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Clinical science
Lens power in Iranian schoolchildren: a population-based study
  1. Hassan Hashemi1,
  2. Reza Pakzad1,
  3. Rafael Iribarren2,
  4. Mehdi Khabazkhoob3,4,
  5. Mohammad Hassan Emamian5,
  6. Akbar Fotouhi6
  1. 1 Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
  2. 2 Department of Pathology, Laboratory of Ocular Investigations, School of Medicine, University of Buenos Aires, Argentina
  3. 3 Department of Medical Surgical Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran
  4. 4 Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
  5. 5 Ophthalmic Epidemiology Research Center, Shahroud University of Medical Sciences, Shahroud, Iran
  6. 6 Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
  1. Correspondence to Dr Mohammad Hassan Emamian, 7 Tir SQ, Shahroud University of Medical Sciences, Shahroud, Iran; emamian{at}shmu.ac.ir, pishgiri{at}yahoo.com

Abstract

Aims To evaluate lens power (LP) in schoolchildren aged 6–12 years.

Methods This cross-sectional study was conducted in Shahroud, northeast Iran. The students were selected through random cluster sampling and underwent the measurements of biometry, uncorrected and corrected visual acuity, non-cycloplegic and cycloplegic refraction. The LP was calculated using the Bennett formula.

Results Of 6624 invited children, 5620 (84.8%) participated in the study and data of 4870 children were finally analysed. The mean age of the participants was 9.7 years and 2277 participants (46.02%) were girls. The mean LPs were 22.86 dioptres (D) in total study population, 23.91 D in 6 and 22.10 D in 12-year-old children. The mean LP was higher in girls than boys (23.48 D vs 22.34 D), in rural children than urban children (23.17 D vs 22.83 D) and in children with hyperopia (23.25 D) than children with myopia or emmetropia (22.64 D and 22.86 D, respectively). In the multiple linear regression model, lens thickness (β=1.59, p<0.001), anterior chamber depth (β=2.21, p<0.001) and female sex (β=0.016, p=0.015) were associated with an increase in the LP, while axial length (AL) (β=−4.41, p<0.001), corneal power (CP) (β=−1.47, p<0.001), spherical equivalent (SE) (β=−1.50, p<0.001) and age (β=−0.005, p=0.001) were associated with a decrease in the LP. AL and sex had the highest and lowest impact on LP, respectively.

Conclusion LP decreased with age between 6 and 12 years and was associated with a shorter AL, deeper ACD, higher SE, thicker lens and lower CP.

  • lens power
  • ocular components
  • children
  • ocular biometry
  • iran

https://doi.org/10.1136/bjophthalmol-2017-310565

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    Footnotes

    • Contributors HH and RP drafted the manuscript, contributed to the preparation of the study protocol, conceptualised and conducted all statistical analyses and were the primary authors of this article. RI and MK contributed to the conceptualisation of the paper and the statistical analyses and critically revised the manuscript. MHE and AF conceived and designed the study, contributed to the preparation of the study protocol, contributed to the conceptualisation of the paper and the statistical analyses and critically revised the manuscript.

    • Funding This work was supported by the Noor Ophthalmology Research Center and Shahroud University of Medical Sciences, Grant Number 9329.

    • Competing interests The authors report no conflicts of interest and have no proprietary interest in any of the materials mentioned in this article.

    • Ethics approval The ethics committee of Shahroud University of Medical Sciences, Shahroud, Iran.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement Any new paper about Shahroud School Children Eye Cohort Study is welcome. The researchers can contact Dr Mohammad Hassan Emamian by emamian@shmu.ac.ir.

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