Abstract

Background: Canthal and interpupillary measurements underpin the diagnosis of hypertelorism and telecanthus, the planning of craniofacial reconstruction, the prescribing of spectacles and ocular prostheses, and forensic reconstruction. Population-specific norms are required because these dimensions vary appreciably with ancestry, and their relationship to the wider facial skeleton has been examined less often than the measurements themselves. Methods: Four hundred adults aged 18 to 30 years, comprising 200 of each sex, were measured using digital callipers. The inner, interpupillary, and outer canthal distances were measured, as well as the nasal breadth, face width, facial height, and palpebral fissure length. Canthal and facial indices were derived. Associations were examined by Pearson correlation and multiple linear regression, and agreement between observed and estimated interpupillary distance was assessed by the method of Bland and Altman. Results: Every linear dimension was significantly greater in men, the largest standardised difference affecting facial width. The canthal index showed no sexual dimorphism. Interpupillary distance had the strongest correlation with outer canthal distance and face width, and a regression model that included inner canthal distance and facial width explained two-thirds of its variation. The conventional midpoint estimates underestimated interpupillary distance systematically. Conclusion: Population-specific regression estimation is preferable to the conventional midpoint approximation.

Keywords: Craniofacial anthropometry, Inner canthal distance, Interpupillary distance, Outer canthal distance, Canthal index, Hypertelorism, Telecanthus, Sexual dimorphism