Q. This is my first eye surgery—what is the difference between semi-out and in-out?

Hello, this is AB Plastic Surgery.

If you are considering eye surgery for the first time, I think you may have many concerns, such as what kinds of double eyelid lines there are, which line would suit your eyes, and how the surgery is performed. Let’s take a look at double eyelid lines, celebrities who have the kind of lines many people want these days, and what design may be good for your eyes.

When talking about the types of “double eyelid lines,” they are generally classified by shape into four categories: "inline (infold)", "outline (outfold)", "in-out (in-out fold)", and "semi-out." This is a way of distinguishing the shape by the position of the starting point of the double eyelid line on the inner side of the eye, called the “head,” and the endpoint on the outer side of the eye, called the “tail.” Simply put, inline is a small line on the inner side, outline is a larger line on the outer side, and in-out and semi-out are intermediate forms between the two.

If you roughly distinguish them with a diagram, they can be divided as follows.

On the inner side of the eye, there is the red “tear hill,” and there is an inner fold that partially covers it. This is called the “Mongolian fold” or “inner canthal fold.”

“Inline” means the head of the double eyelid begins by merging with this inner canthal fold, and the tail is also positioned close to the eyelid, forming a thin and natural double eyelid line that gives an Eastern impression. In contrast, “outline” starts from a point separated from the inner canthal fold. And because the tail is far from the eyelid, it forms a thick double eyelid line that is almost parallel to the eyelashes, creating a high and glamorous line that gives a Western impression.

The “in-out” and “semi-out” that many people are looking for these days are both intermediate forms between these, with a thin inner part and a thicker outer part.

So what is the difference between the two? Their names differ depending on the position of the head, which is the starting point of the double eyelid line, and the line that follows from it can give a different impression. A picture and explanation alone may not fully convey the feeling, so let’s look at photos of celebrities with beautiful eyes to show these shapes and see what kind of impression they can create.

First, “in-out” is a compound of inline for the head and outline for the tail. It starts from the inner canthal fold like an inline, and the tail extends away from the eyelid like an outline. Representative female celebrities with in-out double eyelid lines include Karina, Irene, and Han So-hee. It is characterized by having both the naturalness of an inline and the refreshing look of an outline.

“Semi-out” can be seen as a slightly smaller and less glamorous outline. The head is separated from the inner canthal fold like an outline, but it starts at a slightly more inward point than a full outline. The tail also extends farther away, as with an outline. Representative female celebrities include Jennie, Jang Won-young, and Go Yoon-jung. It gives a glamorous look like an outline, but can also create a refined look that is not excessive.

You can decide on the line design according to the kind of eyes you want to have. However, whether the desired eye shape will suit you depends on overall harmony, the eye shape, the position of the double eyelid, the distance between the eyebrows, and the position of the eyebrows. In some cases, for a larger and more refreshing eye shape, canthoplasty or epicanthoplasty may be needed, or blepharoptosis correction may be performed along with the double eyelid line to create a clearer and more defined eye shape, which can lead to better results.

Because results can vary from person to person, I think it will be helpful to look into it and then, through consultation with an experienced specialist, find what you were thinking together. Thank you for reading, and I hope this was helpful for those who are considering eye surgery.