The ONO angle (Outer canthus, Nasal, Outer canthus) is the angle subtended by 2 lines connecting the base of the nose to each outer canthus. It provides an estimate of spacing between the eyes and the upper facial height.
Patient selection: Data is available for children from 5 to 11 years of age
Technique:
(1) The child may either be sitting erect with the eyes pointing forward, or lying face up with eyes pointing vertically.
(2) The angle can be measured from a photograph of the child in the proper position.
|
age |
+2 SD |
+1 SD |
mean |
-1 SD |
-2 SD |
|
5 |
105 |
100 |
95 |
89.5 |
84 |
|
6 |
104.7 |
99.7 |
94.5 |
89 |
83.6 |
|
7 |
104.2 |
99.1 |
93.8 |
88.4 |
83 |
|
8 |
103.6 |
98.3 |
92.9 |
87.6 |
82.3 |
|
9 |
102.8 |
97.5 |
92 |
86.8 |
81.4 |
|
10 |
101.9 |
96.4 |
91.1 |
85.7 |
80.4 |
|
11 |
100.9 |
95.5 |
90.4 |
84.8 |
79.5 |
from Figure 7.91 based on the data of M Patton from 1987
This data can be approximated by second order equations derived in JMP.
+2 SD line=
= (-0.07024 * ((age in years)^2)) + (0.434524 * (age in years)) + 104.6
+1 SD line=
= (-0.065476 * ((age in years)^2)) + (0.27262 * (age in years)) + 100.34286
mean line=
= (-0.02381 * ((age in years)^2)) - (0.419048* (age in years)) + 97.785714
-1 SD line=
= (-0.053571 * ((age in years)^2)) + (0.0607143 * (age in years)) + 90.557143
-2 SD line=
= (-0.058333 * ((age in years)^2)) + (0.1654762 * (age in years)) + 84.671429
Interpretation - The angle may be abnormal in a child with:
(1) hypotelorism (decreased angle)
(2) hypertelorism (increased angle)
(3) reduced upper facial height (increased angle)
(4) increased upper facial height (decreased angle)
