Free canthal tilt test

The medial canthus is the inner eye corner and the lateral canthus is the outer corner. When the outer corner sits higher, the line has a positive tilt; when it sits lower, the tilt is negative; a nearly level line is commonly described as neutral.[1]

Clinical measurement can define the horizontal from the facial midline rather than the edge of a photograph. That is also the approach used here.[1]

1. 1

   Find eye corners

   Select the inner and outer landmarks for each eye.

2. 2

   Fit a facial axis

   Use central landmarks to derive the face midline.

3. 3

   Create face-horizontal

   Use the perpendicular to that midline instead of image horizontal.

4. 4

   Report both sides

   Calculate the two eyes and combine them without pretending they must match.

Sagittal head tilt can alter the apparent angularity of the eye region in photographs, which is one reason standardized camera position matters.[2]

• Camera above or below eye level
• Yaw that hides one side of the face
• Eyelid expression and squinting
• Hair, lashes or shadows over an eye corner
• Filters that reshape or lift the eye area

Drawing a line between the eye corners is easy; choosing zero degrees is the hard part. The top edge of a photograph is only useful when the head is perfectly level. A face-relative method estimates the vertical midline and uses its perpendicular as horizontal. This reduces the effect of a slightly rolled camera or head, although it cannot correct every three-dimensional pose difference.

The test calculates the two eyes separately before producing a summary. Natural sides can differ, and collapsing them too early would hide useful information. Large disagreement often signals head yaw, an obscured eye corner, expression or an unstable detection. Retaking the photo is more responsible than treating every left-right difference as anatomy.

• Positive: outer corner above inner corner.
• Neutral: corner line close to face-horizontal.
• Negative: outer corner below inner corner.
• Asymmetric: left and right estimates differ visibly.
• Unreliable: corners or facial axis are not clear.

Canthal tilt describes one line. The visible eye area also depends on upper- and lower-eyelid contours, how much sclera is visible, brow position, orbital depth, eye-opening height and expression. Two people can share a similar corner angle while their eye regions look quite different. This is why translating tilt directly into labels such as “hunter eyes” discards most of the relevant visual information.

Cosmetic discussions also mix medial canthal position, lateral canthal position and eyelid slant. Those are related but not identical concepts. A browser tool cannot diagnose lid laxity, orbital conditions or surgical indications. It can only estimate visible corner geometry from a suitable photograph.

• Brow height changes the frame around the eye.
• Squinting changes the eye opening.
• Lower-lid position affects scleral show.
• Depth and lighting affect shadow.
• Tilt remains one two-point measurement.

Place the camera directly ahead at eye height and look toward the lens without raising the chin. Keep both eyes open naturally and avoid a smile or deliberate squint. Soft front light makes the actual corners easier to locate than harsh side light. Frames, lashes, hair and heavy edits can cover or reshape the landmarks.

If you are comparing results, reproduce the distance and camera as well as the pose. A wide-angle camera close to the face changes perspective across the eye region. Use several technically similar photographs and look for a stable range instead of treating one decimal value as permanent anatomy.

Canthal tilt concerns the line between inner and outer eye corners. It is not the same as eye slant inferred from the eyelid curve, orbital cant involving the bony orbits, or a diagnosis of canthal dystopia. Online posts may use these expressions interchangeably, but clinical sources define landmarks and purposes more carefully.

Keeping the terms separate prevents a cosmetic photo estimate from sounding like a medical finding. If the question involves vision, eyelid closure, irritation, trauma, a new change or surgical planning, skip the online angle and seek an appropriate eye-care or medical professional.