Canthal Tilt: How You Measure Eye Corner Inclination

Canthal tilt is the slant of the line from your inner eye corner to your outer eye corner. Outer corner higher: positive. Corners level: neutral. Outer corner lower: negative. Sounds simple. Brow position, head roll, eyelid tension, expression, and where you mark the corners all move the number. Tilt is one part of eye shape. It is not a beauty score. It is not a diagnosis of orbital support.

Mark endocanthion and exocanthion on one eye. Draw the line between them. Compare it with a true horizontal in a level frontal image. Repeat on the other eye. Do not assume the two sides match.

Some papers measure the whole fissure axis. Others split medial and lateral lid segments. Related, not the same contour. Say which method you used before you compare numbers.

A positive number means the outer corner is higher. Magnitude depends on the coordinate system. Keep the head level.

Medial and lateral canthal tendons hold the eyelids. Orbital shape, globe position, lid tension, lower lid support, soft tissue, and the lid margins all change the angle you see.

Canthal tilt does not tell you where the whole bony orbit sits. You are measuring soft tissue across the eyelid opening. The same angle can show up with different lid shapes and different orbits.

A three dimensional study from ages 4 to 73 found fissure inclination changing with age, and the age pattern differed by sex (PMID 19153019). A later three dimensional study found age and sex related shifts in endocanthion and exocanthion position (PMID 35969325).

In a Korean sample, average fissure slant was 7.9 degrees in adult men and 8.8 degrees in adult women (PMID 18349663). A Malaysian South Indian sample reported 4.72 degrees in men and 7.04 degrees in women (PMID 23112966). Different samples and methods, different norms. Do not mix them.

A forced choice experiment found edited female faces with accentuated medial canthal tilt preferred over the unmodified versions (PMID 17237692). That is one image manipulation study. It is not proof that more tilt always helps every face.

Three dimensional comparison of attractive and general Italian young adults found greater eye fissure inclination in the attractive group, plus longer fissures and different orbital measurements (PMID 24857159). That is a feature pattern in one population.

Tilt sits with aperture, eye length, brow position, lower lid contour, sex cues, and face shape. Past a balanced range, more tilt can look strained or surgically altered.

Roll rotates the whole face and adds the same directional error to both eyes. Yaw changes apparent lengths and can shift the visible corner. Pitch changes lid show and brow relation. Use a level frontal image, direct gaze, neutral eyelids.

Check the line through both pupils and the face axes before you trust the number. Makeup, lashes, shadow, and a hidden medial corner can move the endpoints you think you marked.

Solar estimates left and right corner inclination after pose normalization. You get the average, the side difference, image quality, eye aperture, fissure length, intercanthal distance, and brow relation together.

Solar uses a balanced distribution. More is not always better. A clear deviation can move the eye region score. No single angle decides the full facial ranking.

Canthal tilt tells you how the eye corners sit. Measure both eyes on a level, neutral portrait or the number is junk.

Use a matching population reference. Read the angle with the rest of the orbital region. It is not a stand-alone beauty switch.

Read it against the rest of the measurements series. Trait context: what facial dimorphism is.

Want this measurement read across your own facial structure? Run the Solar facial analysis.