Aegyo-sal Filler: Why Can the Small Difference Between 0.2 cc and 0.4 cc Change Your Appearance?

Aegyo-sal Filler: Why Can the Small Difference Between 0.2 cc and 0.4 cc Change Your Appearance?

If you draw a fine line below your eyes with eyeshadow each morning, you may have wondered about adding volume there instead. When you start looking into it, figures such as 0.2 cc and 0.4 cc soon appear. Can such a small difference really be noticeable?

Can a small change in the amount of aegyo-sal filler change the way the eyes look?

It often can. Aegyo-sal is the narrow band immediately below the eyelashes, so a smaller amount can create a more noticeable difference than in broader areas such as the cheeks or forehead. A paper published in an international journal in 2025 described a maximum of around 0.2–0.4 mL per side for needle-based treatment. The paper explained that, even within this range, the amount and injection depth can influence whether the eyes look more lively or the under-eye area looks puffy.

Is aegyo-sal muscle rather than fat?

Yes. Aegyo-sal is the visible fullness of the part of the orbicularis oculi muscle closest to the eyelashes—the muscle used to close and blink the eyes. This area is described as having very little fat above or below the muscle. With little fat to cushion it, even a small additional amount of filler can be visible through the skin, and its shape changes as the muscle moves when you smile.

Why can too much aegyo-sal filler look like under-eye fat?

As the aegyo-sal band becomes thicker, its lower border can become less defined, making the whole under-eye area look more prominent. Depth also affects the shape. The paper mentioned above explained that placement that is too deep may produce overall puffiness, while placement that is too shallow may cause an uneven surface or a bluish appearance known as the Tyndall effect.

Amount or placement	Possible appearance
A small amount	A subtle change that may be slightly noticeable only when smiling
An amount suited to the eye shape	A naturally continuous-looking band below the eyelashes
An excessive amount	A thicker band that may look droopy or resemble under-eye fat
Placement that is too shallow	An uneven surface or bluish appearance
Placement that is too deep	Puffiness across the under-eye area rather than a defined aegyo-sal band

How are the amount and shape of aegyo-sal filler planned?

The paper also advised asking the patient to smile before treatment to identify the natural crease and avoiding adding volume below that line.

At our clinic, the director personally assesses how the aegyo-sal muscle moves during a smile, together with the horizontal length of the eyes, the height of the outer corners and the thickness of the under-eye skin. The product is discussed and selected together based on the skin condition and desired shape, and the amount is limited to what is considered appropriate for the individual.

Are there situations in which aegyo-sal filler is not recommended?

Yes. The paper gave examples including very little development of the aegyo-sal muscle, thick under-eye skin, clearly protruding under-eye fat and significant skin laxity. In these situations, it is helpful to assess the overall under-eye structure before considering adding volume to the aegyo-sal.

A consultation is particularly helpful in the following situations:

• Very little aegyo-sal appears even when you smile.
• You are unsure whether the fullness below your eyes is aegyo-sal or under-eye fat.
• You have had a previous procedure or surgery around the eyes.

The shape of aegyo-sal and the results of filler vary according to the eye structure and skin thickness. An individual clinical assessment can help clarify what may be suitable for you.

The key question with aegyo-sal filler is less about a particular number of cc and more about the amount that suits your eyes.