Understanding Eye Surgery: Choosing the Right Procedure Based on Type and How It Works

The most important thing when considering eye surgery is not "which surgery should I get" but rather "why this surgery is right for my eyes." This article is based on 25 years of clinical experience and thousands of surgical cases from Dr. Kim Jae-ryong of Kim Jae-ryong Plastic Surgery. After reading this article, you will be able to understand what structural changes in skin and tissue each surgery—such as double eyelid surgery, under-eye fat removal, and epicanthoplasty—creates, and determine which surgical principle will work most naturally with your eye condition.

Eye surgery fails when approached with a one-dimensional concept of simply "making eyes bigger." Each surgical method works differently on the eyelid skin, fatty tissue, eye-opening muscles, and under-eye structures that make up the eye. The overall principles were summarized in Part 1's comprehensive guide. This article explains why each surgery works the way it does and which eye structures are most effectively treated by each method, focusing on skin structure.

Double eyelid surgery is known as "a procedure that creates a line," but its actual operating principle is the process of redefining the adhesion structure between eyelid skin and internal tissue. The eyelid consists of a skin layer, underlying muscle and fat layers, and the deepest conjunctival membrane. To understand how a double eyelid crease forms, you must first understand the adhesion mechanism between these layers.

People with naturally occurring double eyelid creases have them form when the eyelid-lifting muscle contracts as the eye opens, pulling the skin upward. During this process, the skin adheres to internal tissue at a specific height, creating the crease line. Conversely, eyes without double eyelids either have adhesion forming sporadically in the upper skin or no adhesion at all, resulting in skin covering the eye in a straight line when open.

The Operating Principle of Double Eyelid Surgery: During surgery, the surgeon intentionally makes an incision or creates small holes in the upper skin to re-adhere the internal tissue (mainly the eyelid-lifting muscle aponeurosis) to the skin at a predetermined height. Once this new adhesion point is created, the skin gets pulled at that point each time the eye opens, repeatedly forming the double eyelid crease. Over time, this crease becomes fixed on the eyelid. In other words, a double eyelid is not "a line appearing" but rather "a process where adhesion at a specific height becomes fixed through repeated stimulation."

Key Point: Double Eyelid Surgery is Effective Because it Directly Relates to Skin Thickness. The thinner the skin, the more distinct the line appears even with small adhesion, while thicker skin requires larger adhesion. Therefore, even when creating a double eyelid at the same height, the surgical method (incision vs. non-incision) and adhesion strength must be adjusted differently depending on skin thickness.

Under-eye fat removal is not simply "removing puffy fat" but rather a surgery that uses negative space created by structural changes in fatty tissue beneath the skin. The under-eye area has multiple layers of fat compartments beneath the skin. With age or weight gain, this fat descends due to gravity, and simultaneously as skin elasticity decreases, the under-eye becomes puffy and tired-looking.

The Physical Operating Principle of Under-Eye Fat Removal: During surgery, the surgeon accesses the area through the inner lower eyelid (conjunctival side) and selectively removes fat accumulated below the eye. When the fat is removed, an empty space is created, and this space creates "negative space," producing a visual effect of the under-eye becoming more hollow. When this negative space forms, a clear shadow-like boundary appears below the eye, transforming a tired-looking impression into a bright, lively one.

Key Difference: The Reason Under-Eye Fat Removal Doesn't Produce the Same Results for Everyone is Individual Variation in Skin Elasticity and Fat Distribution Pattern. When skin elasticity is excellent, the skin naturally retracts into a hollow form after fat removal, creating a natural negative space. Conversely, when skin elasticity is poor, even after fat removal the skin remains sagging, potentially looking even more hollow or wrinkled. Therefore, accurately diagnosing current skin elasticity and fat distribution before under-eye fat removal determines the surgical outcome.

Epicanthoplasty is commonly known as "a procedure to make eyes bigger," but its precise operating principle is the process of redefining the Mongolian fold and skin structure at the inner eye corner (inner canthus) to increase the actual exposed area of the eye. Many people think eye "size" is judged only by eyelid height, but actually the horizontal length of the eye (the distance from inner canthus to outer canthus) visible from the front is also an important factor.

At the inner eye corner, there is typically a skin fold called the "Mongolian fold," which is characteristic of East Asian eyes. This fold refers to overlapping skin above the inner canthus, and the larger this fold, the more the inner corner appears covered. The Operating Principle of Epicanthoplasty is to incise and remove this overlapping skin and reposition the skin in the inner canthus area, thereby exposing more of the eye's inner corner. As a result, the eye appears "larger," not because eyelid height changed but because the horizontal length increased.

Key Point: The Reason Epicanthoplasty Effects Vary Individually is Because Both the Size of the Mongolian Fold and the Elasticity of the Inner Eye Corner Skin Differ. When the Mongolian fold is large and skin elasticity is excellent, the eye appears significantly larger after epicanthoplasty. When the Mongolian fold is already small or skin elasticity is poor, the visible change may not be as dramatic. Additionally, since epicanthoplasty permanently repositions the skin structure at the eye corner, the final form stabilizes over 3-6 months through repeated scar tissue formation after surgery.

Weak eye-opening strength is medically called "ptosis" or "drooping eyelid," and it is not merely a cosmetic issue but rather a physical structural problem indicating impaired function of the eyelid-lifting muscle. There are two main muscles that lift the eyelid: Müller's muscle and the eyelid-lifting muscle aponeurosis. When one or both of these muscles become weakened, the eyelid doesn't naturally lift, making the eye appear smaller and sometimes even affecting vision itself.

The Operating Principle of Restoring Eye-Opening Strength: To correct this problem, a process is needed to modify or strengthen the weakened eyelid-lifting muscle or its aponeurosis to restore original function. Specifically, the surgeon approaches through the conjunctival side or skin side and reattaches the weakened muscle to a higher position (upper eyelid) than its current location, so the muscle works more powerfully when opening the eye. This allows the eyelid to open higher than before, making the eye appear larger simultaneously and improving a sleepy appearance.

Key Point: The Result of Eye-Opening Strength Correction Surgery Depends on the "Existing Function" of the Eyelid-Lifting Muscle. If the muscle hasn't been completely damaged, function can be sufficiently recovered, but if the muscle is already considerably weakened or damaged, realistic improvement goals must be set accordingly. Additionally, after this surgery the eyelid will tend to droop less, so in the first several days the eye may not close completely or feel awkward—this is a normal part of the recovery process.

When classifying eye surgery, one important criterion is the depth of tissue affected by the surgery. Surgery affecting only the skin surface and surgery affecting deep muscles have completely different recovery speeds, degrees of swelling, and final stabilization times.

Non-incision Double Eyelid Surgery mainly proceeds through microscopic holes in the skin, so the depth of affected tissue is shallow. Therefore, swelling subsides quickly and recovery is relatively fast (1-2 weeks). By contrast, incision Double Eyelid Surgery involves incising the skin and exposing internal fat layers and fascia for manipulation, so deeper tissue layers are damaged and longer recovery is needed (2-4 weeks). Under-Eye Fat Removal and Ptosis Correction require access to even deeper tissue (muscle and nerve layers), so swelling may persist longer (3-6 weeks).

Core Principle: The Deeper the Tissue Damage, the More Complex and Longer the Healing Process. This is because the blood supply needed for skin regeneration, nerve repair, and the magnitude of inflammatory response all correlate with depth. Therefore, understanding the simple but important cause-and-effect relationship that "greater surgical effect = deeper tissue invasion = longer recovery" explains why some surgeries have faster recovery while others are slower.

The most important question is not "which surgery is absolutely the best" but rather "which surgical principle will work most naturally with my eye structure?" To determine this, the following three factors must be evaluated together.

First is skin thickness and elasticity condition. If skin is thin, even small changes are visually noticeable, so more delicate surgery is appropriate. If skin is thick, deeper adhesion or more substantial structural changes are needed. Second is what the current main concern about the eye is. If it's that there's no double eyelid making the eye look tired, double eyelid surgery is more suitable. If the issue is puffiness below the eye making it look tired, under-eye fat removal is more appropriate. If the eye looks tired and sleepy, epicanthoplasty or ptosis correction is more suitable. Third is whether the eye-opening muscle is functioning properly. If ptosis is present, improving other areas may not make the eye look natural, so muscle function must first be checked and corrected if necessary.

Key Point: Kim Jae-ryong Plastic Surgery in Seo-gu, Daejeon considers the process of accurately diagnosing these individual structural differences, explaining the surgical principles suited to each person's eyes, and planning accordingly to be most important. Through 25 years of clinical experience and thousands of cases, we have confirmed that even the same "double eyelid surgery" might be better performed non-incision for one person's skin thickness or incision for another's. What matters is not the surgery name but how naturally the physical and biological operating principles of the surgery apply to your eye structure.

Q1. Should I undergo both double eyelid surgery and under-eye fat removal together?

A: Since the operating principles of the two surgeries are different, you can undergo both together or separately. Double eyelid surgery creates an adhesion structure of eyelid skin, while under-eye fat removal reduces the volume of the fat layer below the eye. If you have concerns about both areas, proceeding with both is efficient. However, recovery time may be longer, so you should consider that daily activities may be limited for a period after surgery.

Q2. Could my eye shape look unnatural if I undergo epicanthoplasty?

A: Since epicanthoplasty removes the Mongolian fold and repositions inner eye corner skin, if performed excessively it can look unnatural. The key is planning an appropriate degree of surgery by considering the current Mongolian fold size and your facial proportions. If skin elasticity is good, a larger degree of correction looks natural, but if skin elasticity is poor, maintaining a smaller degree of correction is more natural.

Q3. How long does swelling last after eye surgery?

A: Swelling duration depends on surgery depth and individual constitution. Non-incision double eyelid surgery typically lasts 1-2 weeks, incision surgery 2-4 weeks, and under-eye fat removal 3-6 weeks. However, this varies individually, so while initial swelling (especially the first few days) subsides quickly, complete stabilization (total resolution of minor swelling) may take longer. Post-surgery management such as cold compress application, adequate rest, and sleeping with your head elevated significantly affects swelling recovery speed.

| Surgical Method | Operating Principle | Recovery Speed | Skin Condition Suitability | Points to Consider |
|-----------|---------|---------|---------------|---------------|
| Non-Incision Double Eyelid Surgery | Creates skin-muscle layer adhesion through microscopic holes | Fast (1-2 weeks) | Good skin elasticity, thin skin thickness | Repeated stimulation necessary for long-term duration |
| Incision Double Eyelid Surgery | Deep layer access after skin incision, forms strong adhesion | Moderate (2-4 weeks) | Poor skin elasticity, thick skin thickness | Scar management, skin elasticity recovery important |
| Under-Eye Fat Removal | Creates negative space by removing medial lower eyelid fat | Moderate to Slow (3-6 weeks) | Excellent skin elasticity, high fat volume | Risk of excessive hollowness if over-removed |
| Epicanthoplasty | Removes Mongolian fold, expands inner eye corner skin | Slow (4-8 weeks) | Distinct Mongolian fold, thin skin thickness | Degree adjustment important, avoid over-correction |
| Ptosis Correction | Restores or reattaches eyelid-lifting muscle function | Slow (4-8 weeks) | Weakened muscle function | Check bilateral symmetry, caution against over-correction |

The most common mistake when choosing eye surgery is deciding based on "this surgery is supposedly good" or "a famous celebrity got this surgery." However, understanding each surgery's operating principle allows you to determine for yourself why that surgery might not be suitable for your eyes.

When you understand the principle of double eyelid surgery creating adhesion structure between skin and muscle layer, under-eye fat removal utilizing negative space, epicanthoplasty expanding inner eye corner skin, and ptosis correction restoring muscle function, you can clearly understand why each surgery has different recovery speeds depending on tissue depth, and why the same surgery produces different results depending on individual skin condition.

Kim Jae-ryong Plastic Surgery in Seo-gu, Daejeon, with 25 years of eye surgery experience, prioritizes consultation and diagnosis centered on these principles above all. By comprehensively evaluating individual factors including skin thickness, fat distribution, muscle function, age, and lifestyle habits, we propose the surgical method and combination that will work most naturally for that eye. Eye surgery is not a matter of selection but rather a matter of design, and the foundation of that design originates from accurate understanding of the operating principles of each surgery.

For questions or additional consultation, please contact 042-477-0011.

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