Generations and Criteria of Vision Correction Surgery

If you're considering or interested in vision correction surgery, you may have heard terms like "3rd generation," "4th generation," or "5th generation" in reference to the evolution of these procedures.

Many people are curious about how these generational distinctions are made and the criteria behind them. This article will focus on LASIK, LASEK, and SMILE procedures to help you understand the generational distinctions in vision correction surgery. We'll also explore which factors might help guide your choice in selecting a vision correction surgery.

Advancements from LASEK to LASIK to SMILE

The history of vision correction surgery has evolved from LASEK to LASIK, and now to SMILE. This progression reflects advancements in techniques that handle the corneal epithelium. We’ll take a look at how these techniques have developed over time to improve treatment of the corneal epithelium as the field has progressed from LASEK to LASIK and SMILE.

Research Comparing 3rd Generation SMILE and 2nd Generation LASIK

To begin, LASEK (Laser-Assisted Sub-Epithelial Keratomileusis) is considered the 1st generation of vision correction surgery. This method corrects refractive errors by removing the corneal epithelium. While LASEK played an essential role as an early vision correction technique, it posed challenges due to discomfort from epithelial removal and a longer recovery period.

The 2nd generation, LASIK (Laser-Assisted In Situ Keratomileusis), later emerged as an improved method. LASIK involves creating a corneal flap, lifting it, and then using a laser on the corneal stroma to achieve correction. This approach allows for faster recovery and reduced pain compared to LASEK.

Study on Corneal Sensitivity Comparison Between SMILE and LASIK

Despite the advantages of LASIK, the process of creating a corneal flap introduced potential complications, highlighting the need for further improvements. In 2008, the advent of SMILE (Small Incision Lenticule Extraction), developed with the VisuMax system by ZEISS, marked the beginning of 3rd generation vision correction procedures.

SMILE involves separating a thin layer within the corneal stroma and extracting a lenticule (a small piece of corneal tissue) through a tiny incision, without impacting the corneal epithelium. This lenticule extraction technique minimizes corneal damage, provides increased stability against external impacts, and allows patients to resume daily activities as soon as the next day due to its quick recovery.

This shift toward more stable vision correction outcomes can largely be attributed to advancements that minimize damage to the corneal epithelium, enabling faster recovery and reduced impact on corneal sensitivity.

Anatomical Structure of the Cornea and Corneal Epithelium

Vision Correction after SMILE: The Emergence of 4th and 5th Generation Procedures?

With the popularization of SMILE, various manufacturers began developing equipment for vision correction procedures that use lenticule extraction, similar to SMILE’s approach. Terms like "4th generation" and "5th generation" vision correction are sometimes used to describe these newer methods. 

But are these procedures truly more advanced than SMILE?

The short answer is that any vision correction surgery using lenticule extraction should be classified as a 3rd generation procedure. As mentioned earlier, the generational distinction ultimately depends on the technique used to treat the corneal epithelium. Thus, terms like "4th generation" and "5th generation" are more marketing phrases than an indication of revolutionary advancements beyond SMILE.

SMILE’s Unique Technology and Patents

One reason SMILE remains distinct among vision correction procedures, even after many years, is the proprietary technology and patents held by ZEISS. The VisuMax device, specifically used for SMILE, has over 240 patents related to its technology.

Here are some key features of the VisuMax technology:

1. Side-Cut Technology

   The side-cut feature shapes the edges of the lenticule precisely, ensuring it separates smoothly without damaging other parts of the eye. This technology allows for safe lenticule extraction through a tiny incision and is unique to ZEISS equipment.

2. Laser Scanning Precision

   The VisuMax device’s laser scanning technology is incredibly precise. ZEISS’s scanning capabilities are accurate enough to target objects as small as a coin from the Earth to the Moon. This precision allows the laser to focus only on the necessary areas, minimizing eye tissue damage and creating an ideal lenticule shape, enhancing both safety and surgical outcomes.

These patented technologies have supported SMILE's effectiveness and safety for over 15 years. VisuMax by ZEISS is also the only SMILE surgery device approved by the U.S. FDA and has been used worldwide in over 8 million cases across 80 countries, including over 1.3 million cases in Korea (100,000 of which were performed at Bright Eye Clinic).

Considerations When Choosing SMILE Surgery

When considering SMILE, it’s important to understand that ZEISS’s SMILE is currently the only true 3rd generation vision correction procedure. When selecting a clinic, make sure to verify that:  

1. The clinic has the VisuMax device by ZEISS, and  

2. The clinic has extensive experience and expertise with SMILE procedures by ZEISS.