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Normal values and standard deviations for pupil diameter and interpupillary distance in subjects aged 1 month to 19
Colleen MacLachlan1, Howard C Howland
1Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
Insights
This study established normal values for pupil diameter and interpupillary distance (PD) in children up to 19 years old. Findings provide crucial data for clinical and optical applications in pediatric vision development.
Area of Science:
- Ophthalmology
- Developmental Pediatrics
- Optometry
Background:
- Accurate measurement of ocular parameters is essential for understanding visual development.
- Establishing normative data for pupil diameter and interpupillary distance (PD) across pediatric age ranges is critical for clinical diagnosis and optical design.
- Previous studies have provided limited data, necessitating a comprehensive investigation in a large pediatric cohort.
Purpose of the Study:
- To determine normal values for pupil diameter and interpupillary distance (PD) in a large population of subjects from 1 month to 19 years of age.
- To establish age- and sex-specific regression equations for pupil diameter and PD.
- To provide normative data with clinical and industrial applications.
Main Methods:
- Photographic measurement of pupil diameters under mesopic conditions (15.9 ± 0.5 lux).
- Measurement of interpupillary distance (PD) using an interocular distance rule, corrected for viewing distance and systematic errors.
- Statistical analysis including calculation of means, standard deviations, and second-order regression equations for age- and sex-specific data.
Main Results:
- Second-order regression equations were derived for pupil diameter and PD as a function of age for males and females.
- Average male PD (60.94 mm) was significantly wider than average female PD (59.36 mm).
- Pupil diameter and PD increase more gradually than axial length in early childhood.
Conclusions:
- The study provides comprehensive normative data for pupil diameter and PD in children and adolescents.
- These established normal values have significant implications for clinical practice in ophthalmology and optometry.
- The findings are valuable for the optical industry in the development of vision-correcting devices and instruments.
Abstract:
Normal values of pupil diameters and interpupillary distances (PDs) were measured in a population of 1311 subjects (in 4294 visits) ranging from 1 month of age to slightly over 19 years of age. Subjects in this study were recruited from birth announcements in a local newspaper for a developmental vision project. Pupil sizes were measured photographically when the corneas were illuminated by 15.9 +/- 0.5 lux ambient illumination (i.e. under mesopic conditions). Interpupillary distance was measured with an interocular distance rule while the subject fixated an object at 0.66 m distance. These PD measurements were corrected for systematic measurement errors and to an infinite viewing distance using radii of ocular rotation based on age-dependent axial lengths. Means and S.D. were calculated for age, pupil diameter and PD for each 1-year group of male and female subjects. The second order regression equation for average pupil size as a function of age was determined: [males pupil diameter (in mm) = 5.83 +/- 0.181*age in years - 0053*age in years2, r2 = 0.897; female pupil diameter = 5.40 + 0.285*age in years - 0.0109*age in years2, r2 = 0.945]. The dierence between male and female pupil sizes (mean male - female = 0.13 mm) was marginally not significant (p < 0.054). The average corrected PDs as a function of age were found to approximate another second-order regression equation: (males PD = 43.36 + 1.663*age in years - 0.034*age in years2, r2 = 0.986; females PD = 41.76 + 1.891 *age in years - 0.052*age in years2, r2 = 0.986). Male PD was wider than female PD by an average of 1.58 mm (p < 0.0003). As expected, the results of this study were similar to a preliminary investigation conducted by Thunyalukul et al. [Invest. Ophthalmol. Vis. Sci. 37 (1996) S731] on a portion of the present data set, and also very similar to data from another study of comparable racial composition using a different measurement method [Pryor, Pediatrics 44 (1969) 973]. It was concluded that pupil diameter and PD increase more gradually than axial length of the eye in the first few years of life. The normal values and S.D. for both pupil size and PD determined in this study have important clinical implications as well as applications in the optical industry.