Myopia and natural lighting extremes: risk factors in Finnish army conscripts

Abstract

ABSTRACT.Purpose: To establish whether features of environmental lighting in far northern latitudes might be associated with prevalence of myopia. Methods: Using both questionnaires and military medical examinations, this cross-sectional survey of Finnish conscripts assessed both light exposure and conventional risk factors for myopia. Results: While myopia was not associated with the month of birth, there was a trend towards a higher prevalence of myopia among conscripts living above the Arctic Circle, consistent with the hypothesis that ambient lighting might influence refractive development. Other novel associations with myopia were decreased sunglasses use and brown iris colour. As indicated by other reports, myopia was found to be associated with family history, education and nearwork. Conclusion: Although constraints inherent in surveying this military population may have limited our ability to detect associations, the positive findings suggest that studying northern populations may prove useful in clarifying any potential role of the light/dark cycle in refractive development.

Association between parental myopia and the risk of myopia in a child

“…Following this review, a number of manuscripts were excluded due to information, including outcome, the exposure of interest or essential data, being omitted. A total of 16 studies were eligible for final inclusion (12)(13)(14)(15)(16)(17)(26)(27)(28)(29)(30)(31)(32)(33)(34). Of these, six were prospective cohort (12,13,15,17,31,32), eight were cross-sectional (14,16,(26)(27)(28)(29)(30)35) and two were case-control studies (33,34).…”

“…The present meta-analysis included 16 studies with 8,393 cases of myopia. The selected studies were from four continents (seven from Asia (14,16,26,28,32,34,35), four from Europe (17,29,31,33), three from the United States (12,13,30) and two from Australia (15,27). All of the studies recruited male and female participants aged ≤31 years.…”

“…Three of the studies reported the participants' myopia as a SER ≤-0.75 D in the horizontal and vertical meridians following cycloplegic autorefraction (12,13,30). The participants' myopia in another four studies was identified as SER ≤-1.5 D (17), a visual acuity ≥6/9 following correction with a concave lens >0.5 D (34), a SER between -0.75 and -2.99 D (31), and self-reported wearing of 'minus' glasses (29).…”

Myopia, Light and Circadian Rhythms

“…Seasonal variations in photoperiod are particularly extreme above the Arctic Circle. However, in a study of Finnish military conscripts (Vannas, Ying et al 2003) no associations between myopia prevalence and birth month, global irradiance at birth month or daily hours of darkness during the birth month were found, although there was a trend towards higher prevalence of myopia among conscripts living above the Arctic Circle.…”

Vitamin D in Dry Eye and Myopia

“…A multiple-site study in the U.S. reported that myopic children spent fewer hours outdoors (by 1.1 to 1.8 hours) as compared to emmetropic children before and after the onset of myopia (Jones-Jordan et al, 2011), suggesting that long period spent indoors plays an important role in myopia development. Some studies have suggested an association between light and myopia (Chapell et al, 2001;Czepita et al, 2003;Saw et al, 2002;Vannas et al, 2003), more importantly and recently, it has been demonstrated that myopes exposed to shorter sunlight hours (by 2.5 hours to 2.8 hours) as compared to non-myopes in the week in the young children (Dharani et al, 2012), though there was some degree of disagreement between different measure methods for sunlight exposure hours. However, other studies in earlier years did not report this association (Guggenheim et al, 2003;Saw et al, 2002;Zadnik et al, 2000).…”