Young adults wearing the spectacle-mounted Clouclip device to measure viewing behaviour and light exposure also kept an activity diary. Mean daily near work and outdoor time were subjectively reported at about 150% of the objectively measured hours. This indicates the value of objective measures in research, as well as for clinical education and behaviour modification tools in future.
Light-emitting glasses worn by young adults for 1-2 hours reduced axial length and increased choroidal thickness by around 20 microns compared to darkness. The study participants viewed a colour-muted television at 5m while indoors, and the changes regressed within 30 minutes. A future myopia treatment to increase ‘outdoor’ time?
This study measured central and relative peripheral refraction (RPR) in children aged 6-7 years and 12-13 years at baseline and again one year later. There was no correlation found between central and peripheral refraction in the younger group. In the older group, more hyperopic temporal RPR was correlated with a myopic shift, but only explained 10% of the variance in refraction after 12 months.
It’s known that emmetropizing children undergo axial eye growth of around 0.1mm per year. Is this amount of growth in myopes also ‘physiologic’? In this study, data from six myopia control clinical trials was analyzed to find the axial growth component which did not result in a change in refraction. For myopes, this ‘physiologic’ growth appears to be less than 0.1mm per year, which has implications for judging progression and treatment success.
A country-wide intervention to increase outdoor time in 5-6 year olds resulted in the prevalence of myopia decreasing from 15% in the 2014 cohort (before the intervention) to 8% in 2016 cohort (exposed to the intervention for up to two years) and was stable for three years thereafter. Increasing outdoor time works!
This study reported that children wearing DIMS spectacle lenses showed increased sub-foveal choroidal thickness than controls at 1 week which increased in the first 6 months and was maintained at 2 years. There was a correlation between more choroidal thickening and less axial elongation, but choroidal thickening only explained around 8% of the variation in axial length.
The BLINK study found that +2.50 Add centre-distance multifocal contact lenses (MFCLs) slowed myopia progression but the +1.50 Add didn’t. Further analysis indicates that increased peripheral defocus created by the +2.50 Add only accounted for around 15% of the myopia control effect, indicating other mechanisms are involved.
There is general widespread accepted belief that increasing time spent outdoors can be protective against progression of myopia. Xiong et al set out to better understand the research by performing a meta-analysis of 51 clinical trials and longitudinal studies that investigated the relationship between time spent outdoors and the risk of either developing myopia, progression of existing myopia or a myopic shift in refractive error.
Soft contact lenses designed to simulate the change in refraction optical pro-file from orthokeratology (OK) fail to slow axial eye elongation or change to refrac-tion over 1-year of wear in children, leading to suggestion that OK’s propensity to slow myopia progression may not be due to changes OK makes to optical profile.