Objective: To provide a normal comparison group against which to judge symmetry results after cleft surgery and to introduce the thin lip correction (TLC) feature in SymNose. A lip-aspect ratio algorithm has been added to the latest version of SymNose to compensate for the higher degree of overlap in thicker lips when compared to thin lips.
Design: Retrospective analysis of symmetry in healthy participants, using the computer-based program SymNose on both anteroposterior (AP) and base view images. Photographs of 91 noncleft children were traced twice by 3 independent investigators experienced with SymNose.
Participants: Five-year-old healthy participants from a local state school in Tavistock (West Devon, United Kingdom).
Main outcome measure: Asymmetry expressed as the perimeter mismatch percentage for nose and lip features on AP view images and for nose features on base view images.
Results: The perimeter mismatch reference range for the nose (AP view) was 2.65% to 30.91%, for the lip 2.13% to 15.44%, for the nose (base view) 1.69% to 14.84%, for the nostrils 4.68% to 26.6%, and for the width-height ratio 1.15% to 1.80%. The perimeter mismatch percentage for the lip without TLC was significantly higher compared to the perimeter mismatch percentage with TLC (P < .001).
Conclusion: This article provides a noncleft reference range for all perimeters drawn from SymNose against which to compare results after cleft surgery at 5 years of age. Furthermore, it shows the importance of correcting for variance in lip volume per child.
Keywords: SymNose; cleft lip; normal controls; thin lip compensation.