the angle where the upper and lower eyelids meet

The angle where the upper and lower eyelids meet is called the canthus.
There are two such angles per eye: the medial canthus (inner corner near the nose) and the lateral canthus (outer corner).

Anatomy Basics

These angles form the corners of the eye's palpebral fissure, the exposed opening between eyelids. The lateral canthus sits about 2 mm higher than the medial one in most people, creating a subtle upward tilt that enhances eye shape and function.

In Caucasians, the medial canthus is roughly 2 mm lower; in Asians, it's around 3 mm lower when viewed horizontally.

This positioning supports tear drainage at the medial side and protects the eye laterally.

Quick Facts

• Medial Canthus : Near the nose, often houses the lacrimal caruncle; lies about 15 mm from the nose's edge.

• Lateral Canthus : 5-7 mm from the orbital rim, touches the eyeball, forms a sharper angle.

• Normal palpebral fissure: 28-30 mm wide, 9-10 mm tall in primary gaze.

Feature| Medial Canthus| Lateral Canthus
---|---|---
Position| Inner eye, near nose| Outer eye
Height Relative to Other| ~2 mm lower (Caucasian)| ~2 mm higher
Distance from Orbit| Varies| 5-7 mm

Why It Matters

The canthi stabilize eyelids via canthal tendons, preventing sagging or ectropion (outward turning). Surgeons reference these angles in blepharoplasty to maintain natural tilt and avoid a "sad eye" look.

Age shifts the upper lid's peak laterally, altering canthal appearance over time.

Clinical Insights

Deformities like telecanthus (widened medial distance) or epicanthus (skin fold) affect these angles, often tied to ethnicity or conditions like Down syndrome.

Cosmetic trends on forums highlight "cat eye" procedures tightening the lateral canthus for an almond shape—popular in 2025 K-beauty discussions.

TL;DR: Canthus (medial inner, lateral outer) defines eye corners; vital for aesthetics and function.

Information gathered from public forums or data available on the internet and portrayed here.