Medial and lateral canthus: the corners of the eye as a measure
Quick facts
- Definition
- The points where the upper and lower eyelids meet: medial (near the nose) and lateral (near the temple).
- Synonyms
- Endocanthion (medial) and exocanthion (lateral).
- Measurements that use the canthi
- Intercanthal distance, palpebral fissure width and canthal tilt.
- Relevance in facial harmonization
- The basis for assessing the upper third, the tear trough and the gaze.
The canthus is the corner of the eye, the point where the upper eyelid meets the lower one. Each eye has two: the medial canthus (endocanthion), closer to the nose, and the lateral canthus (exocanthion), closer to the temple. Both are anatomical landmarks used in almost every analysis of the periorbital region.
How is each corner held in place?
The corners are held in position by the canthal tendons. The medial canthal tendon anchors the eyelid to the bone near the nose, and the lateral canthal tendon does the same on the side of the orbit. This anchoring explains why the eyelid keeps its shape even with the laxity of aging, and why the lateral canthus is usually a little higher than the medial one in most faces.
Which measurements depend on them?
| Measurement | How it uses the canthi |
|---|---|
| Intercanthal distance | Distance between the two medial canthi |
| Palpebral fissure | Distance between the medial and lateral canthus of the same eye |
| Canthal tilt | Angle of the line joining the medial to the lateral canthus relative to the horizontal |
None of these measurements has a single correct value. They describe the patient's face and help notice asymmetries, plan with more judgment and record the before and after with the same reference.
Why does this matter in facial harmonization?
The tear trough and the tear groove extend between the two canthi, and the look of the gaze depends on the position of the lateral canthus. The professional uses these landmarks to describe the patient's starting point, explain the natural asymmetry between the eyes and align expectations about what harmonization can and cannot change. Bony structures and tendons are not altered by dermal filler.
In Harmy
Harmy does not measure the corners of the eye and does not promise to change canthal tilt. The Tear Trough marking works the area just below the eye, and the projection changes only the marked area, without altering the shape of the eyes. It is an illustrative simulation, not a promise of results.
Frequently asked questions
What are the medial and lateral canthus?
They are the two corners of the eye. The medial one sits next to the nose, and the lateral one next to the temple. They are also called the endocanthion and exocanthion.
What are the canthi used for in facial assessment?
They serve as measurement points: they are used to calculate the distance between the eyes, the width of the palpebral fissure and the tilt of the eye corner.