To determine the distribution of near point of convergence (NPC) and its related factors in 6 to 12-year old children.

In a cross-sectional study in 2015, the urban and rural children of Shahroud , north of Iran, were sampled. All rural schoolchildren were invited to the study, and in the urban area, we conducted random cluster sampling. Examinations included measurement of uncorrected and corrected visual acuity, manifest, cycloplegic, and subjective refraction, and the cover test. NPC was measured with the best optical correction.

Of the 6624 sampled schoolchildren, 5620 participated in the study, and after applying the exclusion criteria, the final analysis was conducted on data from 5458 students; their mean age was 9.24 ±1.71 years (6 to 12 years) and 53.6% (n=2927) of them were male. Mean NPC was 8.07cm [95% confidence interval (CI): 7.96-8.19]; 8.07cm (95% CI: 7.92-8.22) in boys and 8.08cm (95% CI: 7.91-8.25) in girls (p=0.914). NPC significantly increased with age (p<0.001). Mean NPC in emmetropic, myopic, and hyperopic students were 8.12, 7.05, and 8.17cm, respectively (p<0.001). The multiple linear regression model revealed significant correlations for NPC with age (coefficient=0.11, 95% CI: 0.06-0.16, p<0.001), spherical equivalent (coefficient=-0.13, 95% CI: 0.06-0.20, p<0.001) and the amplitude of accommodation (coefficient=-0.35, 95% CI: -0.38—0.33, p<0.001).

Mean NPC in 6-12-year-old Iranian children was 8.07cm, which is higher than values reported in previous studies. Mean NPC showed a slight increase with age. Myopic schoolchildren had the lowest and hyperopics had the highest NPC. Higher degrees of accommodation amplitude were associated with increased NPC.