Correlation between Interpupillary and Inner-Outer Intercanthal Distances in Individuals Younger than 20

Purpose: to determine the correlation between interpupillary distance (ipd) and innerouterintercanthal distance (ioicd) and to find a regression equation for calculating ipdbased on ioicd measurements.methods: the study subjects were randomly selected from individuals aged 3 monthsto 20 years who were referred to our ophthalmology clinic, health care centers and childrenattending kindergartens. participants were divided into 4 age categories: .3, 3-5,5-12.5 and 12.5-20 years. ipd was measured by a pd meter (pd2, oculus, germany);other parameters including ioicd, nasal limbus to temporal limbus (nltl), innerintercanthal distance (iicd) and outer intercanthal distance (oicd) were measuredusing a translucent plastic ruler.results: the study included 254 female (60.6%) and 165 male (39.4%) subjects withmean age of 87.7}73.2 (range 3-240) months. significant correlation was observedbetween ioicd and ipd in the 3-5 yr and 12.5-20 yr age groups. in the .3 and 5-12.5year age groups, nltl had the best correlation with ipd. the regression equationsfor calculating ipd according to ioicd were as follows. in male subjects, nearipd= 0.941×ioicd (r2= 0.98, p<0.001) and for female subjects, near ipd= 0.948×ioicd(r^2= 0.98, p<0.001).conclusion: ipd and ioicd measurements are strongly and positively correlated;ioicd measurements are simpler to obtain and may be used to calculate ipd readingswhich are more difficult to measure by usual methods in children.