Intercanthal distance : palpebral fissure length
The distance between the inner corners of the eyes, expressed as a multiple of the average eye length (inner to outer corner).
How to read it
the eyes are set closer together than the reference mean relative to their length. This is a descriptive statement about proportion, not a defect; wide-set and close-set eyes are both common in every population studied.
the spacing between the eyes is close to the reference mean for eye length. This is the region most robustly measurable from a frontal photograph, since both distances lie in the same depth plane.
the eyes are set wider apart than the reference mean relative to their length. In East Asian reference groups a wider ratio is itself the population norm (Jayaratne 2012 found 100% of a Southern Chinese sample exceeded the neoclassical canon).
The canon holds in ~41% of the White North Americans it was derived from, 0% of Southern Chinese, and 25–29% of Saudi adults. Deviation is the norm, not a flaw.
Conformity in published samples: na white 41% · east asian 0% · middle east m 29% · middle east f 25%
Reference values by population
| Reference population | Female (mean ± SD) | Male (mean ± SD) | n | Source |
|---|---|---|---|---|
| North American White | 1.036 ± 0.09 | 1.064 ± 0.102 | 2326 | Farkas 1994/2005 (NA White young adults) prov. |
| East Asian | 1.268 ± 0.112 | 1.281 ± 0.111 | 618 | Farkas 2005 (Chinese/Japanese/Vietnamese/Thai pooled); Jayaratne 2012 (Southern Chinese, n=103) prov. |
| South Asian | 1.068 ± 0.098 | 1.083 ± 0.104 | 210 | Farkas 2005 (Indian); Metgudmath 2022 prov. |
| African / African diaspora | 1.081 ± 0.101 | 1.095 ± 0.107 | 300 | Farkas 2005 (African-American, Zulu, Angolan) prov. |
| Middle Eastern | 1.033 ± 0.095 | 1.066 ± 0.102 | 348 | Farkas 2005 (Turkish, Iranian, Egyptian); Al-Sebaei 2015 (Saudi, n=168) prov. |
| Hispanic / Latino | 1.085 ± 0.101 | 1.1 ± 0.107 | 120 | Farkas 2005 (Mexican-American) prov. |
| Not specified — show pooled | 1.093 ± 0.117 | 1.113 ± 0.121 | 3922 | Unweighted pool of the six groups above prov. |
Where these numbers come from
Transcribed from the cited anthropometric literature; SDs of ratios are propagated conservatively (independence assumed). Entries marked prov. await line-by-line audit against the primary tables — see the norm provenance note.
Why every value has an error bar
Every value Canthion reports carries a 1σ uncertainty propagated from MediaPipe Face Mesh's published accuracy (3.96% of inter-ocular distance mean absolute error per landmark, Kartynnik 2019). For a typical 300 px inter-pupil photo that is ≈12 px per landmark, which is why small ratios and angles get wide intervals. A number without an interval is a number pretending to be more precise than it is.
References
- Farkas, Hreczko, Kolar & Munro (1985). Vertical and horizontal proportions of the face in young adult North American Caucasians: revision of neoclassical canons. Plast Reconstr Surg 75(3):328–338. pubmed.ncbi.nlm.nih.gov/3883374/
- Farkas, Katic & Forrest (2005). International Anthropometric Study of Facial Morphology in Various Ethnic Groups/Races. J Craniofac Surg 16(4):615–646. doi.org/10.1097/01.SCS.0000171847.58031.9E
- Jayaratne, Deutsch, McGrath & Zwahlen (2012). Are Neoclassical Canons Valid for Southern Chinese Faces? PLoS ONE 7(12):e52593. doi.org/10.1371/journal.pone.0052593
- Al-Sebaei (2015). The validity of three neo-classical facial canons in young adults originating from the Arabian Peninsula. Head Face Med 11:4. doi.org/10.1186/s13005-015-0064-y
Related: how bone-level measurements are taken from a photo · methodology · all insights