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Canthal tilt: read the angle, not a verdict.

Canthal tilt describes the slope between the inner and outer corners of an eye. The sign tells you which corner is higher, not whether a person looks good.

By TrueMax · Updated 20 September 2026 · Product explanation, not clinical advice

The inner corner, or medial canthus, is near the nose. The outer corner, or lateral canthus, is toward the temple. A canthal-tilt measurement compares the line between them with a horizontal reference. Clinical photographic research also distinguishes the eye-corner line from its baseline. See a photographic measurement method.

Eye-corner line and horizontal baseline A schematic eye with the inner corner on the left and outer corner slightly higher on the right. A teal line joins them. A dashed horizontal baseline starts at the inner corner. The angle is positive because the outer corner is higher. Outer corner · temple sideInner corner · nose sidehorizontal baselinepositive tilt BAH
A
Inner eye corner, nearest the nose.
B
Outer eye corner, nearest the temple.
H
Dashed horizontal baseline. The teal A-to-B line slopes up in this positive-tilt example.
Original schematic. The tilt is deliberately exaggerated for legibility and is not an ideal value. The marked corners are not the eyebrow ends, iris edges or ends of an eyeliner wing.

Positive, neutral and negative describe direction

These are geometric descriptions. They do not diagnose an eye condition or establish an ideal for every face. A rounded display of 0.0 degrees also does not prove that the two corners are exactly level.

How TrueMax calculates it

TrueMax measures the inner-to-outer corner line for each eye in image space, corrects each for estimated sideways image roll, then reports their average. The separate canthal-tilt asymmetry reading is the absolute difference between the two corrected angles.

A simple illustration: if an outer corner is 5 image units above the inner corner over a horizontal span of 50 units, the angle is arctan(5 ÷ 50) ≈ 5.7°. That example explains the calculation, not a target. If the corrected left and right readings were 4° and 6°, the displayed average would be 5° and their difference 2°.

Head roll and head pitch are not the same problem

Roll means tilting your head toward one shoulder. It changes the eye lines relative to the image horizontal. TrueMax estimates a correction, but that correction still depends on its landmarks.

Pitch means looking up or down. Correcting sideways roll does not make an up- or down-tilted photo equivalent to a straight-on one. A study using standardized photos of 12 volunteers found that changing head pitch changed the apparent eye-area measurements, including canthal tilt. This is evidence for consistent capture, not a validation of TrueMax. Read the head-tilt study.

Check the image before treating a difference as change

  1. Use a straight-on photo with a level head, open eyes and a relaxed expression.
  2. Check that the marks sit at the actual inner and outer eye corners, not on nearby lashes, makeup or brow points.
  3. Compare the two individual eye readings as well as their average. An average can hide a difference between sides.
  4. Repeat with the same setup if the result surprises you. A small difference between photographs is not enough to establish anatomical change.

Reference fit is not attractiveness

The model's preferred direction or threshold is a scoring choice, not proof that increasing the angle would improve your appearance. A scan cannot tell you that a procedure is needed, and one eye measurement cannot describe the whole eye area.

Start with a well-framed front photo

Follow the capture guide. For the bigger picture, read what a face score means and how TrueMax uses references.

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