Ophthalmology
Volume 115, Issue 4 , Pages 686-692, April 2008

Season of Birth, Natural Light, and Myopia

  • Yossi Mandel, MD, MHA

      Affiliations

    • Israel Defense Force Medical Corps, Ramat-Gan, Israel.
    • Selim and Rachel Benin School of Computer Science and Engineering, Hebrew University of Jerusalem, Jerusalem, Israel.
    • Corresponding Author InformationCorrespondence to Yossi Mandel, MD, MHA, Selim and Rachel Benin School of Computer Science and Engineering, Hebrew University of Jerusalem, Jerusalem, Israel.
    • ,
  • Itamar Grotto, MD, MPH

      Affiliations

    • Israel Defense Force Medical Corps, Ramat-Gan, Israel.
    • Department of Epidemiology, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
    • ,
  • Ran El-Yaniv, PhD

      Affiliations

    • Technion—Israel Institute of Technology, Haifa, Israel.
    • ,
  • Michael Belkin, MD, MA

      Affiliations

    • Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Sheba Medical Centre, Tel Hashomer, Israel.
    • ,
  • Eran Israeli, MD, MHA

      Affiliations

    • Israel Defense Force Medical Corps, Ramat-Gan, Israel.
    • Department of Medicine, Hebrew University–Hadassah Medical Center, Jerusalem, Israel.
    • ,
  • Uri Polat, PhD

      Affiliations

    • Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Sheba Medical Centre, Tel Hashomer, Israel.
    • ,
  • Elisha Bartov, MD

      Affiliations

    • Edith Wolfson Medical Center, Holon, Israel.

Received 15 November 2006; received in revised form 21 May 2007; accepted 21 May 2007. published online 15 August 2007.

Available online: August 15, 2007.

Purpose

To investigate the possible roles of season of birth and perinatal duration of daylight hours (photoperiod) in the development of myopia.

Design

Retrospective, population-based, epidemiological study.

Participants

A total of 276 911 adolescents (157 663 male, 119 248 female) 16 to 22 years old. All were Israeli-born conscripts to the Israeli Defense Forces who were examined during the 5-year period 2000 through 2004.

Methods

Noncycloplegic refraction was determined by autorefractometer and validated by qualified optometrists. Myopia, defined on the basis of right eye spherical equivalence, was classified as mild (−0.75 to −2.99 diopters [D]), moderate (−3.0 to −5.99 D), or severe (−6.0 D or worse). The photoperiod was recorded from astronomical tables and classified into 4 categories. Using multivariate logistic regression models, we calculated odds ratios (ORs) for several risk factors of myopia including season of birth.

Main Outcome Measure

The OR for photoperiod categories as risk factors for myopia.

Results

Overall prevalences of mild, moderate, and severe myopia were 18.8%, 8.7%, and 2.4%, respectively. There were seasonal variations in moderate and severe myopia according to birth month, with prevalence highest for June/July births and lowest for December/January. On multivariate logistic regression, the ORs of photoperiod categories for moderate and severe myopia were highly significant and demonstrated a dose–response pattern. Odds ratios for severe myopia were highest for the shortest versus the longest photoperiods (1.24; 95% confidence interval, 1.15–1.33; P<0.001). Mild myopia was not associated with season of birth or perinatal light exposure. Other risk factors were gender (1.14 for female), education level (1.32 for age above 12), and father’s origin (1.31 for Eastern vs. Israeli origin).

Conclusion

Myopia in this population is associated with birth during summer months. The exact associating mechanism is not known but might be related to exposure to natural light during the early perinatal period.

 

 Manuscript no. 2006-1321.

 The authors have no competing interests.

PII: S0161-6420(07)00597-0

doi:10.1016/j.ophtha.2007.05.040

Ophthalmology
Volume 115, Issue 4 , Pages 686-692, April 2008

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