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Strabismus. 2016 Sep;24(3):113-9. doi: 10.1080/09273972.2016.1205103. Epub 2016 Aug 2.

Strabismus and Near Point of Convergence and Amblyopia in 4-6 Year-Old Children.

Author information

1
a Department of Optometry, School of Paramedical Sciences , Mashhad University of Medical Sciences , Mashhad , Iran.
2
b Noor Research Center for Ophthalmic Epidemiology , Noor Eye Hospital , Tehran , Iran.
3
c Noor Ophthalmology Research Center , Noor Eye Hospital , Tehran , Iran.
4
d Refractive Errors Research Center, School of Paramedical Sciences , Mashhad University of Medical Sciences , Mashhad , Iran.
5
e Department of Medical Surgical Nursing, School of Nursing and Midwifery , Shahid Beheshti University of Medical Sciences , Tehran , Iran.

Abstract

PURPOSE:

To determine the prevalence of strabismus and amblyopia, and the distribution of the near point of convergence (NPC), in a population of children aged 4 to 6 years.

METHODS:

In this cross-sectional study, preschoolers in Mashhad were sampled using a random multistage cluster sampling approach. Examinations were done after obtaining parental consent. All participants had measurements of uncorrected visual acuity, corrected visual acuity, and non-cycloplegic refraction, and they had near and far cover tests to determine tropia and phoria.

RESULTS:

Of the 3765 selected children, 3701 participated in the study. The prevalence of tropia was 1.21% (95% confidence interval [CI]: 0.86-1.57). Near and near/far tropia was observed in 0.83% (95% CI: 0.53-1.12) and 0.39% (95% CI: 0.18-0.59), respectively. Tropia was significantly more prevalent in boys (P=0.005). The most common type of tropia was esotropia, 0.22% (95% CI: 0.07-0.37). Among participants, 63.92% (95% CI: 62.36-65.48) had phoria; prevalence of far, near, and near/far phoria was 0.22% (95% CI: 0.07-0.37), 60.47% (95% CI: 58.88-62.07), and 3.22% (95% CI: 2.65-3.8), respectively. Mean NPC was 5.1 cm (95% CI: 5.05-5.14). NPC increased by 0.08 cm per month of age (P=0.033) and was 0.10 cm higher in boys compared to girls (P=0.027). Based on NPC, 61.58% (95% CI: 59.99-63.17) were symptomatic. The prevalence of amblyopia was 0.41% (95% CI: 0.20-0.61). The type of amblyopia was anisometropic, strabismic, and isoametropic in 75%, 11.1%, and 8.5%, respectively.

CONCLUSION:

The prevalence of amblyopia in this study population was not high; however, the prevalence of tropia was average compared to previous studies in Iran. Describing NPC in a 4- to 6-year-old Iranian population for the first time, we found that NPC increased with age in this sample.

KEYWORDS:

Amblyopia; near point of convergence; preschool children; strabismus

PMID:
27485705
DOI:
10.1080/09273972.2016.1205103
[Indexed for MEDLINE]

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