing myopia progression in children. Multifocal lenses, either spectacles or contact lenses, may offer a small benefit. Orthokeratology contact lenses, although not intended to modify refractive error, were more effective than single-vision lenses in slowing axial elongation.

Cochrane Database Syst Rev 2020;Jan 13. CD004916.pub4. DOI: 10.1002/14651858. Read the full text

Role of correction in myopia progression

This systematic review by Logan & Wolffsohn investigated the association between un-, under- and over-correction of myopic refractive error and myopia progression in children and adolescents (up to 18 years of age). Ten studies were included in quantitative synthesis. The overall findings are equivocal, with under-correction causing a faster rate of myopia progression. There is no strong evidence of benefits from un-correction, monovision or over-correction. Hence, current clinical advice advocates the full correction of myopia.

Clin Exp Optom 2020;103:2 133-137. Read the full text

Peripheral ocular length measurement

Koumbo Mekountchou et al summarize instruments used for peripheral eye length (EL) measurement, the similarity of the techniques, and their advantages and disadvantages. They also suggest features and specifications for an ‘ideal’ instrument. Reviewed are: ulrasonography, partial coherence Interferometry, Laser Doppler interferometry, optical low coherence reflectometry and optical coherence tomography. While significant advancements have been made, methods and instruments are still in the research and prototype stage.

Clin Exp Optom 2020;103:2 138-147. Read the abstract

Myopic orthoK and clear single binocular vision

Gifford et al evaluated the zone of clear single binocular vision (ZCSBV) in 12 myopic children (8-16 years) and eight young adults (18-29 years) after 12 months of orthokeratology (OK) wear. Assessments were performed when myopia was corrected with single-vision soft lenses, and again after 1m and 12m of OK wear. ZCSBV expands towards a more divergent, improved accommodation response in OK wear, without loss of convergence or relaxation of accommodation. Findings may indicate a mechanism for OK’s efficacy for myopia control.

Eye & Contact Lens 2020;46:2 82-90. Read the abstract

Light distortion with multifocal contact lenses

Monsálvez-Romín et al recruited seven subjects (14 eyes) to study the light distortion effects of soft multifocal contact lenses and the influence of different pupil size and shape. A Light Disturbance Analyser device was employed for light characterization. Metrics such as the light distortion index, best-fit circle radius and its irregularity were analysed. Pupil sizes used were 3mm and 5mm. The multifocal contact lenses increased light distortion effects under low light conditions, especially with larger pupils.

Cont Lens Anterior Eye 2020;43:2 130-136. Read the full text

Air quality and selection tendency of lens wearers

To investigate whether air quality influences ocular comfort when wearing contact lenses and selection tendency of lens wearers, Zhao et al administered a questionnaire to 120 (112 analyzed) myopic wearers. This study did not find statistically significant differences in ocular comfort while wearing contact lenses and in the eye scores of contact lens wearers under different air quality conditions. Air quality did affect the selection of correction among some contact lens wearers. Studies under moderate to severe pollution conditions are needed.

Cont Lens Anterior Eye 2019;Nov 22. DOI: 10.1016/j.clae.2019.11.011. Read the full text 

Effects of contact lenses on corneal microstructure

To determine the effect of wearing corrective contact lenses on the corneal microstructure, Alipour et al used confocal microscopy to conduct this prospective cohort study of 33 neophyte subjects wearing soft toric silicone hydrogels (8 cases), RGPs (17 cases) and mini-sclerals (8 cases). No significant changes in sub-basal nerve and keratocyte densities were seen after 6 months’ wear in all groups. Soft toric silicone hydrogel lenses had the least impact on the corneal cellular microstructure.

Eye & Contact Lens 2020;46:2 74-81. Read the abstract

© International Association of Contact Lens Educators 2020

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